Marine (BS1088) -v- WBP Plywoods

[Mike]

Here goes with another of my posts where I stick my head above the parapet and tell it like I see it, knowing there is likely to be a cluster of incoming missiles thrown to challenge my thinking. Not to worry - I enjoy a healthy debate. :D

The subject, as detailed in the thread title above, is BS1088 marine grade plywood versus WBP exterior grade plywood. I direct my thoughts to this subject every time I get a quotation for supply of the former - BS1088 marine ply - of whatever thickness I need for my next project. It is VERY expensive material and its cost seems always to be on the increase no matter the economic climate prevailing at the time.

The question to be addressed by many backyard boatbuilders, British or otherwise, is whether or not that cost is justified. And the answers must, by their very nature, be subjective rather than objective. There have been many similar debates on this issue on just about every boatbuilding website you care to mention. So, here goes with my own offering on this topic.

Who am I to express an opinion, you might ask. Well, nobody of any fame or particular standing is the truthful answer. Nonetheless, I am a fairly skilled woodworker, son of a very highly skilled and successful carpenter/joiner/cabinetmaker. I have built small boats (on my own) since the age of 16 (thus for some 45 years now) and helped my father build and sail a couple of his bigger boats in the past. More importantly perhaps, I am entitled while an Englishman to express my opinion freely - at least until our present government decides to remove our right to freedom of expression (they are busily removing so many of our rights that it's hard to keep up with 'em these days). Finally, I am a part owner of this website, so I am here free to quite literally 'publish and be damned'.

Allow me to begin by admitting that, like so many others, I have until now taken cowardly refuge behind the apparent safety of buying the expensive stuff, BS1088 marine ply. I have always bought from a well known and reputable supplier to the boatbuilding fraternity. In the present instance, Robbins Timber of Bristol.

Notwithstanding the excellent advice and service I have had from the Marine Division of Robbins, the question of the high cost, the value for money if you will, of their marine plywoods lurks on in my mind constantly. Surely, it is time for me to express myself plainly and bluntly. Summing up the question that haunts me is so very simple, as follows: "Am I unnecessarily wasting money in paying the disproportionately high costs for BS1088 marine ply?"

When one reads similar debates elsewhere, one is immediately struck by some commonly held misconceptions - even among boatbuilders of some fame and of historically high repute. Many such esteemed enthusiasts have won prizes from one boating magazine sponsor or another for their finished boats. I hasten to say that I have not. But then again, I have never entered such competition. Until now, I have always built for myself, not to place my boats on the market for others to enjoy. This may soon change. All the more reason, then, to focus upon this issue for both financial and safety reasons.

Since I have come into contact with several designers of enormous repute, I have, of course, put this question to them - no names, no pack drill. It may come as something of a surprise to many of you that they all admit quite freely to using WBP themselves, in the present and/or in the past. They invariably place a caveat upon their expressed opinions in that they recognize their unique responsibility in offering such advice on the basis of their expertise. After all, no one in their right mind wishes to find themselves on the wrong end of a legal dispute simply because someone has taken such advice too much to heart - or has misunderstood - and built their boat using rubbish materials.

Nonetheless, you can take it from me as gospel that many esteemed boat designers will suggest you can, in fact, use high grade WBP rather than BS1088 marine ply without placing yourselves at undue risk of structural failure - or worse. I applaud these individuals in that they were, with me, both honest and very clear in what they have said. Essentially, their advice has been the same, as follows. Provided you are building a relatively small boat that will not permanently be afloat and shop around very carefully to ensure that the WBP exterior grade plywood you buy is of sufficiently good quality, you are safe to use it in your backyard boatbuilding endeavour. They emphasize you should inspect each sheet very carefully and the finished boat should have a protective coating to ensure it is up to the task and will last a reasonable length of time.

Given that a number of world famous designers are honest enough to admit that some WBP exterior ply is fine for use in boats, it is perhaps a little surprising to read on other boatbuilding websites that quite skilled backyard boatbuilders hold important misconceptions about plywood? Here are a few of those misconceptions:

1. That WBP is 'WPB' and the acronym stands for 'Weather (even Water) Proof Board".

WBP is the correct term and it means 'Weather and Boil Proof'. Note that this refers to the glue used to bond the laminates together and not to the veneers used. Neither marine ply nor WBP is in fact waterproof.

2. That the glue used to bond the (fewer) laminations in WBP is different to that used in marine plywood, WBP being merely water resistant while marine ply is water proof.

Again, neither product is in fact waterproof, though the glue used in bonding the veneers together is said to be so. I am reliably informed that the glue used in both is in fact the same. The number of laminations can also be exactly the same, though it is important to ensure they are each of approximately the same thickness (watch out for those with thin exterior veneers and a single bulky one in the centre).

3. That exterior grade WBP is all much of a muchness and is totally unsuitable for building safe, long-lasting, boats.

There is huge variation between WBPs. Some are complete rubbish, hardly matching up even to the claim they are suitable for exterior use. Others may in fact be without voids, or with very few and insignificant voids, and of good quality, fairly even, veneer layers. Mark One eyeballing is the way to tell 'em from the rubbish. Those that pass the Mk 1 Eyeball test are perfectly okay to use for building small boats or for bigger boats that will not be subjected to the stresses and strains of the sea or ocean environment (e.g. canal barges, narrowboats, etcetera).

4. That painting marine ply renders it water and rot proof while WBP must be coated with fibreglass to make it so.

Not so, of course, as stated above. Both materials need some form of protection in order to resist water ingress and thus rot. Again, I am reliably informed that paints are not entirely waterproof, especially when they are subjected to wear and tear, as on boats. It is difficult to ensure there is no degradation of their properties, thus regular maintenance is essential whether you are using WBP or marine plywood. I think epoxy coating is perhaps the best way of rendering either product water resistant (as well as stronger), though it seems to me that encapsulation (applying an epoxy coat both internally and externally) is fraught with the danger of making the plywood 'core' subject to entrapped moisture and thus to rotting. Possibly best to coat the exterior alone and allow the interior surface to 'breathe'. Note this does not mean you cannot paint the interior surface - see above re paints not being waterproof.
To be continued ....

[Andrew E]

I bought my 1088 from a UK supplier at much lower prices than Robbins.
Nothing wrong with WBP, except, it is difficult to find stuff without voids. This means inspecting carefully, a bit difficult at a distance.The wood and the glue are frequently the same, though often the inner laminates are of lower quality and less rot resistant. I have another boat on the drawing board, for use on the canals here. I will certainly use WBP for that.
Look at www.marineply.com (http://www.marineply.com) and compare prices. I actually paid less than the listed price for 9mm as it was more than 10 shts.
A

[Clip]

I will add a wrinkle. Years ago I had purchased several sheets of Construction Grade 3/4" pressure treated (green in colour, treated with I suspect a cynide based compound) very rough finished plywood at 25% more than normal 3/4" plywood. This wood was used for cottage shutters, boat centerboard, and rudder. It is fantastic, even pieces exposed to elements for 6 years now with no paint or finish, are still sound.

I have always felt there are different materials used in the other markets that will perform the same if not better than "Marine Grade", at a far cheaper cost due to market demands.

[Mike]

Look at www.marineply.com (http://www.marineply.com) and compare prices. I actually paid less than the listed price for 9mm as it was more than 10 shts.

Good grief, Andrew. You really are a veritable font of knowledge. And you put up links to companies near to where I live which makes them all the more enticing. Thanks once again for the heads up. I'll check 'em out, for sure. :approval:


I have always felt there are different materials used in the other markets that will perform the same if not better than "Marine Grade", at a far cheaper cost due to market demands.No wrinkle there, Clip. In fact it is entirely consistent with my own suspicions. However, I don't think it likely that other plywoods will actually perform better than marine grade. At least not the good stuff that's guaranteed for 15 or 25 years. But to come even close to that performance at a fraction of the cost would be quite outstanding and admirably suit the purposes of many a backyard boatbuilder, I'm sure.

I have a distinct aversion to paying anything like £100.00 per sheet and more (up to £356.00 a sheet for 25mm marine ply). A quick calculation gives me a volume of 0.07625 cubic metres per standard sheet of 25mm marine plywood and thus a price of £4669.00 per cubic metre (someone might like to check me on that one!).

Compare that with the price of sawn planks of solid Mahogany (£2295.00 per cubic metre) or Teak (£7245.00 per cubic metre) and you will see why my aversion. I can see no justification for marine plywood being pitched price-wise at double the volumetric price of solid Mahogany planks, even less reason for it costing a third of solid Teak. What say you?

Perhaps I have miscalculated here, but it seems to me on the basis of my estimates that I might just as well go and learn how to carvel plank a boat and build it from solid mahogany planking instead of working with plywood. Let's face it, I could up the value of the finished product by a vast amount were I to do so.

Best wishes

Mike :captain:

[Audrey S]

So what are we saying folks,

That i'm not going to be hounded from here:beatenup:, for daring to ask

"Can i use WBP ply when the work begins on Audrey S"

[Mike]

Don't quite follow what you mean by "hounded from here for daring to ask", Audrey. Nobody has been 'hounded from here' simply for asking a question - thus far anyway. And I don't think I'm the hounding type. I tend to come straight out with what's on my mind (as you see in this case ;)).

It may just be an unfortunate turn of phrase but a comment like that suggests some prior prejudice when joining us here. Would you care to state the name of the "friend" you said had referred you (http://www.backyardboatbuilding.org.uk/forums/showthread.php?p=504#post504)? And if not, why not?

As to what materials you use on Audrey S, you "can" use whatever you like, of course. It's your boat and your rebuild. If you want advice, then why not simply, and politely, ask for it? You will hopefully receive, nay already have received in posts above, some good tips and suggestions from others here. But remember that all advice is mere opinion.

[Andrew E]

Mike,
I think Audrey might be refereing to the rather agressive attitudes found on other other sites, like WBF, where suggesting WBP ply tends to get one castigated by people who anonymously try to impose their 'correct' ideas.
I got a caning there for suggesting the use of carbon fibre in the glue joints of a birdsmouth mast. The more angry ones waded in without actually reading my post fully. Some kind soul refered me to an older thread were people had actully tried the idea and found it good.

It would be interesting to hear if any body has actually had a disaster from using WPB ply. Epoxy sealed to stop rot, it should be good for some time. All the rough boats I have seen were not built with modern methods and glues. I think most equate the use with poor building techniques rather than a considered choice.
A

[Mike]

Thanks, Andrew

You may well be right about Audrey's post above. It is rather inconsistent with his other posts. And I have seen the sort of thing to which you refer on the WBF. There's a lot of good and helpful advice on that site but there seems to be a minority there who think themselves a cut above the rest of us mere mortals. I think they should set up their own site. WBF's loss would be their own gain then, wouldn't it? Ha ha. :D

You know, that episode we had a few months back has left me a little paranoid these days. But as Henry Kissinger once said, "Even a paranoid has some real enemies." Or words to that effect, anyway. I think I may have to eat humble pie where Audrey is concerned. He's moving that boat to his backyard today so let's all wish him well and hope it goes smoothly. I'm very keen to hear what his other half says when he arrives back with the 'firewood'. That was an unkind remark which would be enough for many to put 'em off the vision they have.

I agree with you about the use of WBP plywood, though I am not yet entirely convinced about encapsulation, for the reasons stated in my earlier post. I guess it would be fine provided the ply was very dry beforehand. Even then, a single penetration could change that completely. I am inclined to go the route of coating the exterior side and letting the other breathe to some extent.

Thanks again for soothing my troubled brow. At the moment, I need that sort of helpful advice from time to time. :approval:

Best wishes

[Audrey S]

Don't quite follow what you mean by "hounded from here for daring to ask", Audrey. Nobody has been 'hounded from here' simply for asking a question - thus far anyway. And I don't think I'm the hounding type. I tend to come straight out with what's on my mind (as you see in this case ;)).

It may just be an unfortunate turn of phrase but a comment like that suggests some prior prejudice when joining us here. Would you care to state the name of the "friend" you said had referred you (http://www.backyardboatbuilding.org.uk/forums/showthread.php?p=504#post504)? And if not, why not?

As to what materials you use on Audrey S, you "can" use whatever you like, of course. It's your boat and your rebuild. If you want advice, then why not simply, and politely, ask for it? You will hopefully receive, nay already have received in posts above, some good tips and suggestions from others here. But remember that all advice is mere opinion.

Sorry Mike, my post was meant to be read "tongue in cheek", A fellow member of WSF (Issy) sent me a link to this site,


Mike,
I think Audrey might be refereing to the rather agressive attitudes found on other other sites, like WBF, where suggesting WBP ply tends to get one castigated by people who anonymously try to impose their 'correct' ideas.
I got a caning there for suggesting the use of carbon fibre in the glue joints of a birdsmouth mast. The more angry ones waded in without actually reading my post fully. Some kind soul refered me to an older thread were people had actully tried the idea and found it good.

It would be interesting to hear if any body has actually had a disaster from using WPB ply. Epoxy sealed to stop rot, it should be good for some time. All the rough boats I have seen were not built with modern methods and glues. I think most equate the use with poor building techniques rather than a considered choice.
A

You've hit the nail on the head, i'm a building contractor and regularly use WBP, hence the reason for my thinking it'd be ok to use,

The hull of Audrey is GRP, and is sound, so the board will only be used in the decks, and superstructure, all mounted on hardwood

[Mike]

S'okay Audrey. I apologize to you. In mitigation, I plead a ruffled countenance caused by some earlier problems with a couple of 'difficult members', putting it rather more gently than I might. Not your fault in any way, entirely my own.

Good luck with the trek today. I think I can safely say on behalf of us all that we wish you every success with your vision. And I think Andrew has it well summed up. The message here is that WBP of a good quality is fine by most of us where the smaller boat is concerned. Don't think I'd use it in a bigger, more structurally complex, design though.

Let's face it, modern epoxies have solved most of the problems that used to blight us. Not all problems, of course, which is why I caution against encapsulation. In any case, if you are a wooden boat fan then good, regular, maintenance is a large part of keeping a boat in first class condition.

Best wishes

[Audrey S]

Mate, if I were to be building from scratch, anything below the gunnells would be built from marine ply,

There is a lot of work to be done to Audrey, it seems that most of bulkheads have been removed, making her a bit "flexible" amidships, my intention is to stiffen her up under and around the gunnel area, and add at least one other full height bulkhead,

Audrey

[Mike]

Hi Audrey

Now that's a pity because it makes it far more challenging to keep the hull fair during the rebuild. As a building contractor, I guess you may know a fair bit about keeping a structure fair so I don't think you'll need much help with that.

Has she flexed much during the move to your home? If so, I'd give her a very close inspection and consider beefing up the gel coating a little after you get the hull faired and rigid. GRP is not something I know much about, having avoided it like the plague since my first 'glass' kayak back in the Sixties. It was strong but awful heavy - and extremely tippy (unstable) compared to my skin-on-frame PBKs.

Regards

[Issy]

Having worked in the Timber trade for many years, I was always lead to believe that the only real difference between Marine and WBP was the way the veneers were laid and the amount of laminations. A good quality Birch ply is laid in the same way as marine ply (though just as expensive). The glues I was always told were the same. If you pay a little more and buy the top quality Malaysian WBP you should get a well finished and sanded ply without voids that will be serviceable on non critical parts of a boat, though for hulls and ant other parts that take the full force of the sea and need strength I would still advise Marine.
I have to point out that I was not an expert in the plywood side but have dealt with it on many occasions and as is my want I used to ask questions and my reply has been derived from answers to those question.
It is best to purchase your ply from a reputable timber merchant and not the local DIY shop or DIY superstore, If you ask a DIY shop abut Quality they will probably tell you that they buy a medium quality and if you ask a Superstore what quality they sell you will probably get a blank look! :P:

[Issy]

Don't quite follow what you mean by "hounded from here for daring to ask", Audrey. Nobody has been 'hounded from here' simply for asking a question - thus far anyway. And I don't think I'm the hounding type. I tend to come straight out with what's on my mind (as you see in this case ;)).

It may just be an unfortunate turn of phrase but a comment like that suggests some prior prejudice when joining us here. Would you care to state the name of the "friend" you said had referred you (http://www.backyardboatbuilding.org.uk/forums/showthread.php?p=504#post504)? And if not, why not?

As to what materials you use on Audrey S, you "can" use whatever you like, of course. It's your boat and your rebuild. If you want advice, then why not simply, and politely, ask for it? You will hopefully receive, nay already have received in posts above, some good tips and suggestions from others here. But remember that all advice is mere opinion.
Actually Mike, I was the friend who gave Audrey the link, I was trolling the web for info to help Audrey and found the site, thought he might be interested and sent him the link. Very glad I did now.

[Mike]

As I understand it, Issy, the real difference between the two is not in the water- and boil-proof glue they use to bond the stuff (I agree it is the same glue) but in the timber used and the way it is laid up. FWIW, I have been advised to avoid birch ply (can't remember why just now). The marine ply I've used in the UK has been from Robbins Timber of Bristol. The hardwood used, even in their lower grade marine ply (called 'Elite'), is lovely to work with and I have not found even one void in my sheets. That is great stuff in my book.

I would love to use their Super-Elite and Super-Elite Plus but they are way beyond my budget at well over £100 a sheet. It's roughly double the price of Elite and I cannot see twice the strength or durability. No doubt it is stronger and more durable - but it's a matter of affordability.

Frankly, I'm with Audrey here in that, on a larger boat like Saving Grace, anything below the gunwales would have to be marine plywood. I differ with him in just one respect: I would use marine ply on all decking too - and I plan to lay teak over that, not bought but machined myself from some beautiful stuff I scored in my wood purchase. I would want it a tad thicker than is commonly sold at an affordable price (well, I have it so why not use it?). However, for interior fitting out where structural strength is not an issue, I would not hesitate to use WBP.

On smaller boats, like dinghies, kayaks, and such, I would be perfectly happy to use WBP. I would still coat it with epoxy on the outside before painting and would also glass it on the bottom up to the waterline. That said, it is not sensible to try to glass a clinker ply design because you end up having trouble at the plank overlaps and can thus ruin the entire appearance of your erstwhile gorgeous clinker hull. On the inside, I would use paint so that the ply can 'breathe' and remain dry.

For those interested, I have discussed this issue of glassing clinker-built with Paul Fisher WRT Saving Grace. We agreed that it would be fine to use the hard chine technique for planking below the static waterline and clinker above. That makes it much easier to glass and will not affect the appearance when in the water.

Best wishes

[Issy]

I only mentioned birch ply to try to explain the laminations, think you will find that birch discolours and is more susceptable to rot in marine applications, Sorry if I mislead by mentioning it.

[Mike]

Yeah. I think that's what I was told about it, Issy. So, not very useful in any marine applications, I guess.

You did not mislead me at all, so no apologies needed. In fact, I'm glad you could tell me what I had forgotten - the reason we should not use birch ply. Thank you. :approval:

[Andrew E]

Birch ply used to be the standard in aircraft aplications. Rot not being a big consideration as non marine. Nice stuff for structural use tho.
A

[pjl83]

hi guys, sorry to jump in on an ongoing thread but thought it was the best place to ask this as it's on topic. I've read that if you are going to use WBP then check before that it is of good quality. What should I look for to determine this. What difference would you tell between a quality WBP and an inferior one if the 2 were stood together?

I rang around the suppliers on the island today and found that WBP was around £14 per sheet and marine ply was around £24. does this sound about right? I was offered an even lesser quality WBP by one guy but I dismissed this straight away, and when I told him it was for a boat he realised why :jaw:

[Mike]

Hi Paul

The devil (read 'difference') is in the detail. First, let me jump in and say that, for the kind of boat you are contemplating as your first build, WBP would do just fine. However, there is WBP and WBP, just as there is marine ply and marine ply. Some WBP ply is rather good stuff, almost comparable with BS1088 marine ply (well, comparable with cheaper marine ply).

What you are looking for is voids in the ply laminations and overlaps in same. To find voids, look at the edges. If you see large gaps (say more than about a half inch) in the laminations, don't buy it. It will let you down. Overlaps show up as raised areas on the faces of the ply. If you can't see 'em, you will certainly feel 'em if you run your hand (gently) over the faces. You'll feel the 'bumps'. It's caused by the inside laminations being overlapped somewhere and it's a bitch to get rid of those bumps.

Ask what wood species is used in the marine ply too. Gaboon (Okoume) is good - looks a bit like mahogany, though lighter. The really expensive stuff is made from mahogany (throughout) and is darker. Cheaper marine ply is available, usually of fir or larch veneers (n.b. softwoods). I would not be tempted. Go for a good grade of WBP.

Essentially, the difference is all about quality of wood, the glues used being much the same, and the care taken in laying up the laminations. Like I said, there is wide variation in both WBP and BS1088 marine ply.

My advice, for what it is worth, would be to never buy your ply on the Internet, sight unseen. Go along to the suppliers and eyeball the stuff. You will soon spot the differences when you know what you are looking for. Avoid buying sheets with voids, overlaps, large knots or plugged holes on the faces.

Finally, remember the old adage: you basically will get what you pay for. Having said that, there are some less than scrupulous suppliers out there who will tell you whatever they think you want to hear. Don't let them think you don't know what you're doing. Ask the right questions and they'll know you at least know a bit and are then more likely to be frank with you.

Once you've found a reliable source of good plywood, keep him in business by going back time and again. Make sure you check what he's delivering to you before signing for it. And thank that good source when appropriate so that he will remember you and try to keep you as a happy customer.

Have fun. Oh, and jumping in on an ongoing thread is exactly what you are encouraged to do here. The more the merrier!

[Arthor]

Hello all,

new here but this is a topic that rages everywhere. The initial point that many designers seem happy for WBP to be used is well made and is perhaps the bottom line?? I have read quite a bit on this and I take it the ways that the two differ are as follows :- The veneers used, the number of laminations and the glues used. I also take it the only ways that one can be superior to the other is in strength and water resistance. Surely the water resistance is a problem for both anyway and that if you encapsulate them totally then moisture is always going to be 'buried' as it is the wood that will give it off rather than the glues. I am sure that Renn Tolman and others recommend full encapsulation with epoxy.
The other issue of strength is surely easiest to overcome by either doubling up on thickness in certain areas (3/4" bottom???) or installing extra (or thicker) stringers/bulkheads.
Doesn't a foam (or balsa) cored panel and an encapsulated ply panel share the same concept?
It is often said that below the waterline should be marine ply but it is ok to use WBP elsewhere. That must surely be down to strength and I am not sure just how much stronger marine ply is compared to WBP and are we talking impact as far as holing goes? (whack on some extra matting and epoxy) or structural? (beef up the stringers and bulkheads)
Having said al the above, I will probably use marine ply unless the cost is grossly above that of WBP at the time and I feel I am getting ripped off.

regards

arthor

[Mike]

The initial point that many designers seem happy for WBP to be used is well made and is perhaps the bottom line??Hello Arthor and welcome to BBB.

Most designers I speak to have agreed that this controversy rages all over the place, yet are not prepared to commit publicly one way or t'other. However, John Welsford categorically states the following on some of his plans/instructions:
"While a good grade of exterior bonded plywood can be acceptable, the designer recommends marine grade plywood unless the builder is very sure of the integrity and quality of the lesser grade product."

John is not one to beat about the bush. And his knowledge of ply is exceptionally good. The key, I feel, is in his warning as quoted above, viz. you must be sure of the integrity and quality of any WBP you intend to use. It's common sense really. There is good WBP and crap WBP, just as there is good BS1088 marine ply and crap BS1088 marine ply.

We all know (at least I hope we do) that there are ply retailers out there who sell what is supposedly marine plywood with BS1088 stamped on it yet it is very poor quality. And I have bought some excellent WBP from time to time that would leave poor quality marine ply for dead.

So, how does the rank amateur tell the difference and make the right choice? I suggest the answer is to first go to a firm you know you can trust and second spend the most you can afford getting the best plywood you can for your boat. You are looking for ply made of decent quality hardwood veneers. It should have very few (preferably no) knot holes or imperfections in it and, most importantly, should be as free as possible from voids and/or overlaps in the ply veneering.

I have it that the glues used in both types are essentially the same. But, if you are not sure then buy a small piece and subject it to boiling in water, lengthy soaking, and drying out in a moderate oven a few times to see how it fares. Remember that WBP stands for 'weather- and boil-proof' and that is what it should do for you in service. If the veneers separate under this torture then it should NOT be used.

Overall, I have to say that I take the view that you basically get what you pay for. I have used Robbins Elite for a long time. Although it is not by any stretch of the imagination the hardiest plywood in their range, it certainly is the best I can afford. If I had 'loadsamoney', I would certainly buy their 'Super-Elite' or even 'Super-Elite Plus', both of which I understand are approved by Lloyds and one of which is approved for lifeboat construction by the RNLI. But I simply do not have that kind of money. So, I will stick to what I know - unless I can find a supplier who can deliver WBP that ticks all the aforementioned boxes at a considerable saving on the cost of Robbins Elite.

As to 'encapsulation', I take the view that it is entirely unnecessary unless you are merely using the wood as a core. If your boat build uses the wood structurally, the only point to glassing is to better protect its external surfaces from damage. For example, it seems a mighty good idea to glass the bottom of your boat if you will be beaching her on sand or rocky shores.

I really don't like the idea of encapsulation for supposed protection. As Arthor notes, there is moisture in wood no matter how it has been dried. Why trap it inside a glassfibre envelope - unless you are only using it as a core and the fibreglassing is where the strength is to be?

Finally, I make the point again that, contrary to some belief, epoxy is NOT waterproof. It is certainly water resistant but PROOF against water it is not. If anyone doubts this, let them read the Gougeon Brothers' book on boat construction. Indeed, just read what it says on the label of most epoxies. It is not claimed to be waterproof, only water resistant. If you really want waterproofing, that is to say you want your wood protected from any ingress of water AT ALL, then you must look elsewhere.

Just my two penneth. And each to his own, of course. :smokin:

Regards

[George Waite]

Lads
I seem to remember a character building (and sailing around the world) a big old sailing Dory (called Eric the Red?). I think this craft was constructed from exterior or shuttering ply.

[Mike]

According to legend, George, the character concerned was one Donald Fiddler, son of an English clergyman, and his book, 'Erik The Red', was a ripping good read.

For those interested in learning more, here's a link to Duckworks Magazine and an article on the book and Mr Fiddler's voyage (http://www.duckworksmagazine.com/04/s/columns/al/07/index.cfm). I have not yet been able to locate a copy of said book but it would certainly make for good reading.

One word of caution, however: Erik the Red only sailed once across the Atlantic and back home again before being installed in the Exeter Maritime Museum. It has now 'disappeared' following the museum's closure. I respectfully submit that such relatively brief, though decidedly arduous, use is insufficient evidence of the longevity of the plywood used. We may never know just how the spartan and low cost building materials Mr Fiddler used have in fact withstood the test of time.

Best wishes

[Arthor]

evening all

As far as encapsulation goes there is a further consideration. If a boat is being built using ply and epoxy, then the ply needs glassing inner and outer as it is only the three in combination that is giveing the strength. ie if you get a strip of 3/8 ply it will bend a lot easier glassed on one side than if it is glassed on both. It is the epoxy bond of the glass to the ply that gives it the strength apparently.
By the way, does backyard boat have to mean wooden boat?? I am considering core cell foam when I do mine. Only because one of the designs I am looing at to buy plans for uses that material.


regards

arthor

[Mike]

If a boat is being built using ply and epoxy, then the ply needs glassing inner and outer as it is only the three in combination that is giveing the strength. ie if you get a strip of 3/8 ply it will bend a lot easier glassed on one side than if it is glassed on both. It is the epoxy bond of the glass to the ply that gives it the strength apparently.We are at odds here I think, Arthor. Plywood boats are not necessarily relying upon the strength that epoxy encapsulation provides. If the designer intends the boat to built in the way you speak of, he will usually specify that the boat is a 'stripper', that is to be built using wood strips, usually western red cedar, and encapsulated in glass & epoxy.

Don't get confused between the terms 'ply/epoxy' and 'encapsulation'. The first refers to epoxy used primarily as an adhesive, the second uses fibreglass (or other, such as carbon-fibre) mat embedded and encapsulated in epoxy. You could use, for example, balsa wood - it's been done - or a core cell foam as the core in the encapsulation method.

And ply/epoxy boats can be built perfectly well without the use of glass and epoxy on either side of the ply. Some are built that way (with epoxy as the glue) and just painted. They work just fine.

By the way, does backyard boat have to mean wooden boat?? I am considering core cell foam when I do mine. Only because one of the designs I am looing at to buy plans for uses that material.No, of course not. 'Backyard Boat' means a boat built in one's backyard or rear garden or shed or garage. I guess it applies to building at home, wherever at home that may be, as opposed to built by a professional at a boatbuilding yard.

If you want to build using a core cell foam, go for it and let us see how you do it. That's the objective here - sharing with others for the benefit of all. :approval:

Best wishes

[Charlie Morgan]

I think Ian Oughtred's concluding paragraph of chapter two in "Clinker Plywood Boatbuilding Manual" provides considerable food for thought.
Charlie

[Mike]

I think Ian Oughtred's concluding paragraph of chapter two in "Clinker Plywood Boatbuilding Manual" provides considerable food for thought.
CharlieAs one who does not own that particular book, I would very much like to know what Oughtred says in that paragraph that is 'considerable food for thought'.

Any chance of you doing a quick copy for us to read, Charlie? :kfluffy:I have explored the possibilities on the Web and, apart from the fact that Chapter 2 is on 'Tools and Materials' and the concluding paragraph must fall within the section entitled 'Fancy Finishing ... or Not?', its content remains a mystery - unless I am prepared to fork out £23.00 odd for yet another book to add to my library.

I have to be honest and say that I find the vast majority of books written by designers all boil down to much the same thing in general terms and that is, essentially, to use common sense and logic and don't be afraid to get stuck in. Good advice but there is a limit to how much I will spend to keep hearing that said.

Regards

[Charlie Morgan]

"The roughest boat ever built to one of my designs was a flat-bottomed Seahorse Skiff built by my friend James........
The construction work was basic carpentry - to put it politely. James sailed her all round the Thames Estuary for 3 months before he got around to giving the hull a couple of coats of oil; he stuck matches in the odd nail hole to keep water out of her. The boat lived out in the weather for years, including 6 months neglected on a beach in Spain. After 7 or 8 years we ripped most of the remaining veneer off the bottom and sides with a belt sander; slapped some paint on her at last, and she was good for another few seasons.
This demonstrates that a boat roughly built of cheap plywood' not finished properly, and not maintained at all, will still last longer than a fibreglass one."

Regards,
Charlie

[Mike]

Ahah! Thanks for taking the time to post that, Charlie. It is both interesting and, dare I say it, dead right. However, I think it applies less as the boat gets bigger and the investment in it larger. For small boats, I believe that a good quality WBP is more practical, because more economical, than forking out big notes for a good quality marine (BS1088) ply.

It's horses for courses, I suppose. I am about to build a Sherpa and a Tender Behind. I am very tempted to use WBP on one and Robbins Elite on t'other, so as to make some valid comparisons. It will depend on what kind of a deal I can get.

Thanks again for sharing that with us, Charlie. :approval:

Regards

[Mike]

Those deeply interested in this subject might like to take a look at my latest blog (http://www.backyardboatbuilding.org.uk/forums/blog.php?b=41) for some pictorial instruction.

Hope you will find it helpful in this particular area.

Regards

[George Waite]

Mike
The present standard of BS marked marine ply falls well below that of past years. I have just purchased a few more sheets for my Dory through a large carpentry run by a friend, we had to reject 60% of the sheets supplied to get enough for me to use. I usually soak them both sides with an epoxy diluted 50-60% with acetone, with 9mm penetration is almost complete. Some of the shuttering (WBP) ply that I have seen used on sites of late is of very good quality and the chippies reckon on a life of at least 20 odd (concrete) pours for a sheet. It is interesting to note that the release oil used in the polished veneer side of the ply seems to aid preservation.
George

[Mike]

I don't disagree, George. In fact, I am quite convinced that there are many suppliers out there who have their own rubber stamp with BS1088 on it.

Frankly, there seems to me to be a lot of plywood being sold that is definitely not up to the required standard and is not, therefore, BS1088 at all but something considerably lower in quality.

A recent experience I had with what seemed to me to be good WBP has led me to feel I cannot trust anyone other than my long-time supplier, Robbins Timber.

To be fair, there are no doubt other suppliers 'out there' who are selling the real McCoy. But I haven't had cause to complain about a single sheet from Robbins. The last delivery I had from them was 10 sheets of 6mm and one of 9mm Elite and there is not one void or flaw in any of them. They are as near perfect as I've ever seen, past or present.

Since I get a good price from Robbins, I am happy to pay a premium for what I know to be first class material. What others choose to do is, of course, entirely up to them.

My own, now very firm, view is that there are an awful lot of rogues and charlatans in the timber supply industry. And unless you know who they are, it is best to avoid change. I think the expression that applies is: "When you're on a good thing, stick to it!". At least, that is how I see it.

I'm staying with Robbins for as long as they look after me and thus return my loyalty. And I'm very happy to say that, so far, that is precisely what they, as a firm, do. I think they are just the bee's knees and I get both excellent prices and excellent service. What more can one ask than that?

If any one of our members ever wants me to help them out by ordering stuff for them, I am more than happy to do so, provided they can come and pick the stuff up from me at my home. On average, I visit Robbins Timber about once a month. My next visit will be next week when I will pick up a back order for some S/S screws and get some lightweight fibreglass for the bottoms of the two TBs I am building.

I would add that every time I visit Robbins, I feel like I used to when entering a sweet shop as a young child. And a walk through one of their timber storage areas is akin to being in heaven for me. The smell, and the feel, even the perfect appearance, of all that lovely exotic timber is just marvellous. Even better than my erstwhile love for the smell of burnt kerosene on the aprons of some busy airport. I feel sorry for those who only order ply from them, especially from afar. They really don't know what they're missing.

Anyway, I am starting to wax a bit lyrical now so it's time for me to close this reply. Nice to hear from you again, George. We must meet up one day, as discussed. ;)

Kind regards

[George Waite]

Mike
I will be in Bristol next week so you can put the kettle on at some point. Robbins have a reputation built over a lot of years in the trade, they used to supply specialist timbers to the shipyard in Bristol where I trained, in fact I can remember recieving some Lignum from them 50 years ago! That's when we used to make chess sets from black Lignum and white teak as apprentice pieces. Funny that you should mention the smell of Kerosene/JP9, I caught a whiff of it passing Yeovilton on the bike the other day and it brought back some memories in the shape of a remote airbase at Khamis Mushayt (Saudi) in 1979 watching 4 Starlifters stacked outward over the Rub al Khali landing in to the dusk with the (American) station chief playing Floyd at full volume over the PA system whilst Iraqi airforce charlies were taking off at the other end for Baghdad in to the darkening night. The temprature was coming down from 52 deg and the air (and my hair) was thick with the sickly stench of the aforementioned fuel.
Enough of this nostalgia!

[Mike]

Mike
I will be in Bristol next week so you can put the kettle on at some point.Okay, no problem George. But phone first please to ensure I'm in. I am making a few shopping trips next week.

Robbins have a reputation built over a lot of years in the trade, they used to supply specialist timbers to the shipyard in Bristol where I trained, in fact I can remember recieving some Lignum from them 50 years ago! That's when we used to make chess sets from black Lignum and white teak as apprentice pieces.Interesting! Their reputation seems well deserved in my experience. As I said above, I find them very helpful and prepared to sharpen their pencil when it comes to prices. And I get on very well with Andy Vowles who, in my opinion, is a darned nice fella as well as a font of specialist knowledge.

Funny that you should mention the smell of Kerosene/JP9, I caught a whiff of it passing Yeovilton on the bike the other day and it brought back some memories in the shape of a remote airbase at Khamis Mushayt (Saudi) in 1979 watching 4 Starlifters stacked outward over the Rub al Khali landing in to the dusk with the (American) station chief playing Floyd at full volume over the PA system whilst Iraqi airforce charlies were taking off at the other end for Baghdad in to the darkening night. The temprature was coming down from 52 deg and the air (and my hair) was thick with the sickly stench of the aforementioned fuel.
Enough of this nostalgia!Some would agree with you that it is a 'sickly stench'. But I did not find it quite that way. There was a time - many moons ago now - when it was a favourite smell, slightly superior to the smell of newly laid tarmac. I guess we all get our kicks in different ways, George. I must admit that the burnt kerosene smell is no longer on my list of favourites. It tends to bring back memories like yours, some of which I would rather not remember, to be honest.

The aviation game never quite matched up to my boyhood fantasies and fell far short of what I thought it really ought to be. Perhaps I have just become a Grumpy Old Man. I don't really know. But it was not difficult for me to leave it all behind and call it a day. My life now is infinitely better for it too. ;)

I had the pleasure of seeing The Red Arrows on display a couple of weeks back and, where it once excited me beyond description, it was all a bit ho-hum for me now. May have something to do with a couple of former Red Arrow jocks I flew with during my career. 'Nuf said on that score, I think.

Boats are my great pleasure in life now and I find they inspire in me feelings very similar to those I nursed during my youth for flying.

Kind regards

[George Waite]

Mike
Can you pm me your phone number as I have lost it.

[Mike]

:banana_guitar:It'll only take a minute.:banana_guitar:

[bemm52]

i'll throw in my 2 bobs worth ..............after first using riddgy didge marine ply at exorbedent prices I tried imported hardwood marine plys at slightly less cost but pigs to work with......................Where from here financial controler must be soothed at al costs (keep build costs down and slip under radar).....................so next step construction ply in my neck of the woods 1/3 price of marine ply..............downside in 3-7mm only 3 ply available over that thickness more veneers..........waterproof glue..good............bad its all radiata pine C-D grade.............one good side one ordinary but cheap at the end of the day
I'm building my Houdini out of construction grade.......... the fact that it soaks up epoxy resin to me is a bit comforting and I'm sure extra resin used will still come in cheaper than marine ply

Cheers Paul

[jwboatdesigns]

Mike,
I think Audrey might be referring to the rather agressive attitudes found on other other sites, like WBF, where suggesting WBP ply tends to get one castigated by people who anonymously try to impose their 'correct' ideas.
I got a caning there for suggesting the use of carbon fibre in the glue joints of a birdsmouth mast. The more angry ones waded in without actually reading my post fully. Some kind soul refered me to an older thread were people had actully tried the idea and found it good.

It would be interesting to hear if any body has actually had a disaster from using WPB ply. Epoxy sealed to stop rot, it should be good for some time. All the rough boats I have seen were not built with modern methods and glues. I think most equate the use with poor building techniques rather than a considered choice.
AThere are two "tribes" on WoodenBoat forum, lots of sub groups within those as well but the two main "tribes" are,
The devotees of solid wood carvel or clinker planked as a boat would have been built in the early 1900s, and those who espouse heretical stuff like epoxy glue and plywood, carbon fibre and stainless steel.

No matter which discipline you prefer, when you post you'll get a negative reaction from the "other tribe".

Dont worry about it, there are a few who are reasonable and if you are looking for information you may have to sieve through some replies of indifferent quality, but more often than not someone will have what you need.

John Welsford

[jwboatdesigns]

More than 25 years ago I built Hobo, one of the first of my experimental designs. This boat has water ballast tanks and all sorts of other unventilated rot traps, and as I was poorer than usual at the time I used CCA ( copper chrome and arsenate, common in treatment of wood for ground contact) treated CD Radiata construction plywood.
Coincidentally a gent rang me yesterday to ask about the boat, he was looking to buy it and it is still in good shape. ( no epoxy coating, just oil based enamel house paint!)

I've been using Wayang brand Marine Bonded Exterior Red Meranti plywood for maybe 30 years, never ever had a failure, never had anything to complain about, and some of the boats have had a very hard life.

John Welsford



i'll throw in my 2 bobs worth ..............after first using riddgy didge marine ply at exorbedent prices I tried imported hardwood marine plys at slightly less cost but pigs to work with......................Where from here financial controler must be soothed at al costs (keep build costs down and slip under radar).....................so next step construction ply in my neck of the woods 1/3 price of marine ply..............downside in 3-7mm only 3 ply available over that thickness more veneers..........waterproof glue..good............bad its all radiata pine C-D grade.............one good side one ordinary but cheap at the end of the day
I'm building my Houdini out of construction grade.......... the fact that it soaks up epoxy resin to me is a bit comforting and I'm sure extra resin used will still come in cheaper than marine ply

Cheers Paul

[Mike]

Hiya Paul (bemm52)

It sounds like the problems and issues of which we speak here are universal. Like I said, I reckon high quality exterior WBP can be superior to so-called BS1088 marine from the yards of the rogues and charlatans. And I wouldn't hesitate to build a small boat using good exterior ply.

Your Houdini - a great little ship in my never humble opinion - will no doubt serve you extremely well and I look forward to seeing some photos of her when you have time.

I really think the lesson to be learned here is to examine closely the ply you intend to use - exterior WBP or that stamped as BS1088 - and to do so with an open mind but a wary and critical eye. It is the inside plies that matter most. You don't want fancy outside plies hiding voids and complete rubbish inside the panels. Avoid such inferior material like the plague as it will definitely let you down at some stage.


I've been using Wayang brand Marine Bonded Exterior Red Meranti plywood for maybe 30 years, never ever had a failure, never had anything to complain about, and some of the boats have had a very hard life.There ya go. Straight from the proverbial horse's mouth. And John worked in the supply side of the timber industry for very many years so knows what he's talking about, particularly when it comes to plywood.

I take it, John, that the CCA preservative stuff you mention is the same or similar to the green impregnated stuff I see when I visit my local DIY hardware store - on posts used for fencing panels for example? If so, I've plenty of confidence in its ability to keep out the bugs and rot for a very long time as I've used that myself, not for boats but for fencing, of course. I was warned to watch out where kids and animals are concerned as it's poisonous. Presumably it's an arsenic element in the 'A' bit? :)

[George Waite]

Mike
Yes its Arsenic alright and if it was not so toxic it would make a great antifouling!

[Ricsudukai]

Copper-Chromium-Arsenic - reasonably toxic on a number of levels - here is a good link :- http://www.csiro.au/resources/CCATreatedTimber.html
We had a pretty nasty bushfire here a few years back, burnt out 220,000 acres in a few hours, killed 9 and destroy generations of sheep breeding and lovely old homes. When working in the fire and in the weeks after it many of us absorbed a lot of dust and all sorts of chemicals - re-fencing was a point, as we were scuffing through the dust left when a CCA post is burnt. Many of us became very crook, I as well after three months, and found myself in bed for about three or four months after, and not real good until this last year or so.

Mind you, the oyster farmers use CCA post extensively in my old fishing grounds - something I have vigorously lobbied against to absolutely no effect. The treatment works by leaching into the surrounding area, which is soil normally and prevents fungal and insect attack - any bug that starts to bore into the treated wood above ground finds the toxin load very disagreeable, but what happens in salt water?? I guess the treatment washes out pretty fast, as a post that might last three decades in a paddock rots and gets attacked by borers after only two or three years in the sea - the big strainer posts driven into the sand at each end of the lines last maybe ten years max. You get why I am a little tetchy about the idea perhaps....

I just treat all synthetic timbers as highly toxic, ply, MDF, doesn't matter. When using some very exotic timbers from time to time I can tell you - there are some very nasty timbers out there that can drop you on the spot if you are careless. As has been said many times by people that actually know what they are talking about - check your ply carefully for voids and inner ply quality, and come to your own conclusions, the marine ply bit now days is pretty meaningless unless you are buying from the handful of trusted sources and have resources such as this forum here to gain some idea of who to trust. I have been supplied locally with Malaysian 'marine ply' which actually isn't too bad - but the face veneers are .8mm thick - don't use a sharp pencil 'cos you wont sand it out..... I have used it a fair bit fitting out commercial boat interiors and for floors and some furniture structure - if it works on a tuna clipper in the southern ocean, it'll be fine in a small boat I figure. And it is all that is available here unless I want to buy great stacks of the stuff and have it freighted here. I will use this stuff for re decking(and re cabining, and re transoming, and re quite a bit more actually....) on the mighty Hartley 18 that is turning into mushroom compost as I type.

Might be easier to build Saturday Night Special and just get back on the water - I like quick and dirty......

[jwboatdesigns]

Interesting, grapes are among the most sensitive crops grown anywhere, and in this country they, after much research use CCA treated pine poles for their supports. The testing showed no leaching that could be detected, same with the domestic landscaping and foundation materials that have been very closely monitored by the green activists but even the most agressively anti among them have not come up with anything of note.

I've had a lot to do with the sawmill industry over the years, treatment systems included, so have some knowlege of the process and results. If done properly the treatment agents chemically bond to the wood fibres, and cannot wash or leach out. If though its overdosed the unbonded agents may be free to roam. At higher concentrations such as those used in ground contact materials this is a critical judgement, and treatment plants are supposed to have covered areas where the excess chemicals can be run off back into recovery tanks so they dont contaminate any soils or groundwater.

Even burnt its not supposed to come out of the ash, although I'd imagine that in the very dry the airborn ash would not be good to breathe, and I'd take great care with sanding dust or anything kicked up by the planer.

But all that said, dont barbeque your sausages over offcuts of CCA treated wood.

John Welsford

[Ricsudukai]

Hi John,

I can't draw any inference about CCA treated timber other than advice from forestry workers from years ago regarding burning of the same and avoiding any contact with the smoke or residue. Further to that is the very precise advice given to us when re-fencing after the bushfires by the authorities regarding the risk to stock and humans when in contact with burnt CCA timber and it's ash in particular. This must be removed entirely or buried before any stock were to be allowed back into the area - unfortunately many of us did not take enough personal care and paid the price. To describe the conditions in summer heat with zero ground cover and any breeze at all as hellish is a gross understatement. :death: Breathing mask filters blocked solid within minutes and within the hour everyone was the same colour of dirty ash. The dust drifts in our caravan which is what we had left after the fires were 5 - 10 centimetres deep every day for months. I agonised for weeks after the Victorian fires, but accepted advice that it was not safe from a health perspective to place myself back in the conditions that I have barely recovered from - so have not gone to build or fence this time. I make do with donation and fund-raising in a minor way this time. And sending my sister over for a few weeks. Nice brother eh.

I am not qualified to have more than a layman's feeble authority in the chemistry or technicalities of CCA and won't attempt to claim anything more than second hand and hearsay knowledge on the subject. My reference to the leaching effect is as per the published data from CSIRO - and known not to affect crops such as grapes and fruit. Root crops such as carrots etc. within a pretty close distance (100mm - out to 200mm or so) are shown to have elevated arsenic levels - mostly removed by peeling.

My reference to CCA treated timbers being used in a marine environment is that unless it is H6 level treatment it is not marine rated - and that is the issue for me with unsealed CCA in the water.

However I see no issue with WBP, or CCA timber used in a boat if sealed correctly. It may be heavier and it might not be very strong compared to true Marine ply, but if sized correctly and avoiding dry knots and defects so the strength is o.k. will work fine. It's only absolute high performance rockets built to perform within a rule set that must have ultralight construction - for casual use it is more important to build affordably and get on the water. A safe and solid economical boat will get used a lot - and that's the main point. :goodnight:

[Mike]

Hi Ric

I don't disagree with what you've said above but I would add that the vast majority of WBP plywood sheets I see these days here in the UK are potentially a problem if used to build a boat. This includes many that purport to be BS1088 compliant but definitely are no such thing.

Perhaps the best advice any one can give, no matter where in the world one is giving it, is to be careful. For me, the main issues are strength and durability. I willingly pay the premium for marine ply that carries the Lloyd's approval and is guaranteed for 15 years. And thus far have not had a single sheet that disappoints in any way.

However, if I intended to bang together a quickie for some fun on the water, with no concern with regard to seaworthiness or durability, I would definitely go for cheaper plywood.

As to CCA treated timbers, I can't see any reason to use them for boatbuilding but if they come cheap enough then why not? I guess it depends on what boat you are building and for what particular purpose.

[Ricsudukai]

Hi Mike - I have used some CCA stuff in commercial boat fitouts, but that is as frame members for seating and wall panelling - and was based purely on cost, or the lack thereof. I would not use it for building a boat for me, or structurally in any boat unless H6 rated. Then it is normally heavy and of not very high strength anyway.

I must admit my probable choice of a cheap Malaysian "Marine ply" is purely economical in the extreme, it will do the job when repairing the Hartley 18 festering away in the darkness of my yard, but I will look seriously at bulk buying the good gear should finances take a turn for the better.

No such thing as bad timber, just what it is suited to.

So by definition there is some that isn't even good for firewood......

[Bruce Peckett]

Here's my two pennorth worth on plywoods ...

You do get what you pay for and if I was building a major project such as my dream cruiser (if I ever settle on exactly what the dream is!) I wouldn't compromise. It'd be top quality BS1088 marine ply from a reputable supplier and no mistake.

However, on a knock about or a tender or a chuck it together job, I'd buy WBP but there's good and bad and downright bloody awful and it's very hard to spot the differ until it starts warping and delaminating

We put new sides onto the wooden cabin of our 37' narrowboat some years back. We did one side using 9mm WBP from B&Q and the other using apparently identical plywood from Wickes. The B&Q side still looked good 10 years later but the Wickes side was splitting and delaminating within weeks (both sides were identially painted etc. and the boat was not exposed to some exceptional elemental conditions on one side only)

The Wickes ply also would not take a decent paint finish no matter how hard I tried. Despite half a dozen coats of high build undercoat and several coats of topcoat the finish still cracked and crazed within weeks. Within a year we had to rip that side off the boat once again and replace the lot

There is one good test and that is to cut a 1" square off the corner of a sheet of ply and boil it. If it's good WBP it shouldn't delaminate for several hours (I forget how many) 'cos the B in WBP stands for boil! Bad stuff will fail in short order and should be rejected for anything other than concrete shuttering which is all it's fit for. Of course, we didn't do this. Ho hum.

Another useful test is to leave a large piece of ply out on the grass overnight when there's a dew and a bit of damp in the air. Crap ply will be warped to hell and gone or even delaminating in no time whereas anything worth using will still be good.

There is one other potential serious problem with WBP for boat hulls and that is voids. The major difference between WBP and BS1088 marine ply is the requirement for the later to be free from voids. Voids in a hull? Not good! There's not a lot you can do about it and any that become evident can, I suppose, be filled with epoxy but it's the hidden beggars that'll get you. H2O will find it's way in sooner or later and rot the wood from the inside out.

It comes down to a judgement of the life expectancy and relative value of the hull under construction versus the extra expense of marine ply over the ordinary stuff. Only the builder can make that judgement IMO

You pays yer money takes yer choice!

ATB
Bru

[bemm52]

Hello all,


Having said al the above, I will probably use marine ply unless the cost is grossly above that of WBP at the time and I feel I am getting ripped off.

regards

arthor

for a while there I thought you were on my side...............I think this marine ply thing was probably a big issue years ago when epoxies were not in general usage..............my el-cheapo exteria ply sucks epoxy more than marine ply I used previously............to me this is a good thing.........If I wanted to paint and preserve a hull without epoxy encapsulation I would probably choose marine ply ............is it such an issue now??????????

[Mike]

for a while there I thought you were on my side...............I think this marine ply thing was probably a big issue years ago when epoxies were not in general usage..............my el-cheapo exteria ply sucks epoxy more than marine ply I used previously............to me this is a good thing.........If I wanted to paint and preserve a hull without epoxy encapsulation I would probably choose marine ply ............is it such an issue now??????????Well, it is perhaps an even greater issue now, bemm52, insofar as there are many suppliers out there who stamp their ply with the BS1088 mark when, in fact, the ply does not comply with the basic standard. That was not common in earlier times and would hopefully have been dropped upon by Trading Standards from a great height.

We all know that things have changed, rarely for the better, and there is a lot of so-called 'marine ply' that is no such thing. Further, there is WBP and WBP. Are we expected to run a test of an off-cut by soaking and boiling every piece we buy? I think there is only one way to go if you have any regard for your own and your loved ones' safety and that is to pay the extra money needed to ensure you have Lloyd's approved BS1088. After all, the single sheet difference in price, while seemingly awesome at first glance, must be worth its weight in gold in terms of confidence in the structural integrity of your own build.

At least, that is the way I see things. It costs more at the sheet purchase stage but, in terms of the overall cost of the finished boat, it doesn't make a lot of difference.

I rather enjoy the peace of mind I get from using Robbins Elite rather than WBP bought from the local hardware store, no matter how nice the local chap may be in letting me sort through a pile of rubbish in order to find what I think is not so much rubbish.

Just my own view, of course, and we are all free to do as we choose. However, there is no point in complaining, for example, about the 'unfairness' of the Brussels-imposed RCD if one has little regard for the quality and integrity of the components one uses to build a boat that may end up in the unsuspecting hands of another. No doubt this was an influencing factor in the 'five year rule' that allows us to build a boat for 'own use' and then retain it in use for at least five years before being legally entitled to sell it to another.

Best wishes

[Rational Root]

Boy do I pick em for my first post..... :waving:

What I'd like to add is that not all BS1088 is the same either. I've picked up a sheet which was stamped BS1088 and sold as Marine ply.

For 6mm ply, it had a two outside plies that were marginally thicker than paint, and a softer central core about 4 mm thick. In total it was < 5mm thick.

Thus you may argue over using Marine Ply or not, but you still need to take a long hard looks at the hard stuff underneath the ink.

That which seems too good to be true, is. :nono:

Sadly, I bought a sheet of this before I knew the little that I know now. Fortunately I learned enough that this particular abomination got painted black and used for a chalk board for my kids.

[Mike]

Boy do I pick em for my first post..... :waving:

What I'd like to add is that not all BS1088 is the same either. I've picked up a sheet which was stamped BS1088 and sold as Marine ply.

For 6mm ply, it had a two outside plies that were marginally thicker than paint, and a softer central core about 4 mm thick. In total it was < 5mm thick. ...

That which seems too good to be true, is. :nono:Welcome Rational Root. Yep, it's a hot potato, this subject.

If you read all the posts in this thread, you will see, I think, that the warning you give is already in there - more than once as I recall.

I like your latter comment above, which is really what it's all about. If you want quality then it is invariably necessary to dig a little deeper in your pocket - the one where you keep your ill gotten gains, that is.

Another way of putting it is that old adage that you simply get what you pays for.

Regards

[Ray Frechette Jr]

Late to the conversation and thread is rather long.

I didn't have time to read all posts, but thought I would share my views as a pro builder anyway.

Once a boat is built it is far easier to upgrade items sucha s rigging and sails and such stuff than to upgrade the base structure of the boat.

I would opt to economize on other aspects of the boat before choosing a lesser grade of ply.

As a pro builder, the savings form lesser ply is miniscule over entire cost of boat. My labor is more expensive than materials of boat.

I simply will not build with anything less than 1088 ply from a recognized supplier such as Shelmman or Brunzeel or Joubert. And I always get it from a distributor with a reputation at risk who is not going to sell knockoffs.

I wouldn't touch Chinese ply irregardless of what label is put on it. Not that they can't make a good panel mind you but they seem to have their fair share of charlatans cheating people and little internal policing that I simply have no confidence in them at all.


Now, when building for myself as opposed to hired work, I have used lesser panels before such as MDO Medium density overlay which is a fir panel with paper resin bonded to the faces.

I had read on forums as to what a nice product it was and how much it saves.

I no longer ever consider such and will now only use 1088 on personal builds as well.

It is not a question of lopngevity or usefullness, but the savings were not all that great and it doesn't work nearly as nice.

If I need to save money I buy Hydroteck Merranti as it is substantially cheap[er than Okoume althoug it is about 20% heavier, doesn't bend nearly as nicely as Okoume, and it has copious splinters that burn in skin contact.

The MDO I bought was roughly same price as Merranti, didn't bend nearly as well and was heavier and had voids.

I much prefer building with 1088 Okoume.

I won't even give a thought to using US Fir based plys such as AC exterior etc.

Now all fo above is based on prices I get for 1088 with a major marine lumber yard serving all of the pro shosp up and down the coast here in Maine and from what I have seen my prices are better than what others in other locations have to work with.

And it is al together possible that in EU you have better quality panels generaly available to the building trades which can clearly alter the equation, but that is how I see it here.

At best on a 17 foot boat cheap ply might save 2-500 dollars US. Thats not much of a savings when looking at a boat that will end up costing around $17,000.00 is it? If a client insists on the cheap ply I advise them that I don't think I am the right builder for them and they may wish to check with other builders instead.