Epoxy Resin over wood

[airborne1]

Hi, I have raised this subject in the Classic Boat forum but would like a wider opinion if possible.
Firstly, let me thank all the posts in the Classic Boat forum which were both interesting and informative. I did read them all and added the comments to other research I have carried out.
Now I would like to throw this subject open to other posters who don't read the Classic Forum.
Having done done research on epoxy resin over wood, mainly the external face of my hull, I have come across an article by "West Systems", who I think is regarded as the definitive authority on epoxy reson and fabric coating, who tells me how to apply it to both "Hard Wood" and "oily wood ie Teak". Therefore it seems that the technique IS applicable to sheathing my wood hull. Also, apparently GRP hulls are made using wood cores and those hulls seem to last many years.
Therefore, my question for the wider community is this.
Can anyone give me a good reason for NOT filling the opened seams of my dry hull with string soaked in resin. Then coating the hull with one layer of "thin" resin, followed by another coat of "thick" resin with embedded cloth. Then 4 layers of resin Coppercoat anti fouling.
As far as I can see, the layers of resin will prevent any water penetrating through to the wood. Therefore the planks will not get wet and ipso factor will not swell and crush the rigid seaming and or cause dimensional distortion. The amount of moisture and water which can get to the wood from the inside should be negligible, especially Iif I never allow standing water in my bilges and give the inside a good coat of paint.
I know that some readers of these forums will say that I am making a big fuss about this subject but I have the subject "in my teeth" and don't seem to be able to get rid of it.
I am running out of time for various reasons and MUST make my choice very soon.
Thanks for any posts that help me make up my mind

 

[fluffc]

[ QUOTE ]
The amount of moisture and water which can get to the wood from the inside should be negligible, especially Iif I never allow standing water in my bilges and give the inside a good coat of paint.

[/ QUOTE ]

So you're going to keep the boat in a warm, dehumidified shed then? Best o' luck...

The sea water that keeps a wooden hull 'sweet' does a jolly good job of preserving it. Fresh water is a killer of wood.

 

[airborne1]

Fluffc, believe me one reason for me chasing this answer is exactly so I can get the boat OUT of a dry but far from warm shed. Its been in there for 6 months awaiting my boatbuilder attention, when I can get his attention away from all the nice pretty gin palaces.

 

[EASLOOP]

I met you on the Classic forum but regarding your question I felt I would like to add a little to my other reply.

If like me you have a wooden front door in your house you may well have noticed that the door begins to jam when the weather is wet. It may be because the door is too finely planed down but never-the-less the door will expand in the wet. Your door is not underwater and perhaps only gets the painted exterior of the door a little damp i.e. not drenched with pouring rain. So the wood, when in a damp environment will expand.

Your boat is on and in the water totally immersed below the water line. The upper sides are sitting just above the water level in water saturated air. So the boat is going to swell no matter how much epoxy you have lathered over it.

You will be at high risk of cracking frames, planks and other structural natural products in your boat as she takes up.

I may be wrong but I beleieve that the Gudgeon Brothers (West System Epoxy) say that the only way to do what you want is to completely encapsulate each piece of timber with epxy then build the boat.

If you go ahead with your plan perhaps you could let the forum know the outcome. It may be that some folk, including me , may have to adjust their understanding. Although I doubt it.

 

[airborne1]

Thanks EASloop, believe me, I have read all the posts on Classic Forum with great interest. As I said, I am not rubbishing any of the posts.
I did find this advert on www.yachtsnet.co.uk/boats/r22206/r22206.htm
The quote that intersets me, and maybe others asking similar questions:

'Bente' was built in Norway in 1939 as a 40 square meter 'Spisgatter' cruiser-racer, of close seamed Norwegian pine on oak frames at 8" centres, copper and bronze fastened. This yacht was almost totally rebuilt in the 1980s, and relaunched in 1986, re-engined, and with the hull epoxy-sheathed, a new alloy rig, and a complete new deck and coachroof in WEST wood-epoxy. Since then she has cruised extensively, crossing the North Sea again twice, and raced successfully in classic racing".

Has anyone any more info on this boat or others that have been sheathed. Perhaps its the technique or type of resin used that makes the difference. I do note what you say about the front door. But in this quote I note the word "Sheathed", taking it to mean only the outside of the hull rather than both sides. And what about the wooden men-0-war which were copper sheathed from keel to well above waterline without the planking being damaged.

 

[EASLOOP]

Good point re: wooden me-o-war. But perhaps they were copper sheathed (no glue) after the hull had had a good dunking.
Perhaps plank width is important as well being more amenable to sheathing if really narrow.
Don't use polyester resin, it is completely unuseable in marine environment structural work.
Good luck

 

[airborne1]

EAsloop, it is interesting as to how they sheathed the old men-o-war ships. Does anyone know ??
As to the resin to be used, I will certainly be contacting the various manufacturers to find the most suitable product. I take the point about polyester. West System do mention a "wood" expoxy resin but I am not an industrial chemist. Perhaps there is a surveyor or chemist reader who can give some input as I am sure that this subject may be of interest to lots of bloaters.

 

[flykeith]

I'm in the position of having a cascover sheathed boat which probably needs refastening. I have already found a few places of rot which were well hidden by the cascover, so I'm quite keen to return to wood and paint. Removing the cascover is also likely to mean complete re-caulking due to the resin in the seams (brittle without the sheathing). So I'm tending to go the opposite way to you, but then again I'm very new to wooden boat ownership!

 

[Niander]

I would ask on this forum also as these guys know all about wooden boats

http://www.woodenboatvb.com/vbulletin/upload/index.php

but what you suggest sounds flawed to me
If you can keep it wet for long enough it may even seal itself naturally as it takes up the water and swells.

 

[Niander]

Nice boat Fluffc!

 

[ccscott49]

The old men of war, were sheathed with copper sheets, copper nailed to the planking with tar in between, the sheets could move with the planking, but they used to rot like hell anyway! The copper was not there for waterproofing, just to stop or reduce fouling. Only ships built to a high standard had copper. Some had a sacrificial layer of pine nailed to the oak planking, to give the borers a place to eat, this was periodically stripped off, with the borers in residence and a new layer put on.

You go ahead and do your epoxy sheathing, you dont seem to want to hear what is said anyway, you just keep quoting this norwegian boat, I can show you wooden boat yards all over the world with disasters caused by sheathing wooden hulls.

But I'm willing to be proved wrong.

By the way, my boat has sheathing to 12" above the waterline, but my hull is splined, making it basically one piece of wood, then it was sheathed from new, with cascamite and nylon scrim (cascover). I have also sheathed other boats with epoxy, double diangonal, but never a carvel normally caulked vessel, I've seen too many disasters.

The wood in fibreglass hulls, (mainly end grain balsa) is only there to hold the two layers of fibreglass apart, forming a double skin for strength and most hulls arent "cored" only the decks.

You arent listening.

Rant over.

 

[Danny Jo]

[ QUOTE ]
Can anyone give me a good reason for NOT filling the opened seams of my dry hull with string soaked in resin. Then coating the hull with one layer of "thin" resin, followed by another coat of "thick" resin with embedded cloth. Then 4 layers of resin Coppercoat anti fouling.

[/ QUOTE ]

That's an awful lot of time and money to spend on a scheme that carries a serious risk of failure due to moisture ingress from inside. Wood expands, epoxy doesn't.

And undoing it again might be a nightmare.

I have a boat built in wood epoxy. The survey suggested a hull water content that was much as it should have been when the boat was built 18 years earlier, and the cedar strip inside looks much as it did when it was first epoxied into place. But someone knocked the pulpit a few years back. It is bolted through an glass-reinforced-epoxy-encapsulated hardwood gunwhale/stringer/thingumebob and the retaining nut broke through the glass-epoxy capsule. It was not resealed, water got into the wood, caused splitting of the capsule over about 300 mm, allowed more water in, with the result that I now have a weak, cracked glass-epoxy shell around a whole lot of wet powdery mush. Next winter will see me crouching in a cramped anchor locker with mask and goggles trying to cut out and rebuild the rotten section.

Building in wood epoxy works if you control temperature and humidity during construction. I would consider epoxying a wooden hull only if you can strip out all the fixtures and furniture, inside and out, including chainplates, stanchion bases, winches etc.

If you don't want wooden boat maintenance problems, sell it and get a GRP one.

 

[airborne1]

Thanks CCScott49 for your info on copper sheat sheathing.
Indeed I am listening VERY, VERY hard to ALL the posts that have been sent. This is one thing I DO NOT want to get wrong. I have a few more people to consult such as my surveyor before I commit.
I just want to get it right and I believe in doing my research thoroughly. There is a good deal of time, money and effort involved so please don't take my quest wrongly.
Thanks once again to all the posters.

 

[gtuson]

I think there may well be aproblem if the the wood is not completely encapsulated in epoxy. We rebuilt a steel hulled motor sailer - and did superstructure in marine -ply. This was fully coated in West system epoxy before being fixed in place -even the bolt holes were epoxied.... But any damage that results in water getting behind the epoxy will, I'm sure cause the ply to expand/distort and god knows what else...Full encapusaltion stabilises the wood as it cant absorb moisture...without it the wood is bound to change character from changes in humidity and temperature and this will compromise the epoxy coating....IMHO....

 

[airborne1]

Thanks to all respondents to my query on both Classic and PBO forums. I think I now have enough info and opinions on this subject to form a qualified and informed way ahead.
I think this subject should be ended now.
Thanks again and if anyone is interested in which route I choose then I will set up a diary on what happens.

 

[Spuddy]

Was mentioned on Classic forum and I too can vaguely recall article in the mag about california outfit going to some lengths to epoxy up old classics that were otherwise write offs. Was a few years ago but might be worth asking back copy dept.
That sort of cladding technique will cost loads in materials and take more time than you might think. Whereas getting a canny craftsman to do it tried and tested way has got to be less for a predictably good result.
I appreciate that you want to be convinced through evidence and maybe want to pursue your research more.

 

[ningcompoop]

wooden boat restoration and repair
is the gougeon bros' guide to boat restoration using west epoxy. It does cover what your asking about. Its only cheap, so why not get a copy?
Of course, what you really need to do is find someone who's actually tried this, and find out what happened! The wooden boat forum mentioned above may be useful there.

 

[Robin2]

I think there is a fundamental difference between a boat with traditional caulked seams where the expansion of the wet timber is an essential part of the sealing process, and a boat which is designed from the outset never to get its wood wet because it is encapsulated in glass cloth and epoxy.

Also, it is essential to have the wood at a suitable (low) moisture content before applying West System epoxy. I doubt if it would be easy to achieve that low moisture content on a boat that had already been in the water - unless it was on the hard for so long that timber shrinkage became a problem.

If it was my boat, I would conclude that it is too late to consider sheathing it, unless you plan a very extensive dry-out and re-build. And with the gaps I have seen in a dry hull the cost of the epoxy to fill them would not be trivial. It might be better to re-plank the hull.

Sorry to sound negative.

 

[airborne1]

Thanks to all your comments. It certainly helped me to reach an INFORMED decision.
Although I have been told of wood boats which had been epoxy clad I could never get a good explanation of the process and any pros & cons for it.
Therefore I have decided to go with the traditional paint methods. Luckily I did manage to sell my Coppercoat to a freind who was considering using it anyway on his GRP hull. I just had to offer to scrape his old anti-fouling off in return for lots of beer.
Thanks again and I think this should conclude this subject. Hope it may be have been of interest to others contemplating the same route.
And for those interested, I did indeed take all the opinions offered and I DID listen.