Sea Plane tenders

Damboline is a breatheable bilge paint made by international,

it is a bit expenceive though

also, it does not matter how thin the ply is, it will only bend in 1 direction. (try it with a piece of paper)

Edited by clive

dgray wrote: I think the 3mm ply will bend in 2 directions OK. I'll check again. I was keen on ply as I could remove it at a later date without ruining the planking underneath ( as I would if I used  finreglass matting). What I don't understand ( and I haven't explained well) is:- If a wooden boat is bilge painted and painted/antifouled on the outside then water cannot get in  - or out.  The same with sheathing I'd have thought unless it gets trapped between the ply and the planking, you'd have no problems.   That said, you'd have the same problem on a triple diaginal hull as the outside layer is immersed in water and the timber can only dry out through the bilges. In that case it looks as if  epoxying the existing planks and then building up the matting/epoxy is best as the epoxy is chemically bonded to the outer timber and leaves no gaps for the water to get in. Obviously replanking the hull is best but that gets rid of most of the original timber and makes it into a renovation rather than a restoration. Thanks everyone for the advice. I'll look at cascover and perhaps a dehumidifier....

Renovate or restore, call it what you like, keeping original timber is nice, preserving for the long term is important.

One key problem with epoxy on wood boats is that the planks move more than the epoxy and the epoxy opens up where the movement is, ie all along the caulk lines.

Epoxy coatings are good for hot and cold moulded hulls and for plywood hulls, but not for double diag.

If you put epoxy on a weak hull with de-zinc'd screws it wont work long term.  The boat has already survived a lot longer than any ply will last.

Best thing to do is re-instate the condition of what you have.

IMVHO.

Thanks for all the constructive comments.

I really haven't explained this very well. The hull isn't weak, frames have been repaired/replaced where necessary. I'm also making another 100' of (roved) bilge stringers that were removed from both boats (before I bought them), so as to restore the hull's lateral integrity.

Forgetting for a moment about breathable paints (thanks I didn't know about them!),  the thing is,

If the ply is be fixed with (probably) thousands of screws (doubling the number originally used to fix the planking), how does it really differ from an original boat ( except for the point from burgundyben about movement in a D/D hull) inso far as they both have identical (waterproof) painted bilges and painted/antifouled hulls?

My question really  is,

Imagine 2 identical boats, one epoxy sheathed, the other not.

How will the unsheathed boat 'breathe' better than a sheathed boat when they both are sitting in water? Both outer hulls are in the water and both with the exact same painted bilges.

It's what really confuses me.  I know that it confuses others so  I hope that this epoxy/don't epoxy subject is intertesting to others (especially ST owners).

Thanks everyone for your continued indulgance.




Edited by dgray

clive wrote: HSL 102 has been epoxied as has '81 and 1502, '102 having lasted 11 years now, what is her condition? it does not show on the sale advert...

And very important to note that all three were completely refastened before the epoxy went on.

 

 

I plan to refasten the hull as the ply would have a new screw between each of the originals.

There is a waterproofing product used by builders called "Thompsons".
Works well on wood as it penentrates deep and "Prevents water penetration whilst allowing trapped moisture to escape".

If a boat epoxied with ply will be as strong as Fibreglass matting (assuming the ply is very well fixed and F/G taped at seams ) then it seems to have 2 major advantages....

1). It is removable without really damaging the original timbers underneath.

2). You've refastened the hull with screws.


It would be really interesting to hear from the BMPT regarding 1502 and how the sheathing worked out....  Richard?

Cheers