Plywood hull and chine repair advice

[fergie_mac66]

chuck some salt in any hard access bits when finished. Salt helps to stop rot

[oldsaltoz]

Originally Posted by fergie_mac66

chuck some salt in any hard access bits when finished. Salt helps to stop rot

I always thought salt attracted moisture.

[fergie_mac66]

Originally Posted by oldsaltoz

I always thought salt attracted moisture.

timber boat that get fresh water,rainwater or fresh condensates in rot very fast. The salt help to prevent any fungal attacks (dry rot) which can profligate in damp condition .If the timber is well protected from moisture absorption . The salt helps to stop any fungal growths attacking the timber.

Wet rot is a nuisance but If you get dry rot fungus then you can kiss good by to the boat.

Its worth putting timber fill its on the tops of ribs etc to stop drips collecting

and make sure your limber holes in the bilges are free and clear

http://diydata.com/problem/timberrot/timberrot.php

this site gives gives details of types of rot

[Tranona]

Don't forget this is a hard chine Ply boat and should be watertight. Provided you stop rain water from getting in through joints and fastenings (hence the importance of using epoxy on end grain in glued joints), just paint is more than edequate protection. I use Danboline internally up to the waterline and conventional paint above. Externally, if not sheathed a proper paint system is adequate, but some prefer to coat with epoxy first. Remedies and protection suitable for conventional timber construction are largely irrelevant.

[EastCoastChris]

Originally Posted by oldsaltoz

Are you planning to coat the exposed ply and timbers?

Epoxy encapsulation is not necessarily the panaceae it may first appear to be. If I was building a new boat from scratch I certainly would epoxy encapsulate and put glass cloth on the outside. Retropsectively applying epoxy to just the outside of the boat does little to inhibit the internal freshwater that is the cause of most rot. Applying epoxy to the inside and effectively covering the entire internal surface without leaving any bare spots where water could penetrate behind would be next to impossible. One thing worse than water in the plywood is water in the plywood behind epoxy.

She's 30 years old and reached that age through the use of good quality plywood and being painted inside and out. I'm sticking to that successful approach.

Originally Posted by Seanick

A half lap onto the surrounding panel would not have gone amis.

It wasn't a joint in the plywood that failed, it was where freshwater had been held against the old chine log and hull in the middle of a panel.

Originally Posted by fergie_mac66

timber boat that get fresh water,rainwater or fresh condensates in rot very fast.
Its worth putting timber fill its on the tops of ribs etc to stop drips collecting

I've not decided on the final solution yet, but I am planning on doing something to make sure that water doesn't collect somewhere other than in the bilge. I've thought about fillets but if you look in one of the pictures where the hole is cut above, you can see the member that the sink drain gate valve is sitting on. You can see the angle of the hull means that water would have to flow up and over some members.

As for salt, I'm a little puzzled by that one, I understand the idea to tackle the freshwater, but it does attract moisture and what stops it dissolving away into the bilges? I was thinking Intertox or some other sort of penetrating fungicide/preservative treatment before painting would be a good start.

Plywood boats can't be made rot-proof, but on the flipside they are almost infinitely repairable.

Chris

[Seanick]

Re: Half lap, I was refering to the repair!

[EastCoastChris]

Sorry Nick, I realised after I'd posted that I might have misread your post. Apologies

Chris

[fergie_mac66]

well salt is the old remedy. Intertox etc will do it but if wood epoxied then no penetration ( also serious poisons). I think the theory is the roots of dry rot (not called roots can't remember name) are microscopic they tunnel through anything into the into wood can spread right thought out the boat unseen. Little enclosed area small amount of fresh water moisture and dark,fungus can gro quickly.Salt stops fungus spores dead can't grow. the wood is protected from wet rot by epoxy and paint. well vented clean bilges common sense but there's aways that little spot . The moisture evaporates in warm weather but leaves the salt behind .Wet rot easy to cure cut and replace

mind you old remedy could be old wives tale but it makes sense as salt is a preservative

[Seanick]

Originally Posted by EastCoastChris

Sorry Nick, I realised after I'd posted that I might have misread your post. Apologies

Chris

No worries, nice job though. Just paint her up as usual and its probably the only repair you will have to do for years.

Tranona-my boat is 'traditional' and does not leak-ever! :-)