Stringer fab and transom replacement

[Smokin'Mo]

I am working on a 21' Campion Discovery, 200hp Merc Offshore O/B. Floors are cut out, stringers are removed, stringer support fibreglass stripped from hull. (a cup type wire on a high speed angle grinder works great for this). My transom also needs replacing but does not have an inner fibreglass liner instead there is an additional layer of 2" plywood laminated to the 1" piece laminated to the hull and transom skin. Middle portion is rotted only on the 1". Can this be fixed without removing all of the transom plywood?

I have heard that rigid foam in sheet form can be used to model/sculpt a template from which to fabricate a wooden stringer. Has anyone heard of anything else used to fabricate stringers from other than wood?

 

[rockyrude]

Re: Stringer fab and transom replacement

How comfortable do you feel having that 200 in the boat with you? If you think the rot is limited to a thin area against the transom fiberglass then it's worse than it looks. Rot is very misleading. For a 21' offshore I'd rebuilt at least as strong as it was. Foam cores and such are risky for the pounding that hull takes.

 

[Smokin'Mo]

Re: Stringer fab and transom replacement

So wood is the way to go for the stringers?.

I plan to remove all of the wood in the transom and replace with new.

 

[rockyrude]

Re: Stringer fab and transom replacement

I would definitely replace with wood. My 19' airslot had only 3/4" stringers so I went back with 5 ply plywood and glassed them in. If you look around, you'll see a lot of discussion about using pressure treated, I personally used it.

 

[SgtMaj]

Re: Stringer fab and transom replacement

Welcome to the forum, and to the stringer/transom repair ow my back hurts club!

 

[Old Salt Oz]

Re: Stringer and transom replacement

Re: Stringer and transom replacement

We avoid the use of timber as much as possible in the marine environment as it has proven to be unsuitable, it will not tolerate moisture, rots, warps, splits is high maintenance all round.

Having said that, if we do use timber it is first dried in a kiln, coated with a minimum of 5 coats of epoxy resin after shaping and more on the end grain or edges of ply.

Small stringers are made with foam and extra glass used to give the requires strength, again using only epoxy resins.

All limber (drainage) holes are drilled oversize, filled with epoxy and Micro-Fibres then re drilled to the required size and electrical conduit glued in using epoxy to provide protection and a solid seal.

Any holes drilled into the transom are treated as above to ensure no moisture enters the ply.

Also note:
All repairs are carried out using only epoxy resin as this will bond to poly and epoxy resins. Standard poly resins will not bond well to an epoxy. Most epoxy resins will require coating to protect them from UV light, this is not required for standard poly resins.

I hope this helps.

Andavagoodnewyear......

 

[BillP]

Re: Stringer fab and transom replacement

Use pressure treated wood if you want the best of all worlds...high strength to weight, way lower cost compared to structural foam...and takes less glassing than structural foam, easy to work with, can use with polyester resin and it's rot free.

bp