I have never had to replace a stringer, but I will give you my thoughts anyway. Is a 66 Mustang Fiberglass (if not, never mind)
There are three (or more) ways to accomplish a stringer repair (in order of ease):
1. If the rot is small or localized and the wood is soft, but still there, then use a product like "Git Rot". It is expensive, but the ease of use make it worth the cost. YOu simply drill a series of holes into the rotten stringer and then "inject" the Git Rot into the wood until it will not soak in any more. Buy more Git Rot than you could ever think would be necessary...you will be suprised how readily the wood soaks it in. Once you start, you must complete the operation before the Git Rot (a thin epoxy) kicks off.
2. If the stringer rot is severe, but still localized, there is a pourable stringer replacement product that supposedly behaves similiar to wood (i.e. flexible enough to reduces harsness). To use this product, you must cut away the fiberglass at the top of the stringer and then pour the product in. After it cures, glass in the top of the stringer.
3. If the stringer is mostly rotten, then I suppose replacement is warranted. Cut the fiberglass away at the top of the stringer. Dig out the old stringer and replace with a new stringer. I would be inclined to use kiln dried after treatment treated cypress. Cypress is naturally rot resistant. I suppose you could use pine which is more readily available. The important thing is to make sure the wood is kiln dried after treatment so you do not lock in moisture when you reglass the top of the stringer. You may have to buy a larger or thick piece of lumber and have it milled to the thickness you want. I would then set the new stringer in a bed of thickened epoxy putty to fill voids and ensure a good bond within the original cavity. BTW, this proceedure will require removal and re-installation (or replacement)of the floor.
I am sure others have more ideas and so you will have to decide which method you think will work best for you scenario. Just remember the chief purpose of the stringer is to provide support for the thin skin of the hull. The stringers are not really as much a structural element of a fiberglass boat, but more to keep the thin fiberglass skin from oil canning or bowing inward from the force of the displaced water or impact from waves. They definately provide the support for the engine, so really this is the most important function of the stringer.
So, consider this: If the support for the engine is good or can be repaired with method one or two, AND the fiberglass stinger encasement is sound, then maybe do not even worry about replacing the rotten stringer as the fiberglass encasement will do the work of the original wood element.
Now, if the boat is wood (with or without a fiberglas "skin"), forget all I just said and replace the stringers. Just my $.02, mileage may vary.
|