Originally Posted by
Slab
Some more advice Rojoguio provided to me in PM I thought I should post for all to see. Don't worry, I asked his permission to share.
So "Stringer 101" is, nothing solid is laid against the fiberglass hull skin. All stringers float in any quality boat construction. I placed compressible material within the old channels left by the original build. I did not cut completely out. If something is laminated hard against the hull it creates a point for the skin to be fractured against. If you run the hull up on a stump with the trolling motor while fishing and the stump is pressing on the flexible side of the skin the weight of the hull could crack the fiberglass skin against the hard lamination point. Some stringers have raised spots left while cutting out the stringer to hold the stringer up a 1/4 -3/8in above the hull skin for lamination. I use 1708 S-Glass for all stringer work and making deck panels due to the non-woven nature of the reinforcement. It is sewn together with a lite scrim. Stringers can be done in sections, can be done completely one side then the other. As far as pouring the stringer I would not recommend that, I have written numerous posts in BBC about the engineering of a pourables being used in say transom repair.
Here is another "Boat repair 101" to remember, Polyester has a 300psi adhesion - Epoxy has a 3000psi adhesion. New polyester does not like to stick to old polyester. A mechanical tooth must be applied to the substrate. Also acetone washes are necessary if using polyester resin. I used vinylester resin a lot here but due to low shelf life switched to polyester if doing that type of repair later on. Everything else got epoxy. If for no other reason than the fumes. All my laminating & gelcoat in solid colors came from Advanced Plastics. They have several warehouse distribution points I'm sure somewhere in Central florida has one. Coosa Bluewater 26 is the only material I used for stringers, transoms, and decks. In stringer repair the outer lamination does most of the work, if properly done the form material should be able to be removed. Watching the building of a Phoenix you can see the stringer system is just another fiberglass lamination that is filled with a rigid foam after being installed in the hull. Wood works fine as it is not relied on for providing spine, that is provided by the lamination laid over the wood returning to the hull skin. Wood is heavy, absorbs water (condensation makes water in every hull on earth as the hull warms and cools, you can't stop it), and is susceptible to decomposition. Today the cost of Coosa from Advanced Plastics is higher than ever but cheaper than anywhere else. They delivered here for $75. It was not worth my time to drive to the New Orleans warehouse to pick up.
P.S. I used a 13# Grinder with a wire Cup for cleaning the crud off the hull skin. You do this after all the gunk is out and it is completely dry. It works ridiculous good. I will post a picture in your thread.
Thanks for posting Slab. I hand wrote it out to go in my boat book for future reference. Writing it out may be "Old School", but it helps me understand it better, as well as stick in the brain better. Thanks to you for posting and John for sharing some of his wealth of info.
Proud to have served with and supported the Units I was in: 1st IDF, 9th INF, 558th USAAG (Greece), 7th Transportation Brigade, 6th MEDSOM (Korea), III Corp, 8th IDF, 3rd Armor Div.
1980 Ebbtide Dyna-Trak 160 Evinrude 65 Triumph