Lately I have been purging my computer of many bookmarks and saved items that relate to other boats and stuff. I ran across and article that describes sealing deck penetrations in fiberglass boats with cored decks. It seems that there are innumerable instances where the wood core material used in the decks of most of the fiberglass boats that have been built, usually either end grain balsa or marine or at least exterior plywood, becomes wet and then gets mushy and will eventually rot. This phenomenon has been traced to poorly or even unbedded deck fittings and penetrations. There are many products and procedures that are in practice in the workshops of many production boats, not all of them work as desired or proposed. Here is a link to an article that I have decided makes alot of sense, and I plan to put into practice on my Navigator build. Check this, ( Butyl tape deck sealing ) out, I found this when researching repairs to the Catalina C22 that I was almost going to get deeply involved with. It really made so much sense and knowing that several of the very very upper class of builders do it this way, why shouldn't I? Can't think of a single reason!!
With our little boats being almost all plywood, which presents so much end grain that will allow the wicking of even the smallest amount of moisture, let alone a splash or wave of water, to wick up into the ply and eventually wind up possibly anywhere within the entire boat promoting the beginning of rot everywhere. Well it may not be that bad but the beginning of rot anywhere in an all wood boat could become disastrous and it isn't something to be overlooked. We need to be extremely careful how we treat any hull, deck or bottom penetrations. I know it will add a great deal of time to construction, but hey, I'm retired, got nowhere to go or be except right here in the workshop with my boat. Well, soon to be a boat anyway.
So the plan is that wherever I put a hole through the ply, such as for rudder gudgeons, or cleats, or turning blocks, oar locks, bowsprit bolts, cockpit drains, whatever, the hole will be put through oversized, filled with thickened epoxy then redrilled correct size, thereby sealing the edges of the hole in the ply from water penetration and then properly bedded with butyl tape. I vow to not use "the Devils Goo" (3M 5200/ 4200/ 4000 or any other) on my boat ! If it needs to be attached that strongly then a mix of epoxy and silica and or wood flour will have to suffice. Also making sure that there is a properly sized backing block for support of items that will be under a load, such as cleats, blocks and such.
I am planning to start purchasing lumber to begin the building jig when paid at the beginning of the month, which at first will be used as a work table for things such as frames, bulkheads, spars, stringers, rudders and centerboards. Then after the majority of "small parts", as if a 14 ft long mast is a small part (!!!), the legs of the jig will be shortened to a comfortable building height. As a work bench I plan the legs to be 36" tall and cut them down to about 18 to 20" to build the boat itself. I believe that will be a height that will allow reaching where I need to above the jig and also reach under to fasten anything that needs it from below. The reaching under is an important consideration as I don't get "under" very many things with any ease at all these days. Of course this is all just guess work at this point as I have not started building anything yet.
I guess I will find out soon enough.
Geoff
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