Ok, next round of questions.
I'm nearing the point of needing to start building my new stringers. I'm replacing about a 6' length of stringer on each side - the section that was wet. (I wrestled on/off with popping the top off, and doing a whole-hog, guts-out structural restoration, but the transom test holes were good, and I managed to cut forward/aft into solid wood in the stringers, so the risks of the balls-out, top-off restoration seem to outweigh my interest in doing a full-up structural restoration. (A. the time/expense; B. the chance of introducing a bend/warp in the hull that could adversely affect handling/driveability; C. the chance of introducing enough of a distortion that the top might never go back on)
So, the questions:
1. I've got the stringers cut off with a perpendicular edge at the front and back ends, and my plan is to custom fit the new stringer sections in as butt joints with reinforcing plates on both sides of each butt joint. I've seen most/many pictures and descriptions of this type of joint using a reinforcing plate on only one side of the joint. Is there any reason to not put a plate on both sides? (I don't want to waste my time/effort/materials, if its of no added value, and I also don't want to do it if it might cause a problem - too stiff at the joint?? - but, it seems that both sides make the most sense? Also, should my butt cover plates also be made of 3/4" ply, or would 1/2" ply on each side be good enough? (I'm not at any shortage for plywood - just a question of weight/stiffness in these joint areas - if triple-layered (ie, the 3/4" stringer, then 3/4" plate on both sides, we're talking 2.25" of thickness - just want to be sure I'm not overdoing it to ill effect.)
2. In addition to having to do wood-to-wood joining at the butt joint plates (ie, the side of the stringer glued to the side of the plate), I have a 3' section of the stringer that was doubled up in the original structure. (The stringers are 3/4" ply, but are doubled to 1.5" for about 3' in the middle.) This thread started about encapsulation of the floor - this question is about joining/sealing these wood-to-wood joints. For the double-thickness section of the stringers, as well as the cover plates at the butt joints - should this be direct wood-to-wood gluing? Should I coat both layers with an encapsulating layer of epoxy first (ie, let the epoxy soak into the wood), then glue them face-to-face? Should there be a layer of glass between the faces? I plan to glass the heck out of whatever I end up with, once its in place. (ie, in addition to tabbing to the hull, I'll be running glass up over the tops, to be sure all is thoroughly covered) My plan is to use a peanut-butter consistency of epoxy with milled fibers (West 403), to do these face-to-face pieces, as I've read in multiple places (to include the West site), that 403 provides the strongest bond in this type of situation. Does that sound right?
3. To Limber or Not to Limber... As noted previously, every one of the little compartments under the floor (as created by the stringer/bulkhead layout) was sitting full of wet foam, and this seems to be a large part of what led to these sections of floor, stringer and bulkheads being soaked. The 'plan', putting this all back together, is to make it essentially impossible for water to get into these sections, but its water... It will eventually get everywhere, I'm sure. With that in mind, I'm leaning toward putting limber holes in the stringers for each of these little compartments, so that if/when water does get in, it has a way out. (OTOH, that also provides a place for water to get into both the compartment, and possibly even the stringer), though I'm refilling the compartments with cut sections of pink foam board oriented vertically, so it shouldn't soak up water like the old spongy expanding foam did.) I also plan to not mount the seats through the floor, as was originally done, but to mount them to plates glassed to the top of the floor, which should cut down on what was, I'm sure, a major water entry point. SO, the question... To Limber or Not to Limber??
4. Is there a way to adequately glue/glass in a bulkhead to which you only have access to one side? The rear bulkhead in the interior section (there is one further back - right at the bilge area, that is solid, and seems to have been glassed like they meant it, so I won't be replacing it) lies between the currently-gutted passenger area, and the bilge. There is a section of floor here (on which the gas tank is mounted) that sits under the rear top section of the boat, and is in good shape., and that ends at this bulkhead in question. (I'd have to pop the top off to replace at rear-most section of floor). This bulkhead isn't in bad shape - its not perfect, but its far from rotten or spongy. It could be left in place (with a newly-applied layer of glass on the side I can get to, for some refreshing of its water resistance), but if there is a way for me to replace it, and sufficiently glue it into place, I might well go ahead and do that. The thing is, I can only get to it from the front side. This wouldn't be a big problem for cutting it out, but when it comes time to put it back in, the best I could do would be to lay a huge bead of peanut-butter, push the bulkhead into place, and hope that the PB all stays in place long enough to dry. (I would obviously fillet, tab and glass the front face that I could get to.) SO - do I leave this in place, do the best I can for it from the front side, and just don't stress it (again, its structurally solid - not like new wood, but not falling apart, by any means), or do I cut it out, and perform some type of circus trick to be sure its PB'd in from the rear side? (I guess the other option is, I could cut away just enough of a small section of rear floor, such that I could get an arm down in there behind it, do the best one-armed glassing job that I could from the back through this hole, and then patch in the little cut-out section of floor - I just kinda hate to monkey w/ that section of floor, as its in pretty good shape back there, as it currently stands...) The good news is, this section is under the front edge of the cap, so doesn't receive any foot traffic or such.
5. Between this bulkhead (described in question 4) and the next one up (about 3 feet forward - presently removed), is the section of the floor where anyone getting into the boat steps - whether stepping down in from the dock (which often involves a small hop, given that the boat sits pretty low), or from the rear of the boat (coming into the boat from the water - also often involving a small hop, just because lots of kids come into the boat from the water) This section had an extra layer of wood stapled/glued underneath it in the middle section between the stringers. (not up to the stringers, but in the general area between them) It was not glassed at all - just stapled/glued to the bottom of the floor - I presume to account for this being the landing zone when entering the boat. I'm putting 1/2" marine ply back down in its place (I don't believe the original floor was marine ply, but it was 1/2"), which will be encapsulated and glassed on both sides. My question is, should I replicate the extra layer of 1/2" ply in this section (glued/filleted/glassed), or would I be better off adding another bulkhead in this section, so that there was something spanning the width between the bulkheads in this landing zone? I don't want to introduce some type of 'hard' point in the hull that wasn't there, but nor do I want to go through all of this work, just to end up with a small trampoline in the middle of my boat. I suppose an alternative would be to not put in a full bulkhead, but to glass a block to the insides of the stringers on each side, and have something solid (laminated ply? some type of hardwood?) oriented long edge vertical (like a 'T' beam, or 'I' beam), and spanning the gap (glassed to the little blocks on the inside of the stringers, and PB'd to the floor underneath), but not actually touching the hull, if that might be better from a weight/stiffness/hardpoint perspective. Thoughts?
6. Lastly, I plan to use colloidal silica as filler for my fillets, and ordered some fast hardener for doing fillets and vertical surfaces, as I've read that epoxy wants to run (even when thickened) when applied thickly in fillets on on vertical surfaces. Does this sound sensible? (ie, the silical for the fillet thickening, and fast hardener for fillets and vertical faces)
Thanks Again for all of the help - Now that the guts are out and cleaned up (and now that I finally reached a conclusion on what/whether to do about removing the top), there is a faint light that I think I see shimmering at the far end of a small tunnel. (Its entirely possible that its just FG in my eyes, but I'm gonna say its a light at the end of the tunnel...)