Deck encapsulation and tabbing question

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jim_s

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Update and inevitable question! :) I think I'm officially done demolishing, grinding, etc. The interior is all smoothed out, cleaned up, vacuumed out, etc - I'm genuinely ready to start putting pieces and parts together. (Big sigh of relief - I have come to detest grinding and sanding fiberglass, though I fear that dust and bits will continue to exude from the boat for quite some time to come!)

In measuring, planning and preparing to cut new stringers, I've come across a bit of a head-scratcher. I have stubs of good/dry stringer in the front and back of the boat (I kept cutting outward from the middle, until I reached solid, dry wood), and I left the outer sections of the bulkheads (it, outboard of the stringers), because they were pretty well sealed up (wood isn't 100% perfect, but there is as much fiberglass structure there, as there is wood, and they're so small, that I don't really think they're doing much structurally, anyway - big point was, however, I was able to retain a reference for stringer and deck height, where I pulled the stringer sections out). One of these bulkheads is at the front, where I stopped cutting stringer, and one was about in the middle of the section I cut out.

So, I stretched a string from the top edge of the front stringer stub, to the top edge of the rear stringer stub, to establish where the top of the stringer would be, and to start figuring out what kind of cuts/angles/etc I needed to put on the bottom of the stringers, so they'd fit the hull. The string on the port side lines up perfectly with the top edge of the wood on the port side outer bulkhead section (the one in the center of the cut-out stringer section). On the starboard side, however, the string sits about 3/16" below the top edge of the wood of the starboard side outer bulkhead section. The string would represent the top of the stringer and/or bottom of the floor. So, something is a little bit amiss here.

I don't know if the original stringer had a 'hump' in it (I'm replacing a 52" section of stringer on both sides, and this bulkhead is about 1/2 way down that length, so we're talking 3/16" height rise over approx 26" of length - not a huge 'hump'). Or, if there is something about the way that the boat is sitting on the trailer bunks, or something about how I braced the underside of the boat with additional wood (so that it wouldn't flex around when I was working in the boat) that has introduced a 3/16" upward bend into the hull on the starboard side. (This seems the most likely in terms of what *could* be wrong, but least likely in terms of what *is* wrong - the bulkhead bit sits between the chine and the lower/outer edge of the hull, which is a fairly well structured section of the hull - I can't imagine how that area would get pushed up, as its probably the beefiest section of the hull, aside from the keel and the transom...) The hull is sitting flat on the trailer bunks - if anything, the bunks bow down a little bit *away* from the hull near that area where the bulkhead bit is (just old bunks). I put an 8' section of 2x4 under the hull on each side, inboard of the trailer bunks (so, even farther away from the outer bulkhead bits), and used blocks and wedges between the trailer and each 2x4, to hold it snugly up against the hull. The area where the blocks/wedges are, are well behind and well forward of the bulkhead bit area, so I don't really think those are putting any particular upward pressure under the area where the starboard bulkhead bit is situated. (I haven't tried loosening those supports at all yet - I discovered this issue around 9pm last night, and had the sense not to start tearing crap apart late at night... :)

So, thoughts on this little conundrum?? It wouldn't be a huge deal to just build the 'hump' into the stringer, but that just feels way wrong - I'd rather see if I can figure out what's going on, before I start glassing a potentially new shape into the hull! :) I'll likely try loosening the wedges under the starboard-side 2x4 tonight, just to see if that drops that side down a bit. (I'm a little afraid of taking them all the way out, though, as they were put in place when everything was still together in the boat, so I assume that they're fairly true to the original shape of the boat?)
 
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Baylinerchuck

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3/16" ain't a whole lot of imperfection in a production boat. If it were me, I'd cut the center section out and build it flat. The factory churned these boats out as quickly and cheaply as possible so things are pretty inconsistent from one side to the next. This is mainly due, I'm told, to two different men working on either side of the boat simultaneously. My Chap was no exception to this. Cut it out and construct it right. Make it better than factory.
 

jim_s

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I suppose you're right - its a minor bit of work to remove those little remaining 'wings' (they're all of about 10-12" long on each side), and put new ones in. (GAWD I hate the thought of cutting and grinding more FG, though - I've been seriously rejoicing being past that stage! :)

I loosened up the support boards underneath tonight, and it didn't make even a tiny bit of a difference, so I suspect you're right - its just how it was originally built. I don't know how the stringers, bulkhead and floor were all put in - it all looked like it matched up, height-wise, when I was tearing it out, but then, I didn't take any close-up pics or such at the time - perhaps they made up the difference with some extra poly resin and chopper glass, or just threw down some extra filler or foam or such - who knows. Good to know that this isn't a particularly unusual situation, though! You're right 3/16" isn't a huge deal, but its one of those irksome things, when stuff doesn't line up with the reference string! <:)
 

Baylinerchuck

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That 3/16" has probably been there ever since the boat rolled out the factory doors......no one ever noticed. Now you have the chance to make it right.
 

jim_s

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You 'make it better than original' guys are gonna freakin' get me divorced! ;->
 

jim_s

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Ok, so I did what I should have done early-on when I discovered this little puzzle - I ran a string across the boat right beside these 'wings', and found that one side is, in fact, 3/16" taller than the other side. (Of course, the stupid-simple approach would have been to just measure the two heights, and compare them, which I finally did to confirm the string results - kinda bassackwards, I guess.... :) So, I just trimmed down the extra 3/16" from the taller side (had to take a wedge-shaped hunk off of the top, as the 3/16" was on the inner end of the remaining 'wing', and the outermost end was, of course, flush with the hull on the outer edge. Both outer wings of the bulkhead are now flush with the horizontal and longitudinal strings - things are good!

SO, that problem is now solved.

Back to thinking construction thoughts!!
 
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jim_s

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So, stringers... My stringers are 3/4", though a section of them are doubled up. For the single-width section, should the bottom of the stringer be cut at an angle to match (ish) the angle of the hull? (ie, the 'V' aspect of the hull) I pretty much won't be able to avoid either cutting an angle, or at least vertically staggering the doubled-up section, otherwise the inner doubled-up section (the doubled up section on the keel side of the stringers) would end up being up off the hull by a significant amount..

Also, how much room should be left for the epoxy/milled-fiber peanut butter, between the stringer and the hull? (I've read repeatedly that the stringer shouldn't directly contact the hull, but instead should sit on a layer of peanut butter or such, to provide a little bit of isolation between the stringer and the hull.

Is there any need or point in encapsulating the stringers in glass cloth (aside from putting a coat or two of epoxy on them, which I'll do for sure), before putting them into the hull, or should I just epoxy coat them, then tab them in, then glass them all the way over?

Lastly, any idea how much I should undersize my bulkheads, to allow for a layer of 6oz glass on them before putting them in place? (ie, 6oz glass wrapped around the edges, with a coat or two of epoxy, will take up a measurable amount of space, I'd imagine - I don't want to end up with bulkheads that won't fit between the stringers. Or, maybe I'm trying to make the tolerances too tight, and should allow a good 1/8-3/16" of wiggle room, and just trust the epoxy/cabosil peanut butter filleting material to make up any difference?

Excited to finally be to the point of cutting wood to put back INTO the boat!!! :)
 
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Baylinerchuck

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So this is what I did.



Leave a 1/4" gap between the hull and your wood components so you can push PB under them. This is called bedding the stringers. I also left enough of a gap between all my wood joints to ensure I could squeeze PB in there as well. I used chopped strands in my PB for added strength. I used polyester resin though, so I don't have many answers for you on epoxy.
 

jim_s

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Woodonglass - thanks for posting that link - I'd read it through before, but has sort of lost track of it - glad to have it again! (bookmarked it this time!!)

Baylinerchuck - Thanks for the pics and info - definitely helpful!

One other question - the sheet of 3/4" marine ply that I got had been sitting on 2 narrow boards (2x4's) at the lumber yard, to keep it off of the ground, but it developed a bit of a bow in it, from sitting like that for a few days w/ the center section unsupported (between when it was delivered, and when I picked it up). I need to cut two 52" long sections out of it for my stringers, and will cut to minimize use of any remaining bowed area, but if there is still some bow in the cut pieces, would I be better off putting a layer of glass on each side, to flatten it out (figure if I were to put it on a flat surface, glass it, weight it down so its held flat, let it set up, then do the same for the other side, it should come out very straight, and probably a fair bit stronger, to boot), or should I just do my best to make sure its fairly straight when putting it in (I could use the bulkheads to help hold it in a place, and in a straighter position), and move on?
 

Woodonglass

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If you use 2-3 stringer jigs like this...
stringerBraces.jpg
you should be able to keep em straight enuf when glassing them in the boat. If you lay the ply down flat with some weight on it over night it'll prolly straighten a bit.
 

jim_s

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Latest update - no new pics as of yet. 14 hours hunched over in the boat yesterday, and the stringers are now rejoined and glassed in. I went through about a gallon and a half of epoxy (yikes!) - between pre-coating the stringers and butt plates and laying down 2 layers of 12oz cloth over each stringer. I have a much better feel for mixing up the various consistencies now, and am slowly getting better at laying down fiberglass, though I'm also a bit discouraged at the prospect of getting a nice, smooth finish on the top of the deck - it'll be covered w/ a floor covering, but I'm hoping to get it as smooth as I can, so the covering (hydroturf) lays down nicely. One big take-home was that fillets can be made too small, but it seems its hard to make them too large! ;-)

I also fear that I'm going to need to grind down a little bit of my hard-fought effort of yesterday, as I ended up with a bit of a high spot in one area - not sure what happened there, other than I just built up too much cloth. (Its a joint where a stringer meets a bulkhead, and there's an extra layer of glass there from where staggered layups overlapped each other...)

Anyway, this was a big mental hurdle - the glassing thing is now no longer as much of a daunting task. (Aside from the whole 14 hour thing...)
 

jim_s

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Oh, also - despite my prior misgivings about using screws, I used screws. (coated deck screws, as suggested). Given that I was joining to original front and rear stringer pieces using butt joints, I was having trouble getting and keeping everything lined up in my dry fit stage - I knew this meant real trouble when it came to actually it for real w/ epoxy. So, I used the coated screws, pre-drilled all the holes, and labeled all the parts, so when it came time to put the coated pieces together and epoxy it all, it was like assembling a kit - went right together, lined up perfectly, etc. Glad I was talked into using the screws!!
 

jim_s

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Yeah, sorry, once I started swimming in epoxy, it seemed that touching my phone would be a Very Bad Idea. :) My legs are absolutely killing me today - I must've made 100 trips up over the side of the boat (sitting on its trailer) yesterday. Given that about 80 of those 100 times, I was carrying something wet and sticky, its a true miracle that I didn't end up getting epoxy all over the gelcoat in the process! (I got a bunch of cinderblocks today, to hold the floor down when I epoxy it in - next logistical task is figuring out how to get 10 cinderblocks up into the boat w/o scratching the heck out of the gelcoat. I'm thinking a step stool and a fender cover made for working on cars - I probably should have thought about that before starting the epoxy job yesterday!)
 

Baylinerchuck

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I use an old blanket draped over the side. It's worked well to rest heavy items on, as well as keeping sticky fingers off.
 

jim_s

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Dry fit of floor and new storage hatch - starting to look more boat-like!
 

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jim_s

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So, after all of the discussion on how to best handle the seat base mounting, I took a sort of hybrid approach. To be completely honest, it was driven in large part by simplicity of putting down HydroTurf floor covering foam - it apparently doesn't adhere well to curved/lumpy surfaces, and I didn't want to leave the exterior riders exposed, either. So, while not easy to tell from the picture, due to bad lighting/angle, I filleted and glassed the mounting rings to the bottom of the (also glassed) floor. Its a healthy cabosil fillet internally and externally, then 2 layers of 6oz cloth, and 3 fairly generous applications of epoxy below, between and above them. It should be water tight from the bottom (ie, not allowing water to get through the floor, into the sealed compartment, from the top). On the top, I drilled oversize holes (before glassing the floor), filled them with cabosil PB, glassed over them (top & bottom), then drilled through the cabosil 'puck', once everything was fully set. Between the puck and the glass on the top and bottom of the floor surface, the anticipation is that water will not find its way to the wood floor through the seat mounts. (I also plan to 4200 the heck out of the seat base bolts when I finally put them in, so hopefully no water will even manage to get down into the bolt holes). I suppose we'll see how The Plan plays out over time...
 

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