Deck to hull joint..

[CCrew]

Me again.. Looked a bunch of places and can't really find anything definitive..<br /><br />When installing the deck, what's the best way to deal with the deck to hull joint when there's no defined place for it in the hulls layup? If I just square cut the ply, there's basically a joint that looks like |/. My thought is to take a router and scarf the deck edge so that it looks more like //, but that takes a bit from the strength at the edge since it's basically taking some of the ply thickness away. <br /><br />As always, opinions appreciated!<br /><br />Roger

 

[JB]

Re: Deck to hull joint..

I think you are on the right track, Roger. The // joint will have larger surface to bond and make a stronger joint than a ]/ with a filler.<br /><br />If you are using marine grade ply for the deck voids in the ply wont be a problem, though they might in plain CDX. Even with CDX, though, I think your solution is the best.<br /><br />You might consider a solid wood "shelf" and inch or so wide under the ply, also // to the hull.<br /><br />Good luck.

 

[BillP]

Re: Deck to hull joint..

I agree, leave a lip of the old floor (assuming it is good wood)and bevel the edge at 45, 60 or whatever. Bevel the new floor to match and the glue the joint...then glass. Like JB says, a wood cleat can be also be glued/screwed under the lip to give extra support. Somewhere on the web a guy did a Mako this way and gave great pics and descriptions. He left approx 8" all around and did the bevel/cleat construction. Maybe someone else knows where the link is to that...I can't remember.

 

[mellowyellow]

Re: Deck to hull joint..

had a friend who used some 1x stock and epoxy'd<br />it to the outer hull and put the plywood on top<br />with ss screws. I like the idea of being able to<br />remove the floor easily down the road.<br />as JB already described...

 

[msmorto]

Re: Deck to hull joint..

I agree with the bevel, but I disagree with another piece of wood cleat, That would mean another way for water to get trapped and ROT. There is not that much span between the stringer and the side of the hull that requires a cleat, if you remember when you cut the floor out how hard it was to pull it apart if you did not cut all the way. Just glass it good to the hull.<br />Thats my opinion.

 

[1965MT]

Re: Deck to hull joint..

I looked at doing a cleat, but that would be a lot of work for low payback, IMHO. I am planning to scribe the sole elevation to the hull. There will be two scribe lines that represent the top and the bottom of the plywood sole. Then I am going to scribe both lines from the hull back onto the plywood sole. I am going to cut the sole to the outer line and then use the belt sander to bevel to the inside line. It won't be perfect but it will be close. The next step will be to epoxy 1/2 width of fiberglass tape to the bottom of the sole. When I install the sole I am going to epoxy the other 1/2 of the tape to the hull. <br />I am going this route for two reasons, 1.) I don't want to waste epoxy making a fillet, even though that would be strong enough, and 2.) I don't want the epoxy to run through the joint, this would be a waste of epoxy.

 

[mellowyellow]

Re: Deck to hull joint..

while I agree with you in theory msmorto, I think<br />it's better to design the floor with the idea that<br />water IS gonna get in no matter what you do.<br />with proper planning/drainage/construction it<br />shouldn't cause problems with rot. the secret<br />is good drainage IMO. another question: if the<br />hull was 100% water tight, would that cause it's<br />own problems due to lack of ventilation?

 

[BillP]

Re: Deck to hull joint..

If you use epoxy it will bond butt joints just like new wood, so the bevel method works fine without a cleat. But a cleat can help give the new floor a footing and make a more substantial joint. It can also keep the resin from draining before it kicks off. Even heavily thickened (to buttery consistance)epoxy resin thins during the initial kick and can drain in spots if it has a place to go. The cleat can be epoxy coated and set in epoxy for waterproofing, just like the floor. I don't use cleats on floor jobs either but only because the application has never reared it's ugly head to do it. Aside from that, if pressure treated wood (CCA) is used you don't have to worry about rot either.<br /><br />Mellowyellow...condensation still occurs under a sealed floor. Rot can happen if the condensate continually gathers and keeps an area of wood wet. Venting just speeds wicking the water back into the air before that process starts. I guess the ideal setup would be to purge under the floor with GN2 (gaseous nitrogen) and put the drain plugs in quickly. This displaces moisture and oxygen and would eliminate underfloor rot if kept airtight.

 

[CCrew]

Re: Deck to hull joint..

Thanks guys, I appreciate it. <br /><br />I'm not particularly fond of the cleat idea, as I can't see a really good bond to the hull, and the angle's so extreme that there's still really no edge to screw to, although I can see workarounds. Personally I'm kind of preferring the router idea and scarfing it back. There's no wood left on the edges to do a joint, so that's pretty out of the question. Sounds like msmorto, 1965mt and I are along the same ideas here, I guess since we're looking at the insides of our bare hulls and they're all the same...1965mt's tape idea was exactly what I had planned ( I actually already have the lines scribed) but I was thinking a couple strands of unidirectional roving to make up the gap rather than just trying to backfill . regardless looking at the same boats does give a bit of perspective! <br /><br />MelloYellow.. I have to ask one thing of you or others..<br /><br />While there's a lot of value to things like limber holes and the like, isn't the use of them where they didn't originally exist opening the possibility of actually introducing water from the bilge where it wouldn't be normally? Thought here that if you've sealed the area at the bottom, glassed the stringers, and encapsulated the deck and filled the area with foam, you've pretty much eliminated most of the chance of condensation, since condensation needs air space to form. Eliminate that air space and haven't you eliminated most of the problem?<br /><br />Thanks!<br />Roger

 

[Boomyal]

Re: Deck to hull joint..

Would it be possible for any of you guys to sketch out what you are talking about. I'm getting ready to tear the floor out of my boat and one of the questions I could forsee was what I think you are all speaking of. Thanks

 

[mellowyellow]

Re: Deck to hull joint..

rodger unless it's a vacuum, air (with moisture)<br />will get in. I still stand by proper drainage.<br />i guarantee water will always take the path of<br />least resistance. up to you to let it take it's<br />natural course. just my .02.<br />but either way, done right, will outlive us both.

 

[CCrew]

Re: Deck to hull joint..

Mellowyellow...<br /><br />I understand completely and please don't think that I'm thinking your way is wrong... I'm just wondering if there are two schools of thought conflicting here. <br /><br />I'll grant you that yes, you'd need a vacuum to insure that nothing entered which is nice in a perfect world. We all know this isn't a perfect world we're dealing with. <br /><br />Common sense would say to put limber holes in the stringers to allow any water on the outsides of the stringers to be able to drain to the bilge, and that the best place would be at the very rear, which is the lowest point. But, that also defeats the purpose if you do something that fills the bilge (forget drain plug, bellows failure, etc) because that lets water possibly into an area that wouldn't see it normally. <br /><br />Would the best of both worlds be to put limber holes in using tubes, and use drain plugs in except when the boat was bow high in storage? I dunno..<br /><br />Roger

 

[mellowyellow]

Re: Deck to hull joint..

a good debate for sure...<br />MY perfect hull would have the flotation foam<br />above the bottom and sealed enough to let water<br />flow freely to the bilge.<br />since there's snow on the ground, all I got right<br />now is theory...

 

[crab bait]

Re: Deck to hull joint..

my last built boat was a 'stich & glue'.. the instructions called for a rough cut floor..at least a 1/2 in. gap allthe way.. <br /><br />a tite/snug fit was not wanted an un-desirable...<br /><br />said to/i did,, apply thick handmade epoxy putty..usin' 75 % silica,, 15 % microballoons an 10 % milled fiberglass..<br /><br />layed putty,,, than mooshed layed the ply floorin'..<br /><br />what mooshed over ,,i used to make fillet..<br /><br />a layer of 8 in wide biaxial cloth layed in half.. half (4 in.) on the floor.. 4 in. on the hull.. <br /><br />than layed another biaxial... 6 in. wide .. again in half ... 3 in. an 3 in.. <br /><br />as per to have a 'stair stepped'/ tapered effect ... so as to better'feather edge' <br /><br />then mix up more putty to use as 'spackel' to hide to the cloth.. an sand smooth to hull & floor..<br /><br />careful not to sand into the cloth as to degrade the strenght of the biaxial..<br /><br />see,, the tite fit was undesiriable cause it takes the putty to surround the joint as to be a component in the 'composit'..<br /><br />AMMENDMENT ::<br /><br />when making 'SPACKEL' putty,,, use a 75 % microballoons an 25 % silica mix.. this is so it can be sanded readily... if not,,( boy,,are you in trouble ),, it'll never be sanded..!!

 

[msmorto]

Re: Deck to hull joint..

Since water tight and air tight is IMPOSSIBLE TO ACHIEVE especialy with drain holes in the stringer at the bilge area, I plan to PREFOAM under the floor with a temporary piece of plyw'd<br />and wax paper, about 1 1/2" below the permanent<br />floor, so that air can circulate with the bilge blower, JUST A TOUGH

 

[CCrew]

Re: Deck to hull joint..

msmorto..<br /><br />You planning to use thicker than the original 1/2 ply? I looked at 1/2, and without the foam directly under it as additional structural support I wasn't impressed by it's ability to flex..<br /><br />I do like the ply/waxed paper idea though, hadn't thought of that. I was going to forstner bit holes in the ply, then use sliced hardwood dowels to plug the holes w/resin and the plug. Sand it flat to the top deck and them glass the whole thing<br /><br />-Roger

 

[1965MT]

Re: Deck to hull joint..

boomyall, I will take some pictures of the procedure next week.

 

[msmorto]

Re: Deck to hull joint..

CCREW:<br />I will be using 5/8" ply'wd. The original was 5/8". With my idea you don't have to drill holes in the floor since the foam will aready be there. When I pulled the original floor the foam did not completely filled the void under the floor, and there was no give to the floor, I weight about 195lb and I steped on it many time and there was no give to it. My floor and stringer rotted mainly near the seat boxes and at the stringer cross bracings thats where the water could not escape.<br />I will be driling a 1" hole near the lowest point of the seat boxes and the cross-bracing. Again I will PREFOAM the boxes so that there will be some space between the bottom of the foam and the floor for drainage and air circulation. Also when you PREFOAM, you control the installation and where you want the FOAM to be. Not like drilling holes in the floor and hope that the FOAM is going where you want it. (All guess work)<br /> <br />Mario

 

[Outrage 19]

Re: Deck to hull joint..

This might sound crazy but has any body thought about using that new decking material that’s not wood?

 

[Boomyal]

Re: Deck to hull joint..

Ok, no answer from outrage so I'll change my post!<br /><br />Thanks 1965MT. I'll be anxiously awaiting your pics.