Bulkhead replacement

[landlockvasailor]

Landlocked Sailor Looking For A Salt Breeze

Installed new marine plywood stringers and bulkheads. I intentionally left 1.5" gaps in stress areas rather than glass in. Considering using a spray foam for these areas. Not an issue of support, only to fill gaps. Any pros or cons would be appreciated

Tom Morris

[Faster]

Unclear what you mean by your gaps... gaps in tabbing? gaps between hull and stringer/bulkhead edges?

Pictures would help..

[landlockvasailor]

gaps between hull and stringer/bulkhead edges

[Faster]

Unless you're using a rigid foam to "soften" the bulkead edge when you're tabbing, I don't see the point of these gaps... seems to me the more rigid the entire structure is the better off you are. Limber holes for drainage are fine, but wholesale gaps? I don't get it....

[sailingdog]

Faster-

You don't want the plywood of the bulkhead touching the hull, since that will cause a hinge point for the hull to flex and fatigue at.

Landlock-

Don't use a spray foam. Use a high-quality, fairly high density, polyurethane foam, either dinvylcell or airex. Then glass over the foam to tab in the bulkhead.

[Faster]

Originally Posted by sailingdog

Faster-

You don't want the plywood of the bulkhead touching the hull, since that will cause a hinge point for the hull to flex and fatigue at.

SD - that's what I was alluding to when I mentioned the rigid foam to "soften" the bulkhead edges... I'm familiar with that technique.

I get the impression that Landlocked has deliberately left large gaps here and there, tabbing in between and now wanting to fill the "gaps" with some spray foam... without pics it's hard to imagine just what's up.

[sailingdog]

My guess is that he used some sort of foam when he did the initial tabbing and glassed the bulkhead in place, but didn't lay down a complete strip of foam between the bulkhead and the hull.

SPRAY FOAM is not an appropriate material to use, since it has very little resistance to absorbing water, and almost no strength.

[landlockvasailor]

Thanks for the corrections.

I will use the rigid foam and tab to the fiberglass. I was apprenhensive of bringing the wood flush with the glass given the possible flex and grinding. Though the edges of the wood have West on them, I felt a gap of 1/2" would prevent.

Thanks
Tom

[sailingdog]

De nada... BTW, if you cut the foam into a trapezoidal shape, it will help you with the tabbing...since fiberglass doesn't do tight corners well.

_
/_\

The foam will help create a fillet for the glass to adhere to.

[landlockvasailor]

Ok, that make sense. As you see I added a picture of the o'day 22 as it sat in Missouri. Now that I know how to upload, will do a better job when having a question. Pictures as the gentleman shared would help !
Tom