Advice on Deck and hull/deck joint repair

FYI I've also posted this same query on Sailnet.com and am posting here hopefully to to get a more responses.

I have a three part question and would like several opinions.

I am replacing the soft deck in my Balboa 20 which is best described as a swing-keel pocket cruiser. Water infiltrated several places where previous owner and even the factory did not protect the core when fastening through-deck. The hull-deck joint is NOT the usual flange-and-lid arrangement but a sort of cookie-tin lid. (See Figure A.)

Since the bulk of the deck build is in the upper surface and since water has infiltrated the fiberglass skin below the core in several places, I have removed all of the old glass skin and plywood core from below. Now, it turns out, the hull deck joint is loose in several places. It was originally held together by some kind of adhesive (5200?) and a skillion 3/16 bolts that mount the rub rail. \

Separating the hull and deck sufficiently to clean the joint and make and effective application of new adhesive is out of the question.

Please consider the repair options shown in attached Figures B and C.

In Figure B I've shown the hull-deck joint glassed together (blue) then glued in the core and additionally supported by a glass flange (red) before applying a finishing layer (green) on the inside overhead.

In Figure C I've skipped explicitly glassing the hull deck joint. I've simply glued the plywood core in and then installed a glass flange for support (red) and the overhead finishing layer (green). The hull-deck joint is somewhat stabilized especially when you consider the rub rail screws, but not as good as in option B.

QUESTION 1: Option B or C? This boat never sees heavy seas but trailering (especially loading and unloading) can result in significant stress.

QUESTION 2: What weight of cloth or biaxial tape and how many ply for glassing the hull/deck joint (blue) in Option B?

QUESTION 3: What weight of cloth or biaxial tape and how many ply for providing a flange for the plywood core in Options C & B

Re: Advice on Deck and hull/deck joint repair

hi......welcome to iboats.....

this is the best place on the net for any boat building questions....

there are a few questions i want to ask.....

im starting typing now.....so if you can ...stick around so we can get you helped as fast as possible

Re: Advice on Deck and hull/deck joint repair

ok.....first off......the joint is a standard shoe box joint.

the flange joint you are talking about went away 40 years ago.
the shoe box joint is far faster in production building.

ok....as far as glassing the joint.....dont worry about it.....in fact....you dont want to...

the joint it self is sealed with 3m5200 and riveted every few inches..

you say the core of the deck is rotten......

normally there is no core in a deck....just glass.

however if there was....the new core MUST be properly laminated to the glass skin....or problems will occur.
that is hard to do in a upside down situation..

it is the same thing as laminating a new transom into a hull. you need pressure and clamping to get a proper bond.

how did you do it?

the what you are now trying to do ...is protect the core.....that is done by encapsulating the core.
that will be done by using a thickend resin around the edges....and a layer of csm.

the 1708 full wrap you are thinking of is way overkill.

Re: Advice on Deck and hull/deck joint repair

Sorry, I thought I'd replied much earlier? but reply didn?t post for some reason. Here it is again.

Perhaps I was unclear? the adhesive (5200 or whatever) in the hull-deck joint has failed in several locations. The only thing holding it together there is the rub rail screws (sorry, no rivets). In several places I can lift the deck off the hull by hand. I believe it needs to be glued back together. The question is the most practical method for accomplishing this.

The deck did indeed have a plywood core that I spent the weekend removing. Calling it "rotten" was perhaps an overstatement. The plywood itself was actually mostly sound but was wet through and through and was delaminated from the upper and lower glass skins over several large areas.

I haven?t yet put in the new core. Haven't even bought it yet? I'm seeking advice first. I do intend to seal the wood first as you suggest. To glue the core to the upper skin I intend to use high viscosity epoxy thickened to peanut butter consistency with chopped cellulose. I will apply to both upper surface and core then press in place with shoring from below and by inserting screws from above to pull the wood up to the skin.

I've now read of others using light cloth or csm for the lower skin so I guess 1708 would be overkill but I do still want the support of a glass flange around the edges.