22 ZX Deck/Hull Joint

[Top-Gun]

I've got a 1997 Donzi 22 ZX and its steadily been acquiring a large number of gel cracks coming out from under the rub rail. I removed the rail today and think I found the root cause. The hull/deck joint is not rigidly bonded placing stress on the rail screws which are then starting cracks from most of the screw holes. To make matters worse, it appears the factory just drove the rail screws in through the deck and hull without any countersink/bore on the deck.


Before I tackle trying to fix the cracks, how do I go about properly reinforcing the deck joint? I was thinking of drilling new holes sized for 1/4-20 machine screws between all of the rail screw holes and thru-bolting the deck and hull with washers and nylon nuts. I'd probably have to countersink the deck to get the screw heads so they don't interfere with the rail. Then I would counterbore all the rub rail screws just enough to clearance the gel from the screws. Does this sound reasonable or is there a better way?


I can't see any way of getting adhesive into the joint without removing the deck completely, plus I'd like to be able to get the deck off in case I ever need to get to the gas tank, etc.


Any advise is appreciated.

[gcarter]

Maybe some pictures?

[Top-Gun]

Snapped a few shots today of what I'm dealing with;

[gcarter]

It's entirely possible that the original gel was sprayed on too thick.
If that's the case, there's not too much to be done except refinish the area.
Is there access to the inside of the rail, or is there a liner in there?

[biggiefl]

Call the factory!

[Top-Gun]

There is access to the rail inside in most places, need to remove all the panels in the v birth but that should expose a majority of it.

ive phoned Donzi before but they weren't much help, I agree that the gel is definitely not right on this thing but I don't think running screws through the gel without clearancing the holes helped matters.

As far as beefing up the deck/hull joint, is it worth thru bolting it with 1/4 bolts/nut/washers before I start grinding the cracks and repairing? I think if I stiffen up the joint and then countersink all the holes it should serve to prevent the stress at the fastener locations that started the cracks. You can see where the factory installed large diameter Phillips screws with countersinks and none of them have cracked.

[gcarter]

I've always been a believer in through bolting. On Classics, the joint is screwed together w/flat countersunk headed wood screws in between the holes in the rail. I believe in through bolting using 1/4-20 countersunk flat head machine screws, backed by fender washers and Nylock locking nuts for the joint holes between the rail fastener holes, and #10-24 machine screws, fender washers, and lock nuts for the rail fastener holes.
Again, on Classics, these are larger than stock fasteners, do very well, and don't loosen up.
I don't like adhesives in the joint. Ya never know when the thing will have to come apart.

[biggiefl]

I agree with George about adhesives. 5200 on a console on a boat i bought. Took off part of the gel removing it to put in new cables. What a chooch!

[Morgan's Cloud]

5200 , the 'other' invention of the devil .

[gcarter]

Looking at your pictures again, the 1/4" machine screws need to be on about 6" centers.
I think you'll end up w/between 200 and 300 fasteners.

[Pat McPherson]

I seen boat with bolts thru the rub rail and deck join with washers and nuts on the inside. The rub rail insert would have to be large enough to cover the bolts.