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.

Top-Gun

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

glassdave

iTrader: (1)

many many many Donzis do that . . . mine included best way is to fully tab (fiberglass) the deck and hull together but Donzi did not make that boat to be easily worked on. Next best thing is, as you've already stated, through bolts. If you can access the inside your on the right track. If theres silicone or 5200 in the joint already there not gonna be much you can do about that other then rely on the through bolts. Make sure you use nylocks

ZP'd

No backing strip or nothing besides screws driven thru the glass on hull/deck? If no backing plate of any kind definitely do so.

glassdave

iTrader: (1)

If you want to use a backing strip you will need to also drill/nut an bolt the 10-24 rubrail hardware through them, otherwise the plates will put a lot of pressure on the 1/4 20's as they are already going to be countersunk in the deck layer so they will have a head start pulling through. Ideally the best is still to fully tab the deck and hull if ya can.

Black Baja

iTrader: (2)

Man I wish my zx had cracks like yours. I would have had the thing in the water a month ago. Mine had more area with cracks than without.

Top-Gun

Thanks for all the replies, I'm definitely feeling better about this problem!

I think I'm going to go the 1/4-20 thru-bolt route; Glassdave hit the nail on the head this hull is a PITA to work on inside. Since the motors never been apart and the gas-tank has never had any service I want to leave the deck as easy to separate as possible. My current plan of attack is to drill all new holes on 6" centers and countersink the deck to separate the gel-coat from the bolt head and shank. Hopefully that should keep new cracks from forming from the new holes/fasteners. I'll then go around and slightly open up the gel-coat at each of the rub-rail screw holes to clearance them as well and take the stress off.

My plan for the time being is to just affix the rub-rail back with the existing #10 screws since I'll have to slowly pick away at the gel repairs. Eventually I could go back and replace the #10 screws with #10 bolts/nuts/washers to further beef up the joint.

I'm guessing the process of V'ing out each crack and filling/sanding/polishing is going to be brutal, but are there any tips/tricks to make this repair easier?

Thanks again.