preventing stress cracks?

[skers85]

Just wondering if anyone had some good ideas on how to prevent stress cracks on the gel coat from tower install

[kartman]

chamfer all the holes.

[INVERTCRASHER]

Chamfer holes. Basically you are grinding out the edge of the hole going through the boat. I think this help but over time but most towers will eventually crack gel coat. Cost of doing business!

[Suprahunter]

Stress cracks are caused by movement or flex fiberglass will tolerate some flex but the gel is hard and brittle it will crack. Some boats have thin fiberglass on the upper deck there may not be anything you can do to prevent stress cracks. Here is what I did on my 89 Supra Sunsport.

Chamfer the holes so the stress is on the fiberglass not the gel cote. Reinforce as much as possible under the deck where the tower legs attach.
I used 3/4'' plywood covered with fiberglass and then epoxied them to the under deck. I also made larger aluminum backers out of 1/4'' thick material.

Its been 4 years and no cracks.

I chamfered thr holes using a countersink bit you can see the different colors of gel used on the top deck


Bigger backing plates

[INVERTCRASHER]

i thought about a ring of rhino liner on inch or so larger that the foot of the tower, Never tried it tho