What causes gelcoat damage?

[TXDeer5layer]

Just got done spending 3k on a new bottom job for my 87' overnighter: started out as just having the bottom paint sanded off, they found a bunch of hairline cracks and a few chips in the gelcoat about the size of a quarter. So they had to fill in the cracks/chips and respray with gelcoat.

My question is: What could be the cause of the cracks and chips? Sitting in the water too long? Or could it be from impact? Old age? My guy said the fiberglass looked good by the way.

I want to know what i can do to prevent this from happening again. I keep it on a hydro lift so it stays dry and doesn't sit in the water but i bought the boat 2 years ago so who knows what the previous owner did. I DO know they sprayed the keel with bottom paint instead of properly fixing the cracks.

 

[DennisG01]

Gelcoat is relatively brittle. It's main function is to waterproof (although it's not 100%) the glass and make the boat look nice. It does not add structural component. In fact, if it's laid on too thick it is more prone to cracking. Obviously impacts can cause damage. Spider cracking can be caused both by an impact and improper hole drilling/screwing. Another thing that can cause chips would be an air void. Water intrusion can cause blistering, and then the blister can pop with an impact or hard loading (although the popping part is rare). Obviously there's no way for us to tell what caused your issues, but from the short description it sounds normal and what one would expect over time.

Why did they respray the gelcoat just to cover it up again with bottom paint? I'm not following with what you said about the keel.

As far as "care" goes... keep it off the rocks!

 

[gw204]

Hairline cracks in the hull bottom can show up when the hull starts to flex. Hulls start to flex when their stringers are rotten. Based on what you said in your other thread about stringer rot I would have that boat thoroughly checked out...

 

[TXDeer5layer]

Thanks for the info. I will have it checked out, any recommendations on how to find someone who can survey it?

 

[TXDeer5layer]

Gelcoat is relatively brittle. It's main function is to waterproof (although it's not 100%) the glass and make the boat look nice. It does not add structural component. In fact, if it's laid on too thick it is more prone to cracking. Obviously impacts can cause damage. Spider cracking can be caused both by an impact and improper hole drilling/screwing. Another thing that can cause chips would be an air void. Water intrusion can cause blistering, and then the blister can pop with an impact or hard loading (although the popping part is rare). Obviously there's no way for us to tell what caused your issues, but from the short description it sounds normal and what one would expect over time.

Why did they respray the gelcoat just to cover it up again with bottom paint? I'm not following with what you said about the keel.

As far as "care" goes... keep it off the rocks!

No they didn't put bottom paint on it, it HAD bottom paint and i wanted it removed so they sanded it off, found the gelcoat cracks and decided to respray it with gelcoat.

 

[DennisG01]

This is the part I didn't understand: "I DO know they sprayed the keel with bottom paint instead of properly fixing the cracks."

If they drilled the end of each crack, then ground out the cracks, filled with epoxy and then put bottom paint on simply for aesthetics (to cover the epoxy) then that is OK - from a functional point of view.