Is this hull damage or bad bottom paint

sbw1

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Oct 10, 2006
8,183
West Michigan
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A friend asked me if I had seen a boat for sale that he was interested in possibly owning. The pictures on this thread are of one side below the water line. The rest of the paint looks good with no cracks. This area is about 8 feet long and a foot tall. Any experts out there have experience with this kind of failure and have with a good, informed sense of what happened?
 
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Definitely would want to remove the bottom paint to the gel coat to make sure the cracking was limited to bottom paint. Also if you can see the inside wall you can see if there is evidence of a repair or delamination.
 
Definitely would want to remove the bottom paint to the gel coat to make sure the cracking was limited to bottom paint. Also if you can see the inside wall you can see if there is evidence of a repair or delamination.
Good point about looking under the bottom paint. Inside the boat is a head and galley in that area. So....maybe no easy access. I wonder if there was hull damage because there is a stern thruster on the transom. Suggests a skipper who needed help docking a boat that should be a piece cake to handle. Boat has big props that are set wide apart.
 
We occasionally see that "cracking". In every case it has been the result of "cosmetic bottom jobs" done on the cheap where a quick (meaning minimal sanding) additional coat of bottom paint is rolled over several previous coats of paint. The water line looks great but it is a thin coat of antifouling which wears out or gets covered by slime or algae very quickly. THe rate of expansion for bottom paint is significantly different than FRP structures, so after a winter with a lot go temperature changes, the cracking appears.

I'm not a lot worried about there being problems under the paint in the gelcoat or FRP because that type of cracking in gelcoat would only be associated with physical damage and an improper repair which should be obvious to a decent surveyor. Besides, to fix the cracking paint, you will need to remove almost all of it by sand or soda blasting and you can see exactly what is underneath.
 
We occasionally see that "cracking". In every case it has been the result of "cosmetic bottom jobs" done on the cheap where a quick (meaning minimal sanding) additional coat of bottom paint is rolled over several previous coats of paint. The water line looks great but it is a thin coat of antifouling which wears out or gets covered by slime or algae very quickly. THe rate of expansion for bottom paint is significantly different than FRP structures, so after a winter with a lot go temperature changes, the cracking appears.

I'm not a lot worried about there being problems under the paint in the gelcoat or FRP because that type of cracking in gelcoat would only be associated with physical damage and an improper repair which should be obvious to a decent surveyor. Besides, to fix the cracking paint, you will need to remove almost all of it by sand or soda blasting and you can see exactly what is underneath.

The bottom paint looks somewhat fresh. The boat is on a trailer and has been outside for awhile in freezing temps and has also seen some sunny warm days in the past month. Just showed up, so we don't know where it spent the winter. Paint may have failed recently.
 
I don't see in anything in those pictures that worries me from structural standpoint in regards to the actual boat. There are no obvious points of impact in those cracks. I agree with Frank - it looks like a quick coat of bottom paint was put on for the sale and it didn't play well with the underlying gelcoat. And that area may have spent time in the sun right away and caused (at least hastened) that cracking. But it appears purely cosmetic to me.
 
I've seen that happen when cheap hard bottom paint is applied in cold weather. The bad part is that it's going to be under whatever you paint the boat next with. I doubt there's anything wrong with the boat just improperly applied paint.
 

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