Cobaltchat.com

I have somewhat new to me 2003 Cobalt 262 and last weekend we loaded on a ramp that wasn't very level. The boat sat a few inches off center and revealed a good bit of blistering where the bunks would normally be.

I didn't even know this was an issue, but now understand it does sometimes happen with carpeted bunks.

I've seen conflicting comments about this being a safety/structural issue. What do the folks here think? Would you not use the boat until this is repaired? Is there a possibility of fiberglass damage? For what it's worth, we don't wet slip, so it's generally not in the water for more than a few hours.

Thanks in advance for your feedback.

Gelcoat can blister like that if it absorbs water or water gets behind it. Cobalt uses a water barrier layer between the gelcoat and fiberglass now, but I don't know when that started or how effective it is from keeping this kind of thing from happening. My guess is that the bunk carpet holds enough water that blisters form where the boat contacts the carpet.

Gelcoat repair isn't rocket science - see threads like this one for example: https://www.cobaltchat.com/viewtopic.php?t=5278

I'm sure others with more experience will chime in too, hopefully with good news.

jhnmdahl wrote: Mon Jul 21, 2025 2:48 pm Gelcoat can blister like that if it absorbs water or water gets behind it. Cobalt uses a water barrier layer between the gelcoat and fiberglass now, but I don't know when that started or how effective it is from keeping this kind of thing from happening. My guess is that the bunk carpet holds enough water that blisters form where the boat contacts the carpet.

Gelcoat repair isn't rocket science - see threads like this one for example: https://www.cobaltchat.com/viewtopic.php?t=5278

I'm sure others with more experience will chime in too, hopefully with good news.

Thanks for the info, jhnmdahl. I agree it was likely the carpet, since the blisters are only where it sits on the bunks. May consider switching the bunks to GatorBak.

I did find this article which is somewhat reassuring. Confirms that the blisters may effect resale but shouldn't be a structural issue in the long term. Something to address in the offseason, I suppose.

https://www.yachtsurvey.com/BuyingBlisterBoat.htm

Yes we had those blisters on our 263 & 262 bottoms. It’s not structural. Enjoy the boating!

I had never heard of gelcoat blisters happening only under carpeted bunks. I learn something new every day.

AsLan7 wrote: Tue Jul 22, 2025 1:20 pm Yes we had those blisters on our 263 & 262 bottoms. It’s not structural. Enjoy the boating!

Thanks, Aslan. I appreciate your feedback!

Without seeing it more closely (and smelling the blisters), I can't say for certain, but I'm confident that those are due to voids in the lay-up during production. Even in Cobalts, it's not uncommon for there to be small sections of very small voids between the gelcoat and the wetted chopped strand mat that form the outer layer of the hull. When the boat rests on those voids (on the trailer bunks), they'll break open, revealing the voids beneath it. It can be repaired by a reputable fiberglass shop or you can attempt it yourself. You'd have to slightly grind out/chamfer each one of the voids, sand lightly, and apply a structural filler/epoxy resin that you then sand down before applying gelcoat to finish it.

Those tiny voids aren't structural problems, especially for a trailered boat. If you leave it in the water for a season at a time, I'd consider the repair need to be more timely to prevent water from getting into the lay-up. Gelcoat and fiberglass are hydraulically conductive, so you'd need to consider creating a waterproof barrier using an epoxy barrier coat.

"smelling the blisters"

What does that tell you?