Found bubbles on bottom of boat where it sits on carpeted bunks. Getting it repaired but should I switch out bunks to plastic ones?

Same here. Ive noticed the same problems.

What you have is generally called "gelcoat blisters." Not a great situation and changing bunks won't solve the problem. Hopefully Glassdave will chime in with one of his very good descriptions of the problem, the causes and the possible solutions.

You have Gelcoat Blisters...pretty common for boats that stay in the water all the time. Switch to Marine/Indoor/Outdoor Carpet for the bunks and consider weep or drainage holes in the bunks for the water to run out...trapped water is the culprit.

+1

I'd look at taking a router and cutting a couple-3 shallow drainage channels end-to-end in the top of the bunks. With a few holes drilled in each of the channels, all the way through the bunks. As sprink said, the water needs to get out or it's going to keep getting absorbed through the gel. It'd be interesting to know whether the blisters go away quickly if you block the boat up such that the blisters are exposed to the air. If they don't, you may need to make both bunk mods and do some repairs on the glass. Or at least leave it blocked up, so it dries. Others like GlassDave will know more about the boat side of the situation and what you'll need to do there.

They won't dry up on their own. The gel absorbs water and make the blisters. They have an acid type liquid in them from the "osmosis" that creates them. Lots of boats get them. Most of the time they are cosmetic and just at the surface but you still should have them repaired to keep them from going further. My boat has some as well that I'm getting taken care of in the spring.

I think it's actually an "it depends" and you have to test and see what happens. Lots of them disappear on their own. Some within hours, some not. I've seen some that took years on the hard to dry out. One of the biggest questions is how fast they appear and disappear. There are boats where you can splash them for a day or two or four and the whole bottom will blister, and within hours of getting out out of the water they will vanish. The other question when they disappear is where the water went. It may go right back out of the gelcoat into the air (good). It, or some of it, may go into the glass (very bad).

I expect the cycle of blisters inflating and deflating will mechanically weaken the gel and eventually spots will just start to fall off. The real solution may be to let the hull dry out thoroughly, sand, and then barrier-coat. There are barrier coats for boats that live in the water all the time. That's very labor-intensive as they build up a LOT of layers--overkill on a trailered boat.. There are lighter barrier coats that can go on with a coat or two and should take care of the issue IF the surface is properly prepared. My guess is that even if the hull in question dries out and looks completely normal, if you sanded it to prep for a barrier coat, you'd see a few spots of gel rip out during sanding and need patching, where there had been blisters before. I'd also expect that the spots you patched would be even more likely to blister afterward, unless you barrier-coat. My understanding is that patch-additive for gel makes it less-likely to keep water out.

Does it sit outside on the trailer???? Possibly water running down the sides from dew and rain and the bunk carpet is often wet a lot and doesn't dry out.

Most people I know with boats on lifts have plastic/composite bunks.

These, http://www.overtons.com/modperl/prod...n-Kit&i=714761 , and similar products look intriguing. Has anyone used plastic glide-ons?

Installed boxed plastic slides on 2x6 bunks 13-14 yrs. ago. Lumber exposed at bottom of slides looks factory fresh and less troublesome than carpet which stays wet. One of the best upgrades to the trailer other than disc brakes. Plastic has angle grooves to drain quickly. Pic is similar to what I have bought at Bass Pro.

http://www.easternmarine.com/self-ce...-white-86296-0