Hull Blisters under trailer bunks

[CruisinGA]

I noticed hull blisters on my 2001 X9 from carpeted lift bunks. I removed the carpet and installed plastic bunk covers and the blisters seem to have gone away.
Based on responses to me when I discovered this issue years ago, and the other comments in this thread, this condition does seem reasonably common, it does seem to be a cosmetic issue and I'm not convinced it matters.

[TolCarMan]

This might be a dumb question, but why do you care? The blisters are likely out of sight 99% of the time and they aren't affecting performance. I've never noticed them on any of my boats (I exclusively trailer), and even if I did I'm not sure it would be worth the coin to get them fixed knowing they could come back. I'd try to forget about them and go have some fun.

*I realize I'm probably in the minority lol

[JohnE]

Here is an old thread with a lot of good info. https://teamtalk.mastercraft.com/for...=20133&page=11

It's not "the carpet", it's "the water".

It does seem fairly rare from all that I've read here over the years. But it doesn't seem surprising. If it happened to me, I'd be pretty upset. But I would say I would have had fair warning.

[bturner2]

If we're going to go back to "it's the carpet" again and the carpet is causing a $200K boat to blister after only 2 years (which BTW I don't buy for a second) due to no fault of the manufacture's layup or materials then it would seem obvious to me that the trailer manufactures need to start using a different bunk material or method to support the boat (anyone remember EZ-Loader trailers with their roller setup?). The idea that someone can drop that kind of cash and there be no recourse when their Gel Coat starts to de-laminate (because that's actually what's occurring when a blister forms) after only 2 or 3 years even when the manufacture states a lifetime warranty on the hull seems ridiculous to me. Based on some of the hull warranties stories I've heard over the years there's really much they actually cover. If this was the response I got I'd fix the boat and buy another brand on principle alone.

As to just not seeing the blisters.... For years I had my boat on Shorestations with carpeted bunks and trailers with carpeted bunks. Since the bunks were in different locations between the Shorestation and the trailer I would have seen blisters either while on the lift or when I did the annual bottom waxing but never did. Based on what the OP is being told I'm a very lucky guy since this is apparently so common.

[gwozhog]

Out of 100k boats your two are antidotical at best. You could say, it's common for you but not the lot.

I would bet many boat owners have them but have never lifted their boats off the trailer on land so they are not aware of them. My current boat I felt them for the first time when I had a ski rope stuck on a skeg and I dove under the boat to free it up. Also if a boat has sat in hot storage unit for a few weeks the gellcoat blisters disappear until you get the boat wet again. So they could very well go unnoticed for most owners

[waterlogged882]

Compete and total bull$hit!!

It is not common for boat gel coat to blister!! Moreover, even more bull$hit for it to happen because of dry bunks. Who at MC came of with that crap? It's damn near the dumbest thing I've heard on these forums and some one at MC corporate office should put a stop to that crap.

Own it!!

Agree.

[CantRepeat]

If its not common how come my last 2 Mastercrafts have had blisters on the hull where it rests on the bunks? I think it has something to do with the way the boat is used. I trailer to and from my river over a 100 times a year. I also ride year round so my bunks are never completely dry.

Out of 100k boats your two are antidotical at best. You could say, it's common for you but not the lot.

[WhiskeyTango]

Blisters occur from extended water contact, in this case probably from wet bunks. The polyester gelcoat is inherently porous and eventually water gets through where it reacts with the laminate layers, pulling in more water by osmosis and eventually reducing the strength of the laminate. But that takes a long time.

I read somewhere that it happens faster on thinner gelcoat, but don’t know that for sure.

To the OP… My 2 cents would be that you check it annually and if the blisters appear to be getting worse, have it repaired.

I’d bet many of us have blisters above the bunks…

If you have it repaired, a vinyl ester primer barrier coat under the gelcoat may help prevent recurrence.

By the way, repair is a BIG job. Done right, it requires removal of the gelcoat in those areas and possibly some work on the fiberglass laminate.

[gwozhog]

Compete and total bull$hit!!

It is not common for boat gel coat to blister!! Moreover, even more bull$hit for it to happen because of dry bunks. Who at MC came of with that crap? It's damn near the dumbest thing I've heard on these forums and some one at MC corporate office should put a stop to that crap.

Own it!!

How many hundreds of thousands or even millions of gelcoat fiberglass boats out there that never blister? Common? You mean rarely does it happen and more then likely it's catalyst issue if anything.

Want to destroy brand loyalty? This is how you start it.

If its not common how come my last 2 Mastercrafts have had blisters on the hull where it rests on the bunks? I think it has something to do with the way the boat is used. I trailer to and from my river over a 100 times a year. I also ride year round so my bunks are never completely dry.

[CantRepeat]

Spoke with HQ. They are aware of this issue and say its common on boats that frequently use a trailer because of the friction on the dry carpets. There is no fix and since the Gel Coat warranty is only 1 year it would not be applicable since the boat is a 2015. So much for trying to keep the bottom unpainted.

Compete and total bull$hit!!

It is not common for boat gel coat to blister!! Moreover, even more bull$hit for it to happen because of dry bunks. Who at MC came of with that crap? It's damn near the dumbest thing I've heard on these forums and some one at MC corporate office should put a stop to that crap.

Own it!!

How many hundreds of thousands or even millions of gelcoat fiberglass boats out there that never blister? Common? You mean rarely does it happen and more then likely it's catalyst issue if anything.

Want to destroy brand loyalty? This is how you start it.

[bturner2]

IDK if I buy what they're selling. If it's the carpet scratching the Gel Coat then why use carpet on those trailers for those $150K boats? Or at least tell customers when they buy a boat that it's common for the boat to develop blisters with the carpeted trailer bunks they're selling you. If the carpet is the culprit then use Gator Bunks or some other material. I mean Come On Brandon, why wouldn't use Gator Bunks for an extra grand a trailer? More likely culprit is the materials in the layup not being just right. If not why do some boats do it and other not? I've seem plenty of boats over the years that were left in the water that had extensive blisters. Did the carpet do that as well? I've also owned quite a few boats over the years that were only trailered and (knock on wood), none that I've owned have ever developed blisters. Did I have magic carpet or something?

My understanding of blisters is it's caused by moisture getting between the gel coat and the fiberglass which would make sense that the areas under your bunks are where your blisters are. Some gel coats are better than others at preventing water intrusion but as with anything, everything can vary in the quality of materials and application. This is why I believe you see some boats prone to blisters and others well, not so much. Since my boats sit on a lift most of their life I switched to poly bunks at the recommendation of my dealer for this reason and because I never wanted to recover another set of lift bunks again. If I were trailering I would most likely go to Gator Bunks.

[gwozhog]

I was cleaning the hull for water stains before winter this year and jacked the boat off the bunks to find hull blisters where the hull sits on the trailer bunks. Dealer wants no part of helping. Just sent me hull warranty lingo.
I dry sail the boat from my trailer most of the summer other than a 2 week period it was in a slip this summer. It’s clearly an issue with with hull and factory trailer set up. Otherwise there would be blisters in other areas.
I have read others have had similar issues. Any recommendations on how to deal with this is appreciated.

Wasting your time and money worrying about it. Blisters are only cosmetic and since you have to jack the boat to see them they are pretty much out of sight out of mind. Go ski

[JohnE]

Common may be a stretch but it happens enough where they know about it and there is no fix. It was mentioned that I should expect it to happen again if I were to fix the blisters. The opinion was that the carpets are not given enough time when launching to lubricate so it scratches the hull. Moral of the story, find a ramp that is steep so you do not have to worry about the carpet abrasions and moisture wicking into the gel coat.

I've always heard it recommended to dunk the bunks completely prior to launching. I know some people that treat the bunks with liquid spray wax to help the boat slide off. I guess the dry bunks could also scuff the gel on a dry hull to compromise the gel and facilitate the blistering. DO NOT use silicone on the bunks, as that can lead to the bunks being too slick. I've heard a story or two of someone losing a boat off the back after treating with silicone.

[MCX46]

Common may be a stretch but it happens enough where they know about it and there is no fix. It was mentioned that I should expect it to happen again if I were to fix the blisters. The opinion was that the carpets are not given enough time when launching to lubricate so it scratches the hull. Moral of the story, find a ramp that is steep so you do not have to worry about the carpet abrasions and moisture wicking into the gel coat.

[JohnE]

I've heard of this happening on boats that are trailered numerous times. The water trapped under the hull and on the bunk carpet causes the osmotic blistering. With that said, I've always trailered my boats, some of which I put well over 100 hours a year on, and it's never happened. And it's typically not covered under hull warranty, from what I've read over the years. I wouldn't call it common, but I also wouldn't call it surprising.