I have blisters - thousands of them

[Loala]

Some boats spend a lifetime with no bottom prep and never get blisters. Others get them when it rains. There is no reason for that but it's true.

I believe there is a reason, we just don't know what it is.

However, I suspect most people believe it is a Mfr. QC problem, which may be the case.

[James V]

That may be true but if the factory tells you to do something and you do not. If there is a problem in that area, Your fault. Per my understanding that is the way it works.

[DaveB]

Any Mac. that stays in the water more than 2 weeks needs 3 epoxy barrier coats. This will prevent mosture penetration, the Gel. Coat (Gelcoat absorbes water).
Layup at factory can produce air bubbles between gelcoat and glass and after a period in time cause a acid build up between the layers (air Bubbles) causeing delaminate.
Those with boats in water use 2-3 coats 2000 interlux barrier coating.
Those who Trailer Sail use Starbrite Marine polish with PTEF. (2 coats 10 days apart, 1 coat every 6 mo. after).
Bottom paint will not prevent osmosis, the epoxy coating will.
Dave



I believe there is a reason, we just don't know what it is.

However, I suspect most people believe it is a Mfr. QC problem, which may be the case.

[/quote]

[Loala]

Dave,

Is it all boats with gelcoat can get blisters, or only the ones with air bubbles between the gelcoat and glass?

[Dimitri-2000X-Tampa]

I dunno if I fully agree with that Dave. My 2000X has spent more than half its life in the salt water here in Western Florida, more than a year at a time for at least 2 times that I know of. There is no barrier coating and just some ablative bottom paint which has worn off in multiple locations before. In the spots where the paint wore off, I've had an awful case of barnacles requiring a lot of scraping, but never a single blister. I know blisters, my former keel boat had plenty of them, but my Mac has never had them even without the barrier. Seems like a lot more blister stories come out of freshwater.

[Oskar 26M]

There is a very informative article about osmosis here. It helps to explain why the risk of osmosis varies so much between individual boats, specific areas on the boat and between boat-builders.

As you might recall from science osmosis experiments using a cellophane membrane, it is the presence of soluble molecules that are too large to pass through the semi-permeable membrane that create a pressure gradient, attracting water molecules to their side of the membrane. With fibreglass his is more likely to occur in a poorly controlled construction process

To quote from the site:
Despite most people’s assumptions to the contrary, fibreglass mouldings, no matter what resins are used, are not actually totally waterproof. Individual water molecules are so small that they can actually find their way into and ultimately right through the layers of glass and resin forming a boat hull, or GRP pond liner. This in itself is not osmosis, it is simply a minute degree of permeability of the material.
The problems start to occur when the water molecules migrating into the GRP encounter other chemicals inside the laminate, primarily water-soluble materials (WSMs) such as the the emulsion binders used to hold the glass mat together before it is moulded, or pockets of uncured or only partly cured resins in the moulding. The water molecules can then have a chemical reaction with these substances, forming larger molecules of a new chemical, often acidic - which unlike the original small water molecules, cannot carry on passing through the GRP. These larger molecules are then trapped. This is the point at which osmosis actually starts.

My old keel boat had ongoing osmosis problems, but the most troublesome and worrying occurred where the aft end of the keel joined the hull. The dimensions of some of the blisters that developed there could be measured in inches. My guess is that there were numerous pockets of un-cured or partly cured resin in that location, as a result of poor mixing of chemicals during construction.

[James V]

Nothing, they will refer you to the factory and let you work it out. As far as anybody knows, the factory has never fixed any bad boats or paid back the dealiers for any cost fixing them. Shipping you a part, yes.

Inspect your boat when you get it before signing any papers. If you see something you do not like, skip it and Get the next boat or go to the factory and pick it up.

I regret that this is part of the cheep price that we all must deal with. Do not expect steak when buying 30% fat hamburger. There is more about this with the "X"'s. The "M" are better.

[Kelly Hanson East]

IN short, to my limited knowledge, no one has recovered repairs from the factory on any boat. The warranty does exlude this explicitly, so you can argue this point as much as you want. The option to the buyer is to look at the next level of boat, which is 2x in price, and will have the same issue of course.

[Derrick]

I just pulled my 2007 M (hull 1644) out of Lake Michigan last Sunday. It sits in the water from mid May to Mid October for the last two summers.

Before it ever went in the water last year I put two coats of Interlux barrier coat and anti fouling paint on. I left a 1.5 inch gap of white stripe between the botton coat / anti barrier and the black water line stripe.

As everyone knows, the M sits bow heavy. When I pulled the boat and scrubed the water line clean, I found blisters (very similar in texture than those posted) between the barrier /anti fouling coat and the original black water line marker on the bow only where it sits deeper in the water.

After further inspection on the hull where barrier coat has been applied, I do not see any issues with blisters.

I am very glad that I barrier coated, otherwise I may be a very PO'd Mac owner right now (not that I am happy with the blistering I have already).

I have not contacted my dealer yet, but I will.

I will probably let dry over the winter, sand the blisters out in the spring and apply barrier coat on the white stripe I left below original water line and apply anti fouling paint an the whole bottom again.

Hopefully that will solve my problem and the barrier coat will save me from further issues?

I would certainly recommend barrier coating and I often wonder why manufacturers just don't do this on their own on new boats. My dad had power boats for years and his last boat went back to the dealer 3 times to have the blisters removed and he never paid a dime for it and the manufacturuer covered all the costs. After it was fixed the last time he sold it.

[James V]

You really get what you pay for. The barrie coat will die very easly with sun. Bottom paint is also needed for different areas and different types. Your choice.

Most people do not keep their Mac in the water for more than a few days. In that case any bottom paint is not needed. Why should the factory charge them for it?

If you plan on more than 3 weeks in the water, put something on the bottom. Any boat.