I have blisters in the clear coat from the water line down. I was not informed when I purchased the boat that you could not leave a custom painted boat in the water for more than a week. The damage is being warranted, but I am still a little confused about the whole issue. Are you telling me that any boat that has been custom painted and clearcoated cannot be left in the water for fear of blistering? Any answers would be appreciated.

pretty much... if there is an "edge" on the paint or clearcoat, water will eventually work its way in.....

WOW I never knew that. I never heard that or even read that

Clear coats used for this application fall into a group called aliphatic acrylic polyurethane. These work very well as a UV blocker and absorber and also have very good general chemical resitance properties. These same "paints" also absorb water even in the cured state. The water has mass and therefore when absorbed into the coating the coating expands in all directions including left and right - the increased tension causes delamination. This is more likely to happen on a base coat clear coat system becuase the base coat does not have strong physical properties however it will happen even with a single stage product. The failure rate is more likely to happen faster at higher tempratures.

Not too many ways around this problem. Aliphatic arylics @ 70 degrees will probably survive 10 days -2 weeks wet. Aliphatic polyesters will probably last 2-4 weeks. Moisture cured aliphatics will probably last 4-6 weeks. None of these are recomended for immersion service however.

* Clear epoxy will work on the underside, however epoxy will chaulk very quickly when exposed to direct sunlight

Amazing. With all the technology, you think they would have a clearcoat product that could withstand being in direct contact with water without blistering.

What do they use on drives?

Tri-Paint System (Irridite, EDP & Powder Paint) creates a tough, durable corrosion resistant barrier.

quote taken off merc's site...

Some boats like Cig'sCafe Racers have an infamous area on the bow at the base of the cowling that puddles water with no drains. If left for a couple weeks in the dead heat of the season the paint will sheet right off the surface.

Going through the samething with the clear coming off below the waterline.Not happy that will have to clear it every year if i leave in the water for more than a week i guess.The most i ever left my boat in the water was 7 days.

Clear coats are more of a problem than color coats - Formulators can put more "stuff" especially "sticky stuff" in paints with colors because it is masked by the pigment. Clear coats are very limited on what fillers and addatives can be put in them because of course they are "clear". While a condition may be present where you have an aliphatic acrylic polyurethane clear and an aliphatic acrylic polyurethane color, the bet will be that the "color coat" will hold up longer in a submerged condition. If you have to repaint the wetted portion of your hull do it with a color rather than a clear.

In the industrial world a aliphatic polyester polyurethane will hold up longer in a wet condition however it is still not recomended for continuous wetted service -

The fact is that there is just not a lot of demand for paints that are not epoxy and are often submerged. Even in the boat world a small percentage paint the hull with polyurethane.