Bottom Paint Advise

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Mike D

We have a 1998 Hunter 376. I have used nothing but Interlux Micron Multi year Ablative. Basically, about 4 coats of this paint have lasted for 9 years, only needing touch up during the off season. The problem revolves around the touch up. It seems that it is the same spots over and over that do not adhere. I intend to leave the boat in the water for an extended period. The thought of these spots peelin bothers me. When they peel I am looking at gelcoat. My guess is that the initial prep was not thorough in removing the mold release wax. Hunter strongly advises AGAINST sanding the gelcoat due to a "blister preventing" additive of sorts. How do I get something to stick to these areas. I have used the chemical recommended by Interlux with no luck. There does not seem to be a primer coat under the bottom paint. Is there a good quality primer that will help the paint adhere? How do I handle the areas that are not quite stuck and not quit loose, without sanding? Since I have been able to reuse the base coats for multi years, there is not a big build up of paint on the bottom. I would hate to remove it all wen less than 10% of the bottom is problematic. Any advise and experience is welcomed. Mike D
 
May 31, 2004
82
Gulfstar 37 Aft Cockpit New Orleans
It may be a dumb question, but....

Is there any pattern to where it doesn't seem to stick, such as at the leading edge of the keel or the rudder or other high velocity flow areas? It would be normal for an ablative paint to wear off quicker in these areas. Also, when removing wax prior to painting, the directions always seem to say use lots of clean cloths, wipe only one direction, so you don't just push the removed wax down into the pores of the gel coat...you need to remove wax even before light sanding to stop that from happening. I would think you need to take the ablative off down to the orginal gel coat surface, clean with lots of solvent and clean rags, lightly sand (600 grit?)just to give the surface a little tooth, clean again, and then I bet it will stick... just a couple of thoughts..
 
Feb 12, 2007
259
Ericson 25 Oshkosh, WI
Bottom Issues

Mike- I know nothing about Hunters anti-blistering additive. If you feel that your boats bottom was not properly prepped for bottom paint. Now its your time to do the job right, right. In your areas of issue, get all the paint off, wipe down with Interlux 216 to clean residue, hopefully the suspected wax. Do this first, so you dont sand the wax in. Get a 3M scotchbrite pad, the red one. Score up the affected area. Then wipe the surface again with 216. Re-apply your bottom paint. There is no reason to now need a primer. If you have wax, it will throw the primer. I have never owned a Hunter, but I would believe many of their boats have had their bottoms sanded with no issues of blistering. I personnaly would sand with 320 grit, but the scotchbrite is less agressive. Give Interlux a call to hear what they have to say. Best of Luck. Rob Hessenius
 
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Warren Milberg

On a previous boat...

...with something of the same problem (hard to know without seeing your boat), I cleaned the spots where the paint didn't adhere well with acetone, then used a very mild grit emory paper (i.e., 6oo grit or so) and then sprayed on Interlux Primocon, then applied the bottom paint when the Primocon dried. I never had the problem again. A far more labor intensive solution would be to remove all your old paint and then put on a barrier coat, then repaint....
 
Sep 25, 2008
7,687
Alden 50 Sarasota, Florida
Recent thread regarding sanding

Not sure where but you can find it in the archives. Discussion similar to this regarding prep for bottom painting included whether or not to sand. Someone talked to Hunter directly about sanding and quoted the factory as saying it is not a problem on older boats. Their concern, as I recall, was the potential for frivilous warranty claims resulting from improper or negligent sanding which obviously isn't a problem with a 98 boat. All the good suggestions before may work as effectively but it appears sanding is not, as the rumor goes, something Hunter frowns upon (presuming the poster was correct).
 

Mike D

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May 10, 2004
64
Hunter 376 Annapolis, MD
Bottom Paint Thanks

Thank you all for your concern and replies. I think that I have an adequate handle on the situation now to take on the project. I was concerned about damaging the integrity of the gelcoat, insofar as blistering. Without this concern I am good to go. Thanks again, Mike D
 
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