Bottom Paint

[Roy10289]

I have purchased a hunter 37.5 that has multiple coats of bottom paint that is peeling off in many places. I would appreciate any advice on products or procedures to fix this problem. The surveyer said to sand lightly and just paint over again. Someone said that to sandblast all pait off would damage the gel coat.I have seen liquid products that you paint on and let set to disolve the old paint and then scrape off. Will such products damage the gel coat? I guess sanding is always an option however to remove a lot of old pait,is it difficult not to dig into the gel coat at the same time?Any insite or advice from personal experiences would be most welcome.

 

[Jim]

surveyer is right

Get a good multi-year ablative paint. Light sand with a drywall sponge. You just want to get the crude off. Don't scrath up the gel coat. One coat and you are good to go. You can just touch the paint up the following year. Heck you are in fresh water. You can get 5 years off of one coat.DO NOT USE VC-17! It is not a multi-year paint! I hope you don't have VC-17 on there now. It doesn't stick well and other paints don't stick to it. If you do have VC-17 on it, good luck!Bottom paint doesn't stick well because they don't get all the hull mold wax off before they paint the boat.

 

[Buck2796]

Roy

Google "Soda Blasting". Then call around to the local boatyards near Burlington to inquire who might be able to soda blast the bottom of your boat.It's a little more expensive than sand blasting, but kinder and less abrasive to your hull.

 

[Don S/V ILLusion]

flaking paint

the problem is if you don't cure the problem, it will continue to flake. The easiest way is to CAREFULLY scrape the old paint until you get to where is has adhered well at which point thoroughly cleaning and lightly sanding as your surveyor recommended will allow good adhesion of the new paint.Because of your location, we infer it is fresh water bottom paint, usually VC17 which is the most popular for fresh water. It looses it's efficacy once dried out so needs to be renewed every year. The downside is VC17 is not compatible with some other paints so you need to ensure you use the proper paint.sand blasting can do damage to the gelcoat as well as the environment so you have two reasons to avoid it. There are chemical strippers for marine applications which won't harm the gelcoat but they take time and lots of effort which may not be necessary unless your entire hull needs stripping.

 

[Jim]

I don't like the idea of scraping the bottom...

lots of people do it but I would prefer a chemical stipper. I would try a light sanding and repaint before you start removing the old paint! The paint will pop off when you roll the new paint on. Just wipe of the flakes with a rag and repaint.

 

[Rich (P303)]

First...

You need to figure out what is on there now if you are going to go over. See Interlux web site for this. They have some good info. If paint chaulks off on your hand when you give it a once over with your hand... it is probably an ablative. If it doesn't... it is a hard paint. Many paints are not compatable to go over others.If you are the keeping existing bottom paint on. I suggest getting a pressure washer and have at it. If it has many layers... I am sure you will get a lot to flake off. Sand existing bottom paint to rough up surface some... and repaint. No need to strip the bottom paint off or completely down to the gel coat and put on a barrier coat unless you are a round the bouys racer (and looking for that extra 1/2 knot) or plan on keeping your Hunter for a while. If you plan to stip... make sure the stripper is for Marine use and made for gel coat. It is a nasty job.You can spend an easy $4,000 for a bottom job. For the $4,000 you put into it... you won't get a dime more out of it if you plan to sell.Put it in the water and sail.

 

[Jim]

rpierpo1 has a good idea

preasure wash the boat first!

 

[steve rainey]

In this instance recently buying the boat and its flaking I would sand or use the home depot liquid remover and take it all off. Won't hurt the gel coat. The reason being if you don't, what is left and you paint over will fail and you'll be flaking again. When I first bought mine I put on 3 coats and was feeling like I really did a good thing. I regretted it for 4 years. The name of this game is one coat. Abative type, pull once a year and pressure wash, which will take most if not all of the remaining off and paint again. In my case in FL I pull it out every 6 months. summer for just a pressure wash, winter prep and paint and new zinc.

 

[Richard McDonald]

What I recently did ...

I purchased my 1979 Hunter H37C about 5 years ago, same situation, multiple coats, flaking paint. As many told me to do, I just sanded down trying to find solid paint and used ablative paint for 4 years.The problem was that every year, at haul out, when they pressure washed the hull, I would see my last coat of ablative paint being "cleaned" off the hull with more flakes, so here we went again with one more coat of ablative before the following launch. Obviously they must have being an incompatibility in the paint system (layers) over the years, prior to purchasing the boat.Last spring after looking at all of the nice clean hulls in the yard from my "racing" neighbors and a few discussions, I decided to take care of the situation.I had the hull blasted with corn husk, not as hard as sand or soda. After blasting, I was lucking to find a remaining thin layer of gray barrier coat, with no blisters, which I sanded with 80 grit and then applied 2 coats of Interlux InterProtect 2000E barrier coat and 3 coats of VC17m.I am cruiser, not a racer, but I can honestly tell you that in light wind condition, I gain 1 knot of additional speed and can now max out hull speed in much lighter wind conditions then before. Obviously the old peeling surface was creating a lot of drag and on crossings of lake Michigan, 1 knot makes a big difference. ( 1 knot over 12 hours of sailing is 12 nautical miles, that makes a 12 hour crossing almost 14 hours).So everything depends on the type of sailing you do and how long you plan to keep the boat. I was looking at a few Hunter 37.5 before I was lucky enough to find Rhapsodie our Hunter H37C. Your hull length is probably very similar to mine. I needed 6 cans of VC17m for the 3 coats. Rhapsodie was pulled this morning and after the power-wash (a light coating of green slime), I found a nice clean hull. I will apply one more coat of VC17m in the spring just before launching, no sanding needed. For our conditions and many up here in the great lakes (fresh water and pulled out every winter), VC17m is the way to go.