I have a 17' fiberglass sailboat from the 60s. I'd like to sand/primer/paint the bottom. I have 2 paint colors with a line of tape splitting them near the water line. But as you go to the stern, that tape boundary runs well underwater. My question is - should I just use bottom paint for the entire hull up to the gunwale? Or just for the bottom half, and use topside paint for the top half where it's currently white?
Bottom paint question
- Thread starter barney17
- Start date
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,553
with @Project_Mayhem.Before you start to paint, make sure the tape on the starboard side mimics the tape on the port side. You want the paint lines to be symmetrical. Otherwise you might tip over...
The image appears to show that when the boat is in the water, it floats high on the surface. Some boats do this, and others do not. If in doubt, splash the boat and check that the lines are where you want them. There should be no problem with putting the boat in the water. It will dry out in a day after you put it back on the trailer. You will be certain about the water line.
Definitely don’t use bottom paint for the topsides (above the waterline). Bottom paint is not designed to look good, especially out of the water. The boot stripe - the blue stripe above the waterline - may be gelcoat and not paint now. If it is gelcoat you could compound, polish, and wax everything from the boot stripe up to restore their color. This thread has everything you’d need to know for that process - Tips For A Great Buff & Wax. For below the waterline before painting check the adhesion of what’s already there. From the looks of one of your pictures there may already be quite a few layers of paint. Over times those layers become susceptible to flaking off, especially when you roll new paint on.
It is not unusual for the static waterline, i.e., the waterline when the boat is in still water and not moving, is below the curve of the hull in the aft quarter, mine is. If the boat is heavily laden then hard growth, barnacles and such, may grow above the water line, soft growth will almost always be at and slightly above the water line.
The only time to apply anti-fouling paint to a trailer sailer is if the boat will be left for months in the water. If the boat is trailered, every time the boat is launched and hauled a bunch of paint will end up on the trailer. When trailering just wash the hull with a high pressure wash and be done. A DIY carwash works.
The only time to apply anti-fouling paint to a trailer sailer is if the boat will be left for months in the water. If the boat is trailered, every time the boat is launched and hauled a bunch of paint will end up on the trailer. When trailering just wash the hull with a high pressure wash and be done. A DIY carwash works.
Ah thank you for all for the help. The boat does live on the trailer, so I understand the bottom paint isn't really needed.
I'm only thinking of painting because it's chipping a bit. So if I'm never keeping it in the water could I sand, prime, then put topside paint on the entire hull? Or still best to just put the bottom paint where I have it currently, then topside paint over the white?
I'm only thinking of painting because it's chipping a bit. So if I'm never keeping it in the water could I sand, prime, then put topside paint on the entire hull? Or still best to just put the bottom paint where I have it currently, then topside paint over the white?
I wouldn't do anything. Let the paint erode away and maybe someday sand the remaining off. Topside paint generally doesn't do well underwater even for relative short periods of time.
Interlux used to make an epoxy based paint that was the darling of the racing set. It could be sanded and polished smooth as glass, looked good and was fast. A paint like that would be good. I think i was called VC Performance Epoxy or something like that.
, but just note that if you’re going to apply a bottom paint like that (or most any type of paint) you’ll first need to remove all of the existing paint. Putting more paint over flaking paint won’t stop the flaking, it’ll just be hard to apply with flakes sticking to the roller. Also most high performance paints like that aren’t compatible with more traditional lower layers. Without knowing what kind of paint you currently have overcoating risks incompatibility driven lack of adhesion for many paints.
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,553
Do not put topside paint on the bottom. It will flake off. What doesn;t flake off is a very large job to remove. Trust me, I did that on my 19' sailboat. It took half a summer to get it off with sandpaper and paint stripper. If you're going to paint it with something other than bottom paint, I'd go with a two part paint, preferably epoxy based. The trailer is going to be tough on the paint. You want something that will hold up well or is easy to touch up. I think the easiest option would be hard bottom paint as opposed to soft ablative
jssailem
SBO Weather and Forecasting Forum Jim & John
- Oct 22, 2014
- 22,553
Your experiences with this challenge support the idea of a hard bottom paint. Many topside two-part paint companies suggest that boats that live on their trailers can succeed with their paints. I think it is dependent on how the boat is used. A short duration, 24-48 hours, on water, then up on the trailer, can work. If you are racing your boat, frequent painting for that super smooth surface is a normal practice.
All is dependent on how the boat is being handled and sailed. A hard bottom paint would be a reasonable option, especially if the bottom paint can be polished.
All is dependent on how the boat is being handled and sailed. A hard bottom paint would be a reasonable option, especially if the bottom paint can be polished.
This has been pretty well answered. I just want to add that having a contrasting paint below the waterline is not purely cosmetic on a trailered boat. It brings with it the advantage of having the area of the boat most subject to abrasion already clearly demarcated. So, it is easier to repaint/repair/touch up that area in the future without having to redo the entire hull.