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Is this paint or gelcoat?

3K views 8 replies 5 participants last post by  tommays 
#1 · (Edited)
So, this is my first boat, and today I began the process of trying to get the hull stripped down to the gelcoat in preparation for barrier coating and antifouling paint. Starting with the rudder, I scraped off all the old blue bottom paint that I could, but was still left with a light blue surface when I got it all off. I then industriously set to work sanding off the rest of blue until one side of the rudder was nice and white. Upon taking a closer look at the other (still blue) side, however, it seems quite smooth and not much like the consistency of the bottom paint I was able to scrape off.

So now I'm wondering--is it possible that the lighter blue is actually the gelcoat and that I just sanded half of it off one side of my rudder? Is there such a thing as blue gelcoat??

Photos attached. (Left side of the rudder had some delamination and was just ground down in preparation for reglassing the area...)
 

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#2 ·
The white is most likely gelcoat. Gelcoat can come in any number of colors like the red strip in the photos. But doing the bottom on a production boat is an extra step that no production builder will use because it serves no purpose. To be 100% positive, I'd have to get close. But if you'd sanded through the gel coat, that would mean that you're into the structural materials and that would mean that you'd see roving or mat.

Most likely, the light blue is a different brand or type of paint.
 
#3 ·
As far as I know, you only want to get down to the gelcoat if you have one of two conditions :

1) The bottom paint is losing adhesion so you want to take the whole bottom down to the gelcoat and repaint.

2) You have blisters and need to treat them and apply a barrier coat.

If neither is the case you just need to get down to sound paint, fair it, (sounds like the blue paint is pretty sound!) and apply new anti-fouling.

Sanding down to the gelcoat with a power sander on a hull that's blister free is asking to GET blisters. Chemical stripping is much kinder. No stripping is even kinder.

What is the reason you want to strip it?
 
#4 ·
The top layer of blue paint is quite brittle and comes off very easily, but you're correct, the lighter blue layer (whatever it is) seems very sound. My thought was to put on a barrier coat just for some extra insurance since it seemed like it was going to be very easy to strip given the age of the top layer, but perhaps this is overkill considering the overall condition of the hull. I'm definitely ok with not going to the extra trouble and expense if I don't need to....
 
#6 ·
If you don't have blisters and the light blue layer is really well adhered that's how I'd proceed - take it down to the light blue, fair it, and put on new bottom paint. Job done - for 3 years anyway ;)

I'd be weighing the damage sanding could do to the gelcoat, against the extra protection of the barrier coat. I'd actually say that not sanding to the gelcoat is the safer route.
 
#8 ·
There is just no downside to getting the bottom in good shape NOW :) while your on the hard

It is a PITA job BUT then your in for a pretty easy ride for a good long time
What's the definition of "in good shape?" Mine would be blister free, fair, and with sound, well-adhered bottom paint. He can get there without sanding down to the gelcoat.

There is a potential downside to sanding, which is thinning the gelcoat and even going through it in spots.
 
#9 ·
There is a potential downside to sanding, which is thinning the gelcoat and even going through it in spots.

Now that would not really be doing the a good job it would just be careless :)



We all see things differently but i see a hodge podge of peeling flaky bottom paint
 
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