Painting fiberglass boat, prepping questions

[PROS]

Hi,

Decided to paint top half of my Caribbean, aiming for epoxy high fill primer and 2pack polyurethane top coat.
Removed all bits and pieces except a stubborn rusted nut holding the right side of the hardtop down.

Sanded most of the starboard side down with 180 & 240 grid.
Ready to fill up the holes.

I have an area in question with hairline cracks that I cant figure out how to prep. Below are the pics
103820103821
There was U shape grab handle there before, I think the boat was previously owned by a diver and used the handle to get into the boat. The flex possibly caused the cracks on the gelcoat.
Dont think there is any issue with fiberglass underneath.

- Can I go straight over these cracks with primer & paint? I am assuming they will still be visible or will crack back up in no time.
- Should I groove and widen the cracks individually with a dremmel tool and fill up? Bit concerned that they will crack back up again if just fill up.
- Should I send the area completely all the way down to fiberglass and fill back up?


Second area in concern is one of the holes for the stainless railing at the front, pic below
Rectangle shaded area is covered with the railing attachment point, slight bit of crack is showing outside.
I am assuming widening the crack and filling is sufficient?
103822

Many thanks for your help.

Max

[shaungonemad]

I know with car panels these sorts of things come back out after awhile if not done correctly, I would think you will need to fill it with resin not just a filler but I am not an expert with glass. It will look good when done keep up the good work.

[Casey Ison]

Giday mate I had this on my cruisecraft in a couple spots before painting. I used a dremmel and grooved the cracks completely out and filled with fibreglass filler.. I did it 3 years ago and there is no signs of these cracks returning.. I made sure to groove the crack completely out to glass not just widen it.

Mine was not as bad as yours but I would possibly suggest sanding it back in the bigger areas and reshaping it with fibreglass filler then fine filler to finish it off.

That one with the front rail I would possibly suggest to put better support under it when you rebolt it down to try stop flexing and the gelcoat cracking further.

Once again im not an expert so im sure some others can explain further but it worked for me.

Cheers mate.

[PROS]

Crack lines in the area fairly close to each other.
By the time I groove each crack hardly anything ill be left in between so I am thinking the best approach is to sand the whole area down to fiberglass and fill it back up.

I bought a can of Gelcoat Putty to fill up the holes, suggested by the chandlery.
Would it be the correct product to use on the large area to be sanded as well?

[Casey Ison]

when I fixed up any holes I grinded the hole out and layed glass matting and resin until I built it up close to finished height and skimmed with bog or gelcoat putty as you have bought.. prevents a little crack around the hole once painted and a lot stronger.

[Casey Ison]

103842

heres a pic of the boat straight off the gun when I finished it.

[PROS]

Thanks Casey, looking great.

Did you remove the gunnel rubber during painting?

I am only painting up from rubber, wondering if I can get away with masking it?

[Casey Ison]

I put new gunnel rubber around it mate but yeah you will get around with taping it nicely.

cheers