Filling over screws in GRP

[Trident]

My boat is being painted next spring as after 40 years the gelcoat is too thin to polish any more

Over winter I am busy repairing spider cracks and dings so it's a quicker job when the time comes.

My coach roof / centre deck (catamaran) is basically a big box mould screwed down on to the hulls over its full length . It has a stainless screw every 5 inches for 10m or so. These hold the central deck section on to the deck of the two hulls. It has never leaked and is in pretty good condition but its just a bit ugly with all the screw heads showing. The screws are countersunk so sit a little below the deck moulding level.

Obviously there is a corrosion issue when stainless is deprived of oxygen (though if completely deprived corrosion can't occur) so is there a filler product that I can fill and fair over the heads with before paint or is this just asking for future trouble (boat is 40 years old BTW) ?

 

[Boathook]

I have never had success with filling holes, especially where the screw or bolt head is just below the surface. I would just paint and if a future problem occurs at least you know where the screws are !

 

[johnalison]

I would not aim to make a cosmetic repair but possible cover with a soft, presumably white, filler leaving a slight dimple that wouldn’t catch my eye as much as the screws.

 

[rogerthebodger]

There are all kinds of plastic caps for exposed screw heads like those below

b&q screw cap covers - Bing

 

[Trident]

There are all kinds of plastic caps for exposed screw heads like those below

b&q screw cap covers - Bing

Yes but it’s on a deck so they’ll wash away or get kicked away as one walks or swallowed by the cat

 

[penberth3]

There are all kinds of plastic caps for exposed screw heads like those below

b&q screw cap covers - Bing

You haven't read the first post, have you? The bit about countersunk screws?

 

[rogerthebodger]

You haven't read the first post, have you? The bit about countersunk screws?

Yes, I did there are various types of caps for various screw head types.

The P started a shallow countersink, and I have used countersink types mainly inside and I note the OP was talking about outside on deck

 

[davidmh]

Are any screw heads just proud of the surface - if there are I would take that screw out and countersink it until it is flush. It would also be good time to check that all the screws are tight and none have stripped the thread after 40 years. the painter/sprayer and you will have to decide whether to paint the paint the screw heads or mask them.
David

 

[Davy_S]

I have used this stuff to repair lots of scratches and screw/bolt holes, difficult to get in small tubes, but it is easy to use and works well.

 

[Fantasie 19]

I have used this stuff to repair lots of scratches and screw/bolt holes, difficult to get in small tubes, but it is easy to use and works well.

..or Milliput Super Fine..

 

[PaulRainbow]

There are all kinds of plastic caps for exposed screw heads like those below

b&q screw cap covers - Bing

150 of those on deck will look terrible Roger, i'd rather see the screws than those.

 

[Trident]

I have used this stuff to repair lots of scratches and screw/bolt holes, difficult to get in small tubes, but it is easy to use and works well.

I've mixed a load of gelcoat (obsessively to the right colour even though it will be painted over) and got various additives to thicken depending on what I'm repairing as I'm doing all the star cracks, dings etc before it goes to paint to save time on the hard.