Repairing GRP topside - lots of small holes and imperfections!

[Eccles291]

Hi all,

I've just joined the forum as it looks like a great place to get lots of useful advice. We have a Seamaster 8M river cruiser that needs a lot of work! Aside from stripping out the whole of the interior (there had been a fair amount of water ingress) there's the outside to tackle too. There are a lot of old screw holes, chips, dings, bad repairs and general imperfections in the outer skin that need filling, mainly on the top of the rear cabin. (See photos, below).

What I'd like to know is: what's the best way of tackling it? I've not done this sort of thing on a boat before but I'm an ex-builder and we've previously converted a 7.5T lorry from a tired, old horse box into a 6-berth motorhome.
I've been searching for what I need and I think gelcoat filler might be the stuff I need? My only reservation is that almost the entire top of the rear cabin needs sorting so I wonder if it's best to plan on filling all the holes and then sand & paint the entire area? Recommendations for fillers, paints and anything else would be very welcome.

Thanks very much.

https://imgur.com/AcHrDmc

https://imgur.com/l5ZFLym

https://imgur.com/lYsY0KB

https://imgur.com/bUMHFVq

https://imgur.com/g2trFLl

 

[chris-s]

If it was me, I would clean up each hole using a dremel and then fill with either thickened epoxy or some white colored gelcoat filler (East Coast Fibreglass ?). You are unlikely to get a color match, so probably a coat of white Toplac afterwards to smarten it up. Easy peezy. If you wanted to try for the best color match, then before starting with the dremel, wash it with an Oxiallic based cleaner to remove the staining, then wetsand it all with 800/1000/1500 wet and dry to remove the oxidation. That will give you a good clean surface to try to get something approximating a similar color.

 

[Eccles291]

Thanks for the reply. I think a colour match will probably make even more work than there already is , so a coat of white definitely sounds like a better option. What's the coverage like on Toplac? Is it likely to need a few coats? Can you get a decent result with a roller?

 

[johnlilley]

Wondering if it would be more practical to aggressively sand the whole of the area back to clean gel coat & overlay with a thin layer of glass cloth & epoxy resin. Looks as if you could go up to the edges in most places which means a tidy finish. Much more reliable & adding a degree more of strength. Laminating over is quite an easy job really.. Of course, you would then have to cosmetically complete as normal, but relatively simple & much more reliable long term.

 

[Refueler]

Clean up ... fill holes etc with Gelcoat .... longboard sand to avoid creating uneven surface .... couple of coats of decent two pack paint ....

I certainly would not get into glass cloth and resin - hard work to get it smooth and even again ...

 

[Boathook]

I would clean the top and holes well, then use thickened epoxy resin for the holes. Then paint as epoxy doesn't like the sun unless special epoxy / additives used.

 

[Stemar]

Another vote for fill, smooth - Refueller's longboard is a good idea, but there's a reason they call it the torture board! - and paint.

As long as it's only small holes, I'd use a polyester filler - car stuff would be fine for that application, but I'd use a marine filler for the hull, as it's more likely to get wet and stay wet - there's special stuff for use on or below the waterline.

 

[V1701]

Countersinking holes above and below is a good idea, won't be necessary with all of them but some probably. Tape some greaseproof paper on the underside and fill with whatever you choose...

 

[William_H]

Yes tape over inside of through holes. Fill with thickened epoxy. Sand flat and paint. A caution for white colour. I did this with my little boat and now sun glasses are mandatory due to glare. Most new boats have a beige colour. Second problem is that the deck may have a non skid surface. If not great. if so then painting will smooth out the non skid. You may need to add grit to paint to get a grip. I used a commercial 2 pack polyester paint just brushed on. Not perfect but a vast improvement on the old surface.

 

[Refueler]

Yes tape over inside of through holes. Fill with thickened epoxy. Sand flat and paint. A caution for white colour. I did this with my little boat and now sun glasses are mandatory due to glare. Most new boats have a beige colour. Second problem is that the deck may have a non skid surface. If not great. if so then painting will smooth out the non skid. You may need to add grit to paint to get a grip. I used a commercial 2 pack polyester paint just brushed on. Not perfect but a vast improvement on the old surface.

Easy enough to fill / sand / paint as said ...

For Non Slip - I use household exterior wall paint .... its cheap - can be mixed to any shade / colour .... water based ... easy to sand off - easy to touch up ... and even in white - is non glare !

 

[Concerto]

You may find this presentation I gave to the Westerly Owners Association worth looking at on gel coat renovation.

https://wiki.westerly-owners.co.uk/images/8/86/Gel_coat_renovation_19May2020.pdf

 

[PCUK]

I'm with JohnLilley. Sand the whole lot back, mat or tissue and resin and then fair with epoxy filler. Prime with epoxy primer and then paint. You can use car aerosols if you want a professional looking gloss finish. If you just fill individual holes it will never look really good.

 

[Ian_Edwards]

The problem is now resolved. The local engineering company has source 4 of the original couplings, 3 days delivery.
Thanks for all the suggestions, but fitting replacement couplings is by far the easiest option.
As foot note, I find it amazing that you can get spare parts for a 50 year old engine, on 3days delivery, when I often struggle to source spares for my Yanmar.

 

[Refueler]

The problem is now resolved. The local engineering company has source 4 of the original couplings, 3 days delivery.
Thanks for all the suggestions, but fitting replacement couplings is by far the easiest option.
As foot note, I find it amazing that you can get spare parts for a 50 year old engine, on 3days delivery, when I often struggle to source spares for my Yanmar.

????? You on same subject or just misplaced your post ???

 

[Refueler]

I'm with JohnLilley. Sand the whole lot back, mat or tissue and resin and then fair with epoxy filler. Prime with epoxy primer and then paint. You can use car aerosols if you want a professional looking gloss finish. If you just fill individual holes it will never look really good.

Honest ... what a palaver when its easy to solve.....

Sand - fill - sand - paint ...

As a person who has glassed many an item - I can only say the work to then get a nice smooth level surface will be a lot of work ... You say epoxy filler ... by time you get it level - the differences in colour shades will be worse through whatever paint you use than just filling holes - sanding and then paint will be fine ...

Simple fill - sand and paint can be a days job and finish ...

Glassing - filling - levelling ?? then painting ??

 

[PCUK]

Depends if you're bothered about the finish or not. There's only one way to get a good looking finish and that's to do it properly. All depends on personal preference and there's no right or wrong way, just the way OP wants to go.

 

[Refueler]

Depends if you're bothered about the finish or not. There's only one way to get a good looking finish and that's to do it properly. All depends on personal preference and there's no right or wrong way, just the way OP wants to go.

To get it nice - is precisely why I would shy away from glassing it ...

Properly ??? Who decides what is 'properly' ??

 

[PaulRainbow]

Clean up ... fill holes etc with Gelcoat .... longboard sand to avoid creating uneven surface .... couple of coats of decent two pack paint ....

I was with you up to the paint. If it's filled with gelcoat and sanded, why not just compound the gelcoat ?

I certainly would not get into glass cloth and resin - hard work to get it smooth and even again ...

Agree with this 100%. Makes no sense at all to me to glass over minor holes and imperfections.

 

[Refueler]

I was with you up to the paint. If it's filled with gelcoat and sanded, why not just compound the gelcoat ?

[/QUOTE]

Often the gel doesn't match - so I would usually give a couple of coats of two pack paint to get a uniform finish.

Agree with this 100%. Makes no sense at all to me to glass over minor holes and imperfections.

Glassing .. seen too many decks / coachroofs spoiled by glassing - when simple fill and sand would have done the job much better.

 

[Eccles291]

Thanks for all the replies. I think, having read all the suggestions, going with filling, sanding and painting will probably be the order of the day. The entire boat needs repainting so to begin with I'll probably just fill the holes for now and then paint everything all at the same time. Time to order some gelcoat filler and get busy!