deck and interior respray poly, epoxy or 2 pack paint?

[DHV90]

Hi everyone, yet another paint question but would really appreciate some guidance

I will be pulling the boat out in a few months to do a comprehensive resto and want to recoat the deck and most interior surfaces to get the boat looking like new again. I am aiming for a smooth and maintenance free(ish) finish which is tough and hard wearing, which can also take an extra coat (for non slip on the decks).

This will be applied to bare fibreglass on the interior, so I would like to add micro ballons or some sort of filler to the coating to smooth out the finish (ideally, but not essential) then on the deck I will be sanding back through layers of paint, down to original textured gelcoat (polyester I assume) and ideally spraying on to this rather than taking all the deck back down to fibreglass.

I currently like the idea of gelcoat, keeping an original looking, thick finish that can be buffed and polished, but after extensive reading am a bit confused with the limitations and terminology of gel coats.

Firstly, am I right that gel coat is either polyester or epoxy 2 pack coating with tint added? and that epoxy will go over poly, but not the other way around?


What would be recommended for a sprayed finish in this situation, ideally using the same process inside and out? The deck will have hundreds of holes filled and damages repaired so needs a good waterproof sealing finish.

Current idea is to sand back, fill and fair (on the deck), then build up thin layers of epoxy gelcoat before a flowcoat layer on the top, and then sand areas down for non-slip and apply awlgrip or something similar. I know this will take a lot of patience and prep work etc. so not afraid of that. Are any 2 pack paints like polyurethane about that offer serious advantages over gelcoat? should I be worried about the UV longevity of the gel? Do i need to seal after the final layer or do anything else to stop the gel getting chalky?

Or alternatively, sand fill and fair, layer up some high build epoxy primer, and then use something like awlgrip over the top?

everything ive read seems to be very divided making it hard to work out what might work better.

thanks in advance! (sorry for the hundreds of questions!)

 

[PaulRainbow]

I currently like the idea of gelcoat, keeping an original looking, thick finish that can be buffed and polished, but after extensive reading am a bit confused with the limitations and terminology of gel coats.

Firstly, am I right that gel coat is either polyester or epoxy 2 pack coating with tint added? and that epoxy will go over poly, but not the other way around?

Gelcoat is traditionally polyester and is applied as the first coat/s when laying up in a mold. It needs air to be excluded to fully cure. When using it over existing surfaces it will not cure unless the air is excluded. This can be done by covering it, but (IMO) the best solution is to add was to the gelcoat. This can be purchased in a styrene solution and added to gelcoat, or it can be purchased ready mixed, this is then referred to as flowcoat.

Gelcoat can be purchased in a variety of shades and colours and can be tinted by using pigments. Polyester gelcoat will adhere to properly prepared, existing/cured, polyester and epoxy surfaces.

Current idea is to sand back, fill and fair (on the deck), then build up thin layers of epoxy gelcoat before a flowcoat layer on the top, and then sand areas down for non-slip and apply awlgrip or something similar.

Nothing wrong with that, but don't try to do thin layers and not too many. Use gelcoat for the all but the final coat, as you say, the just add wax in styrene to the final coat.

should I be worried about the UV longevity of the gel? Do i need to seal after the final layer or do anything else to stop the gel getting chalky?

No need to wory about UV unless you plan to keep the boat for more than a few decades. Nothing you can add to stop it going dull over time, but regular polishing with a decent UV resistant wax will keep it looking good.

If you want to see what decades old gelcoat looks like just walk around any marina and look at the multitude of 70's/80's boats.

 

[DHV90]

Thanks for that very informative reply Paul, lots of useful info there and agrees with a lot of what I thought already, as you said all the boats sporting gelcoat of 30 or more years look great when looked after! Painted boats often look painted, whereas a factory fresh look is what Id like, even if it takes weeks of learning and effort!

I am hoping to own the boat for a long time, possibly a few decades, but if I can manage to learn how to do this this time round, Id rather be re-doing this once in 15-20 years, than repainting every 5!

Also, the health issues with 2k paint are a real issue, i'd rather not have to invest in a second filtered, remote compressor to keep me fed with clean air! Let alone protecting everyone else in the tightly packed boat yard from the fumes. Are there any health hazards with spraying gelcoat and epoxy primers? aside from a simple body suit and 3m mask? No fancy equipment required other than common sense stuff.


Current (first revision) plan is looking as follows:
sand fill and fair,
build up some high build epoxy primer and sand, clean, degrease etc.
Polyester gel coat
Poly flow coat
clean/abrade
non slip

Thanks again for your help though, Paul, theres so much info out there it gets a bit confusing, you've simplified matters a great deal already! Learning lots, looking forwards to getting started in spring

 

[Tranona]

You are letting yourself in for an enormous amount of work particularly if it is a reasonable sized boat with lots of fittings. Getting a good finish of the type you describe is very difficult, particularly if you are working out of doors. You need to strip down to the bare mouldings - not too bad for a hull (although Robert Wilson who posts here reckons he has spent 120 hours on his 30' hull to get it ready to paint), but decks and coachroofs are a mightmare to both prepare and paint.

Suggest you buy yourself a copy of the PBO publication describing what they did with their little Snapdragon - much the same as you are planning. Not only will you get good advice on what is involved, but you will then appreciate the enormity of the task.

 

[DHV90]

Got a reasonable idea of how serious the task is already, thanks, ive been reading up on this for almost 3 years and now finally in a position to research the more detailed aspects and put a plan together.

All deck fittings and interior fittings have to come off anyway and get replaced so thats a big portion of the work already happening. Its a big job, but the boat is worth it and it makes sense with our long term goals. Never plan on upgrading.

 

[PaulRainbow]

I am hoping to own the boat for a long time, possibly a few decades, but if I can manage to learn how to do this this time round, Id rather be re-doing this once in 15-20 years, than repainting every 5!

My gelcoat is 35 years old, i' not planning on replacing it anytime soon.

Also, the health issues with 2k paint are a real issue, i'd rather not have to invest in a second filtered, remote compressor to keep me fed with clean air! Let alone protecting everyone else in the tightly packed boat yard from the fumes. Are there any health hazards with spraying gelcoat and epoxy primers? aside from a simple body suit and 3m mask? No fancy equipment required other than common sense stuff.

Gelcoat isn't as poisonous as some 2K paints.

Current (first revision) plan is looking as follows:
sand fill and fair,
build up some high build epoxy primer and sand, clean, degrease etc.
Polyester gel coat
Poly flow coat
clean/abrade
non slip

I'd be inclined to skip the epoxy primer stage. If the surface is properly repaired it's necessary, infact, i'd say it was undesirable.

 

[DHV90]

Mind me asking why the epoxy primer would be undesirable? main reason for that was to cover the fibreglass weave on the interior surfaces with high build or microbaloons, but if unecessary its one less substance to be buying! Also thought it might help with general sealing of all the numerous holes on deck (they will be filled with poly resin first though)

 

[PaulRainbow]

Mind me asking why the epoxy primer would be undesirable? main reason for that was to cover the fibreglass weave on the interior surfaces with high build or microbaloons, but if unecessary its one less substance to be buying! Also thought it might help with general sealing of all the numerous holes on deck (they will be filled with poly resin first though)

Gelcoat is designed to be in contact with the GRP, so no need to isolate it from it. It will bond to properly prepared GRP perfectly OK. The epoxy primer would serve no purpose and will not adhere to the GRP any better than gelcoat and the gelcoat will not adhere to the primer any better than it will adhere to the GRP.

Gelcoat is high build. You will not be able to spray on a finish that will be "as new". It will need to be sanded and polished after it has fully cured. You obviously need to apply enough to allow for this.

Redundant holes in the deck would be best filled with proper filler, rather than resin, unless they are very small. Drill through the holes using a slightly larger drill bit than the hole diameter to make sure it's nice and clean before filling. If they are more than a few mm in diameter, taper them slightly.

 

[Tammany]

Been prepping mine for repaint for 6 months now although that has included some GRP work here & their. It does take a lot of time, way more than I had anticipated. Mine is going to be pure epoxy primer & 2 pack polyurethane though but prep is the same no matter what. It had a poorly done single coat system on it that I had to strip back. Best stuff I found for this was screwfix's own brand paint stripper. Few little jobs to finish then she's ready for her first coating.