Leaving resin/glass exposed over winter

[Matwill]

Hi,

I need to repaint the bottom of my boat - I did a test scrape and i can scrape all the way down to what looks like the clear resin so i can see the fibreglass matting underneath, I also needed to dry the boat out, do you think leaving the boat out without paint over winter will degrade the grp?

 

[coopec]

UV radiation would be a problem but only if you get sun so you could rule that out living in the Netherlands. Rain shouldn't be a problem on the hull as it would run off quite quickly. (I wouldn't leave it immersed in water though)

 

[Matwill]

yes i was more thinking about the UV

 

[PaulRainbow]

UV radiation would be a problem but only if you get sun so you could rule that out living in the Netherlands. Rain shouldn't be a problem on the hull as it would run off quite quickly. (I wouldn't leave it immersed in water though)

yes i was more thinking about the UV

Polyester based GRP is UV stable.

 

[coopec]

Polyester based GRP is UV stable.

Sorry Paul you are wrong. (BUT the exposure to UV radiation would have to be prolonged)

The Effects of Weathering on Mechanical Properties of Glass Fiber Reinforced Plastics (Grp) Materials
This work has revealed that the decrease in the mechanical properties of GRP under weathering conditions is subjected to atmosphere conditions such as humidity, temperature, ultraviolet radiation and pollution.

https://www.researchgate.net/public...Glass_Fiber_Reinforced_Plastics_Grp_Materials

 

[Lon nan Gruagach]

Sorry Paul you are wrong. (BUT the exposure to UV radiation would have to be prolonged)

The Effects of Weathering on Mechanical Properties of Glass Fiber Reinforced Plastics (Grp) Materials
This work has revealed that the decrease in the mechanical properties of GRP under weathering conditions is subjected to atmosphere conditions such as humidity, temperature, ultraviolet radiation and pollution.

https://www.researchgate.net/public...Glass_Fiber_Reinforced_Plastics_Grp_Materials

You should read the start of the paper presented on that page. The only reference to polyester is in the abstract. A very similar sentence at the start of the actual paper uses the word plastics, not polyester. Also the paper then explicitly refers to carbon fibre reinforced with epoxy matrix (not sure if they got that the right way round.....)

 

[coopec]

You should read the start of the paper presented on that page. The only reference to polyester is in the abstract. A very similar sentence at the start of the actual paper uses the word plastics, not polyester. Also the paper then explicitly refers to carbon fibre reinforced with epoxy matrix (not sure if they got that the right way round.....)

Whatever.......

 

[Stemar]

One winter will make no difference to the condition of the GRP. In fact exposing it and leaving the rain to wash it down may even have a small beneficial effect, by removing styrene and thereby drying the hull a little.

 

[PaulRainbow]

Sorry Paul you are wrong. (BUT the exposure to UV radiation would have to be prolonged)

I'm not wrong, i suggest you do some more Googling.

Try looking into translucent GRP roof panels, for instance.

 

[Matwill]

I believe the boat (made 77) uses isophthalic resin in the grp

 

[earlybird]

I had a boat built in 1970. The forehatch was partly plain GRP, ie not gelcoated, in order to let in some light. It was fine when I sold it in 2004.
Perhaps the gloss had worn off somewhat.

 

[coopec]

I'm not wrong, i suggest you do some more Googling.

Try looking into translucent GRP roof panels, for instance.

I don't need to do googling as Bruce Robert-Goodson (a yacht designer) warns of U/V degradation during construction: maybe you should set him straight!!

What is Gelcoat
Simply stated, gelcoat is the outermost structural layer on a fiberglass boat hull, designed to protect the underlying fiberglass layers. Gelcoat is a compound that produces a high-quality finish on fiberglass surfaces and incorporates a lot of chemistry, using epoxy, polyester resin, a catalyst, and other chemicals to achieve its strength and water-resistant properties. When cured, gelcoat combines with fiberglass to produce a smooth and durable surface that retards hull weakening from water intrusion and ultraviolet light.

 

[PaulRainbow]

I don't need to do googling as Bruce Robert-Goodson (a yacht designer) warns of U/V degradation during construction: maybe you should set him straight!!

What is Gelcoat
Simply stated, gelcoat is the outermost structural layer on a fiberglass boat hull, designed to protect the underlying fiberglass layers. Gelcoat is a compound that produces a high-quality finish on fiberglass surfaces and incorporates a lot of chemistry,using epoxy, polyester resin, a catalyst, and other chemicals to achieve its strength and water-resistant properties. When cured, gelcoat combines with fiberglass to produce a smooth and durable surface that retards hull weakening from water intrusion and ultraviolet light.

Your Googling isn't great, is it ?

You've just hunted around to find something which you think supports your flawed argument. Note my highlighting above, gelcoat does not contain epoxy and polyester, it's one or the other. It also doesn't "combine" with fibreglass, it's just an outer layer that's applied to the mould before the grp layup.

Try looking again, for polyester based GRP. Not epoxy (more usually used for carbon fibre, not boats), but polyester. Polyester GRP is UV stable, it''s used, without gelcoat, to make translucent roof panels. Also, see post #11

 

[coopec]

Paul

Obviously you would never admit you are wrong. Up to now I would get cross when OP were critical of your comments but not anymore. (That is sad because I always thought you were one of the experts)

You should stick to your area of expertise and don't express views on subjects you know nothing about.

Have a good day!!:encouragement:

Clive

NOTE
I have no idea why you have brought the composition of gelcoat into the argument but:
Gelcoat or 'Gel Coat' is a material used to provide a high-quality finish on the visible surface of a fibre-reinforced composite. The most common gelcoats are thermosetting polymers based on epoxy or unsaturated polyester resin chemistry. Gelcoats are modified resins which are applied to moulds in the liquid state.

 

[Lon nan Gruagach]

https://www.seabase.eu/category/marine-and-boatbuilding/polyester-resin/

 

[PaulRainbow]

Paul

Obviously you would never admit you are wrong. Up to now I would get cross when OP were critical of your comments but not anymore. (That is sad because I always thought you were one of the experts)

You should stick to your area of expertise and don't express views on subjects you know nothing about.

Back in the late 80's, early 90's i owned a small company that manufactured GRP products, so i possibly know something, although i wouldn't claim to be an expert.

Where does your knowledge of the subject come from ? Google it would seem.

NOTE

I have no idea why you have brought the composition of gelcoat into the argument but:
Gelcoat or 'Gel Coat' is a material used to provide a high-quality finish on the visible surface of a fibre-reinforced composite. The most common gelcoats are thermosetting polymers based on epoxy or unsaturated polyester resin chemistry. Gelcoats are modified resins which are applied to moulds in the liquid state.

Erm..... you was the one that brought Gelcoat up in post #12, don't you remember ? I simply pointed out flaws in the quote you had found. This latest one look more accurate, well done.

 

[Graham376]

I don't need to do googling as Bruce Robert-Goodson (a yacht designer) warns of U/V degradation during construction: maybe you should set him straight!!

Better known as Bruce Roberts, designer and seller of plans. When I spoke to him 20 odd years ago, he was still mainly pushing steel boat plans for cheap home construction (Sprays being maybe the best known) and fairly scathing about the strength of many plastic ones. Not that I'm saying he was biased

As Paul says, there are many clear uncoated polyester roofing products and it's usual practice with damp/osmotic boat hulls to strip the gel coat and leave outside to dry naturally in sunlight, particularly in hot climates (where there's plenty of UV) where forced drying isn't needed. The OP won't have any problems with a small exposed patch and he says it's on the bottom anyway.

 

[Marine Reflections]

OP:
I think you'll be fine to do that without any worries IMHO.

Coopec:
This is a tricky subject for most of us, UV is a far more aggressive beast in Western Australia and I dont think anyone would blame you for highlighting a concern, but Paul is indeed one of our experts and he's corrected you (or set the facts straight for other readers) with time served knowledge.
I wouldn't take that as a personal attack, dare I say a bit of googling gains a wider field of knowledge than just this forum alone and helps us brainstorm and deliver the right path forward for the OP and for future Googlers.

 

[Hadenough]

Sorry Paul you are wrong. (BUT the exposure to UV radiation would have to be prolonged)

The Effects of Weathering on Mechanical Properties of Glass Fiber Reinforced Plastics (Grp) Materials
This work has revealed that the decrease in the mechanical properties of GRP under weathering conditions is subjected to atmosphere conditions such as humidity, temperature, ultraviolet radiation and pollution.

https://www.researchgate.net/public...Glass_Fiber_Reinforced_Plastics_Grp_Materials

Whoops, here we go!

 

[coopec]

OP:
I think you'll be fine to do that without any worries IMHO.

Coopec:
This is a tricky subject for most of us, UV is a far more aggressive beast in Western Australia and I dont think anyone would blame you for highlighting a concern, but Paul is indeed one of our experts and he's corrected you (or set the facts straight for other readers) with time served knowledge.
I wouldn't take that as a personal attack, dare I say a bit of googling gains a wider field of knowledge than just this forum alone and helps us brainstorm and deliver the right path forward for the OP and for future Googlers.

Why don't you tell that to the idiot that made the comment #2?

Geeez! There's a few idiots looking for a village here!