Gelcoating Hull
- Thread starter Graham376
- Start date
William_H
Well-Known Member
I didn't go through the whole story however. the concept offends me. Perhaps it is a case of language changing meaning but...
Gel coat means applied and added to when it is in a gel state. ie it is the first layer of resin applied to the inside of a mold to build a boat in polyester resin.
The next and subsequent layers are applied to the gel coat when it is indeed at a gel state. ie firm but not hard so you get a good chemical bond gel coat to glass and resin layers.
What that means (to me) is that the gel coat when removed from the mold and put in to service is the outer hopefully shiny layer of GRP.
It means that you can never get to use resin (sometimes called gel coat) again for repairs or refurbishing because you can never again get that chemical bond.
You can get polyester resin to stick to a GRP hull by simple mechanical grip. Relying on irregularities of surface to enhance the grip. This leaves people believing that it is a good repair material. In fact polyester does not adhere as well as other resins and shrinks somewhat compared to other resins to make adhesion a concern.
So just because it was originally made with polyester resin does not mean polyester is best repair material. However sometimes due to cost polyester can still be the material of choice.
However back to the video if he is indeed using polyester resin optimised for gel coat use on to an old hull he is using wrong coating.
Paints in various forms are optimised for application to old GRP. 2 pack polyurethane is actually a resin and in paint form is good for adhesion and finish. Then the various modern one pack paints also do well.
So forgive me for getting het up about the word gel for coatings it is all wrong. ol'will
Gel coat means applied and added to when it is in a gel state. ie it is the first layer of resin applied to the inside of a mold to build a boat in polyester resin.
The next and subsequent layers are applied to the gel coat when it is indeed at a gel state. ie firm but not hard so you get a good chemical bond gel coat to glass and resin layers.
What that means (to me) is that the gel coat when removed from the mold and put in to service is the outer hopefully shiny layer of GRP.
It means that you can never get to use resin (sometimes called gel coat) again for repairs or refurbishing because you can never again get that chemical bond.
You can get polyester resin to stick to a GRP hull by simple mechanical grip. Relying on irregularities of surface to enhance the grip. This leaves people believing that it is a good repair material. In fact polyester does not adhere as well as other resins and shrinks somewhat compared to other resins to make adhesion a concern.
So just because it was originally made with polyester resin does not mean polyester is best repair material. However sometimes due to cost polyester can still be the material of choice.
However back to the video if he is indeed using polyester resin optimised for gel coat use on to an old hull he is using wrong coating.
Paints in various forms are optimised for application to old GRP. 2 pack polyurethane is actually a resin and in paint form is good for adhesion and finish. Then the various modern one pack paints also do well.
So forgive me for getting het up about the word gel for coatings it is all wrong. ol'will
Ceirwan
Well-Known Member
@Graham376 I did essentially what he is showing here to the coachroof of my old boat several years ago, & it worked very well, still attached & still has a good gloss.
@William_H The product he applied is called Gelcoat, you're talking about the application method which as you say is normally inside the mold, but however you apply it, its still called gelcoat, or sometimes flow-coat if it already has the wax added to it.
And I think your concern regarding Polyester resin & gelcoat for repair is a little overblown, every resin system will only achieve a mechanical bond when being applied years later, and of course some are stronger than others, that doesn't mean that a perfectly adequate repair can't be made with Polyester (Even if Epoxy is more forgiving), as long as its keyed well, and properly done it works, I've seen some really brutal damage repaired to boats using just poly resin & years of club racing later, they are still absolutely fine;.
Conversely I've seen repairs in epoxy that have failed prematurely when its not been used correctly, poor prep work etc.
This seems a bit extreme, no one is going to respray their boat with a paint system as soon as they get a chip or crack in the gelcoat, again, repairs are carried out on gelcoat with gelcoat every year with good success, perhaps the bond isn't as strong as new, but if its still attached after 20 years, then its done well. I've had good success with gelcoat repairs over the years, the hardest part is colour matching. (for me)
With all that said, only a massochist would attempt a whole boat regelcoat (or someone paid to do it!), the amount of work to flat it all back to achieve a good finish is massive;.
@William_H The product he applied is called Gelcoat, you're talking about the application method which as you say is normally inside the mold, but however you apply it, its still called gelcoat, or sometimes flow-coat if it already has the wax added to it.
And I think your concern regarding Polyester resin & gelcoat for repair is a little overblown, every resin system will only achieve a mechanical bond when being applied years later, and of course some are stronger than others, that doesn't mean that a perfectly adequate repair can't be made with Polyester (Even if Epoxy is more forgiving), as long as its keyed well, and properly done it works, I've seen some really brutal damage repaired to boats using just poly resin & years of club racing later, they are still absolutely fine;.
Conversely I've seen repairs in epoxy that have failed prematurely when its not been used correctly, poor prep work etc.
This seems a bit extreme, no one is going to respray their boat with a paint system as soon as they get a chip or crack in the gelcoat, again, repairs are carried out on gelcoat with gelcoat every year with good success, perhaps the bond isn't as strong as new, but if its still attached after 20 years, then its done well. I've had good success with gelcoat repairs over the years, the hardest part is colour matching. (for me)
With all that said, only a massochist would attempt a whole boat regelcoat (or someone paid to do it!), the amount of work to flat it all back to achieve a good finish is massive;.
potentillaCO32
Well-Known Member
You are wrong. In your conclusion.
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vyv_cox
Well-Known Member
I watched a couple re-gelcoat the topsides of a 38 ft boat in Greece. It took perhaps a month in total. Gelcoat applied by roller, about 3 in all, sanded between coats. An excellent job when polished finally.
Minerva
Well-Known Member
Legend has it, their shoulders still ache to this day!
potentillaCO32
Well-Known Member
I know George and have bought a boat from him.
His work is incredible it is rare to see someone who is such a perfectionist and has such attention to detail. If you want to see true craftsmanship then small outfits like his are the hidden gem. Not many left.
The best piece of detail work I have seen on a boat is his teak and holly floor which he has on youtube. In the flesh it looks even better.
PaulRainbow
Well-Known Member
Sorry, but this is absolute nonsense !!!
If this were true it would be impossible to repair GRP, but we all no this is is eminently repairable. It would also be impossible to build a boat using polyester unless you could assemble the whole GRP structure before any part fully cured. All of those boats built back in the day when some of them took weeks/months to mould/assemble would have fallen apart, but they still seem to be around.
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Graham376
Well-Known Member
There are other videos on his site about this boat including one applying gold leaf to the cove line. As said above, his workmanship is incredible but I dread to think about the cost.
potentillaCO32
Well-Known Member
What is something worth? It is all very subjective. If it is your dream boat and you have the money and want the best workmanship then why not?
But it will only be worth x afterwards despite you blowing 100k on it someone shouts from the back.
Who cares, if it is what you want?
If you go out and buy a new Pogo 30 for 120k and then add another 50k on equipment you will lose maybe 30 - 40k the moment it is delivered. Who cares if it is what you want.
Boat economics never makes sense. It is not meant to. It is a market of dreams.
But it will only be worth x afterwards despite you blowing 100k on it someone shouts from the back.
Who cares, if it is what you want?
If you go out and buy a new Pogo 30 for 120k and then add another 50k on equipment you will lose maybe 30 - 40k the moment it is delivered. Who cares if it is what you want.
Boat economics never makes sense. It is not meant to. It is a market of dreams.
PabloPicasso
Well-Known Member
A yacht is a boat who's only purpose is the pleasure of its owner. Always a waste of money, unless the owner feels otherwise...
Sea Change
Well-Known Member
If you use it enough, it can make sense.A yacht is a boat who's only purpose is the pleasure of its owner. Always a waste of money, unless the owner feels otherwise...
We've been living aboard for nearly five years now, and the rental income from our house in that time has easily paid for the boat.
potentillaCO32
Well-Known Member
Plus your capital gain offsetting boat depreciation.
Minerva
Well-Known Member
J
i might just need to set you up to have a conversation with my wife about that!
Sea Change
Well-Known Member
It only works if your house is somewhere where rental potential is high, and your boat is cheap!