Applying 2 pack epoxy to hull

morgandlm

morgandlm

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After much deliberation I have decided to go ahead and epoxy Bonsella's cleaned off hull. Bonsella is a Sadler 26. Can folks please offer some practical advice how best to go about this most economically. I will do the work myself. Assuming that I choose Gelshield 200 - how far should I expect the stuff to go? Should I buy it in 2.5 litre packs or smaller? Brush or roller? I assume it is then primer and antifoul - or does the epoxy act as primer? Grateful for any advice.
Morgan
 
Gelcoat should be abraded with something like 80 grit with orbital sander before you put anything on top. Think twice about using Gelshield. It's solvent-based, which never made sense to me: the idea of a barrier coat is that it should be thick enough to work (min 0.5mm), yet Gelshield is solvent-based so much of it simply evaporates. It's also expensive.

I'd suggest you use a proprietary solvent-free epoxy from a specialist supplier. Explain to them it's for a barrier coat and they'll come up with the right stuff. Don't be tempted to use West: also expensive, and very prone to amine blush (a waxy surface coating in cool, humid conditions...i.e. wot the UK does most of the time).

Whatever you use, apply by roller. Again, ask epoxy supplier to specify which kind. They'll probably have them quite cheap. Brushing is only used for very fiddly bits.

Epoxy can act as a primer for certain finishes: ask your antifoul supplier. However you'll probably need a specific primer. Coppercoat sticks to 'green' solvent-free epoxy very well, but perhaps that's expenditure too much. Worth thinking about, though, after all the trouble you've gone to.
 
I used Gelshield 200 on a Tomahawk 25. IIRC, a 750ml tin was barely enough for 1 coat, applied by brush. Dividing up a 2.5 litre tin was more economical, but troublesome. It was simple to apply, and gave no problems over the next several years. Application conditions need to be right, not always easy pre-season.
DIY preparation, ie stripping A/F and thoroughly abrading can be a lot of hard work.
I applied A/F direct to freshly cured Gelshield, as recommended by International at the time.
For a boat of age such as a Sadler 26, if it hasn't got problems by now, then I'd question the value of the work and expense.
 
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macd said:
Gelcoat should be abraded with something like 80 grit with orbital sander before you put anything on top. Think twice about using Gelshield. It's solvent-based, which never made sense to me: the idea of a barrier coat is that it should be thick enough to work (min 0.5mm), yet Gelshield is solvent-based so much of it simply evaporates. It's also expensive.

I'd suggest you use a proprietary solvent-free epoxy from a specialist supplier. Explain to them it's for a barrier coat and they'll come up with the right stuff. Don't be tempted to use West: also expensive, and very prone to amine blush (a waxy surface coating in cool, humid conditions...i.e. wot the UK does most of the time).

Whatever you use, apply by roller. Again, ask epoxy supplier to specify which kind. They'll probably have them quite cheap. Brushing is only used for very fiddly bits.

Epoxy can act as a primer for certain finishes: ask your antifoul supplier. However you'll probably need a specific primer. Coppercoat sticks to 'green' solvent-free epoxy very well, but perhaps that's expenditure too much. Worth thinking about, though, after all the trouble you've gone to.
Click to expand...

Sound advice, ME100 will be way cheaper than Gelshield and its water based.
 
Whatever you use, wash the hull with Acetone BEFORE you sand it and BEFORE you coat it.

Not cleaning the hull prior to sanding will only help spread contaminants.

Not cleaning the hull prior to application of you chosen product means you will not get get good adhesion.

Good luck and fair winds. :)
 
I used Gelshield 200 when I prepared the hull of my boat from new & a 2.5 litre tin did one coat on a 32ft hull with twin keels.

Preparation was to sand the hull before and that was the worst job - took about 2 days with a random orbital sander as you must get rid of any shine on the gelcoat. Should be easier on a hull that has been prepared before.

IMPORTANT - Gelshield is NOT a primer and once it has cured you will have to add a coat of primer, preferably of the same make as the antifoul you are going to use to avoid any chance of incompatibility. If you don't prime first, there is every chance that the antifoul will just flake off. I know from past experience on a previous boat.

Not a difficult job, just time consuming as you are probably looking at one coat of Gelshield a day unless you have the luxury of a heated indoor space.
 
I used Gelshield 200 in about 2001, not sure of the exact date and I don't recall how much I used. It was five coats in all, alternating grey and green, then a coat of scrubbable antifouling applied when the final coat was still tacky, to act as a primer. There's a photo of me applying it here http://coxengineering.sharepoint.com/Pages/Legs.aspx

Despite the negative comments it has been extremely successful and the previous minor evidence of osmosis has never been repeated.
 
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This is not a pleasant job. I have no experience of water based epoxy used below the waterline so am not in a position to comment. Gelshield 200 is certainly an excellent product and will serve you well. Hempels make a similar product called SFE200, I used this on my own boat from new. The reason I chose Hempels, or Blakes as it was know back then, it that you don't need so many coats as with Gelshield. The most important thing to do is to follow the manufacturers instructions to the letter. Both International and Hempels provide really good post sales support.
 
galadriel said:
ME100 will be way cheaper than Gelshield and its water based.
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I've used it and it's good stuff. But I'd swear blind it's not water-based.

oldsaltoz said:
Whatever you use, wash the hull with Acetone BEFORE you sand it and BEFORE you coat it.
Click to expand...

Washing with acetone is not the best advice. At the very least it runs the risk of solvent entrapment under the subsequent epoxy unless allowed to dry very thoroughly (which is why the Coppercoat people urge you in very bold letters not to do it). A week's drying would not be too long...by which time it'll need another wash, in good old soapy water, followed by a thorough rinse.
 
The tech dept at the epoxy supplier will advise you on coverage - I used Blakes and it went well. I used rollers but you need proper epoxy rollers available from most chandlers. lots of disposeable goves, mixing pots, mixing sticks and some normal pain trays to pour the mixed epoxy into. I did it all myself which meant the finish was left " as rolled" and took a nice dimpled sort of surface - like a much smoother golf ball. The jury was out when racing as to whether this finish gave me an advantage or not, but it certainly wasnt a problem. If you want it smooth then you need a second person with a supply of brushes to finish it off where you have rolled.

Its an easy job not much different to applying anti foul.
 
I was supplied with ME100 as part of my Coppercoat order. As discussed above, ME100 is a solvent free industrial epoxy.
On the upside, its much cheaper, goes on in two coats and doesn't carry the risk of trapped solvent causing blisters. On the downside, it has to be applied before the first coat is curred and is more sensitive to temperature and humidity. I scarred myself to death during March (2009) mixing samples to understand behavior at various temeratures and humidities.... so much so that I almost switched to Gelsheild!

I was lucky enough to catch some exceptional weather at the end of March ... Thursday 1x ME100, Friday 1xME100, Saturday 4x Coppercoat. Two years on, all is well, and as a bonus I had enough left over for the garage floor.
 
I scraped off years of antifoul on my 29 foot four years ago, sanded thoroughly and then applied a 2 pack proprietary epoxy supplied by http://www.arccompany.co.uk/ - the contact I dealt with was Mark. The company was extremly helpful with information and tips on getting the job done. I applied 5 coats, alternate black and grey. It was a very sunny few days in April, temp over 20 c, so I was able to get a couple of coats on in same day. Subsequent coats need to be applied while previous is still 'tacky'. I applied jotun vinyguard on finsied expoxy as a primer before applying antifoul. Hardest part of the job is removing the old antifoul and preparing the surface for the epoxy. Applying the epoxy was quite straightforward using a roller. On annual liftout since, it all seems to be fine, so I am very happy with the overall job and products used. So as recommend in above replies, I would suggest you go with a proprietary epoxy from a specialist supplier.
 
Quote Originally Posted by oldsaltoz View Post
Whatever you use, wash the hull with Acetone BEFORE you sand it and BEFORE you coat it.

(Quote)Washing with acetone is not the best advice. At the very least it runs the risk of solvent entrapment under the subsequent epoxy unless allowed to dry very thoroughly (which is why the Coppercoat people urge you in very bold letters not to do it). A week's drying would not be too long...by which time it'll need another wash, in good old soapy water, followed by a thorough rinse.(End Quote).

Do you honestly thing that soap and water will remove contaminants like silicon and other chemical residues.

Good luck and fair winds.
 
oldsaltoz said:
Do you honestly thing that soap and water will remove contaminants like silicon and other chemical residues.
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Er...I honestly thing where's the silicon come from? There's none on my hull, nor that of any boat I've owned. Besides, acetone would just spread it about. And AMC (the Coppercoat people) know very little about hulls. Obviously.
 
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