Removing antifoul with the Farrow System or not

[F & L]

My 6 year old Jeanneau 42DS must have been badly anti fouled the first time round because every year pressure washing leaves ever increasing areas of bare gelcoat.
With the build up of antifoul in other places the surface is now very "un-smooth"
I have tried sanding much of the build up and priming the bare patches each year but this does not seem to get on top of the problem.
I now want to get the hull back to basics and have been advised that in Greece (this years wintering is in Kalamata) the Farrow system of slurry blasting by the Greek company Pytheas is a quick and safe method of removing the old Gel coat.
Has anybody out there had experience with the Farrow system or can recommend an alternative way (other than the obvious ball breaking way) with a scraper.
Thanks in anticipation
F&L

 

[gary111160]

Hi.

I have used a slurry blast system in the past couple of years on a much older boat and whilst it did remove all the layers of paint back to the original gelcoat it also left lots of small pin prick holes that had to be epoxy filled and sanded back.

I've just bought another boat and needed to do the same but both the surveyor, who I know quite well and trust, and a GRP repair company who I also trust both said don't entertain it for the very reason I mentioned above.

I'm sure there are varying systems but I opted for the least aggressive. From personal experience I wouldn't have it done again.

I used a hand scraper and I have to say it came off very easily, two days on a 34ft hull. Areas that were firmly stuck I sanded. Like yours the previous layers were not very well done which is why it peeled of easily.

Gary

 

[Tranona]

My 6 year old Jeanneau 42DS must have been badly anti fouled the first time round because every year pressure washing leaves ever increasing areas of bare gelcoat.
With the build up of antifoul in other places the surface is now very "un-smooth"
I have tried sanding much of the build up and priming the bare patches each year but this does not seem to get on top of the problem.
I now want to get the hull back to basics and have been advised that in Greece (this years wintering is in Kalamata) the Farrow system of slurry blasting by the Greek company Pytheas is a quick and safe method of removing the old Gel coat.
Has anybody out there had experience with the Farrow system or can recommend an alternative way (other than the obvious ball breaking way) with a scraper.
Thanks in anticipation
F&L

It is not intended to remove the gel coat, just the paint back to sound gel coat. It is widely used and if done properly is effective. A good operator will know how aggressive to be to remove the paint only. Ask to have a look at work the operator has already done if you are unsure. You may well find it sensible to have an epoxy coat applied over the gel coat before antifoul - or even consider Coppercoat if you are keeping the boat.

 

[lw395]

You may find it's not that much work with a scraper.
It varies, but sometimes, once the AF has fully dried out, if you scrape it with an old chisel it comes off easily in chips rather than dust.

 

[PeterR]

My 6 year old Jeanneau 42DS must have been badly anti fouled the first time round because every year pressure washing leaves ever increasing areas of bare gelcoat.
With the build up of antifoul in other places the surface is now very "un-smooth"
I have tried sanding much of the build up and priming the bare patches each year but this does not seem to get on top of the problem.
I now want to get the hull back to basics and have been advised that in Greece (this years wintering is in Kalamata) the Farrow system of slurry blasting by the Greek company Pytheas is a quick and safe method of removing the old Gel coat.
Has anybody out there had experience with the Farrow system or can recommend an alternative way (other than the obvious ball breaking way) with a scraper.
Thanks in anticipation
F&L

I think the problem is caused by dealers applying primer to new boats without adequately removing the mould release agent.

I had this problem and took the hull back to the gel coat with a tungsten carbide draw scraper. The scraper will separate the antifoul and primer from the hull quite easily - provided it is held at exactly the right angle – if the release agent is the underlying problem. However, this is still not a trivial job - it took me about 4 days for a 34 footer. If you do it this way a tip is to round the corners of the blade to avoid making gouges.

Where I had extended the antifoul above the old waterline and prepared the surface properly the scraping method did not work anywhere near as easily.

If the boat is in Greece scraping is not really practical. I looked at a large number of boats in several different yards that had been taken back to gel coat by pressure blasting and they all exhibited severe pitting in the gel coat. This is probably your only practical solution but painting with epoxy afterwards looks to be essential rather than desirable with this method.

 

[F & L]

Farrow method

Thanks for your reply Peter - still thinking it through. You said scraping was not an option - I assume because of the heat - or is there something else I need to know??
Frank

 

[matelot]

Has anybody out there had experience with the Farrow system or can recommend an alternative way (other than the obvious ball breaking way) with a scraper.
Thanks in anticipation
F&L

Yes. I used Farrow and it worked absolutelky brilliantly leaving a really clean ever so slightly matt surface ideal for epoxy. There arent that many jobs where I dont begrudge the cost of having someone do them, but if I had to clean off another hull I would go back to farrow without a second thought. And I have done the scraping route a couple of times.

 

[mrangry]

I removed many years worth of old paint on a Moody 33 using a simple hand scraper and although a tiresome job it did not take as long as I predicted (couple of days). I found that once you get a certain technique the paint comes off in large thick flakes leaving a clean gel-coat. I used one of those long handled Harris scrapers that you pull towards you where you can change the expensive blades which I think I bought from B & Q.