Removing Old Antifouling

[bigmac91]

Apologies if this is covered elsewhere, this is my first attempt at removing old anti foul and was considering using a heavy duty paint scrapper (100mm blade type).

This is on a 38 year old grp hull and my concern is will may damage the old gel coat.
My initial attempts are removing the old flaky anti foul are leaving a mix of what appears to be primer and in places gel coat.

any advise is greatly received

 

[Rivers & creeks]

Doing by hand is possible - but what a job! £300 for complete removal by slurry blasting for our boat with a big underwater area - money very well spent!

 

[richcray]

Being a surveyor I scrape hulls all the time. Whether it is possible to do this by hand really depends on how well the current anti foul is adhered to the hull. I personally use a 'Harris Heavy Duty Tungsten Carbide Wood Scraper' available from screwfix. It allows can be used with one hand on the handle and the other hands palm behind the blade to assert some pressure.
In order not to gouge the gelcoat, consider removing the corners with a file or grinder as these can dig into the gelcoat. Anti foul is pretty horrible stuff, ensure you use cover your skin up, goggles, face mask, etc.
If it doesn't come off easily, think about getting it blasted off. Yachting Monthly ran a series of articles on this a while back, so if you are a YM hoarder it would be worth searching through back issues.

 

[antares]

antifoul removal

We had about twenty years (by the look of it )build up when we bought the boat. It was a terrifying prospect to scrape by hand so we got it soda blasted, they came to the yard and it was highly succesful, I think it cost about £300 . Some gel coat came away in the process so we decided to do the proper job and gel coat, but I'm sure it was the right thing to do and the easiest solution. Good luck, anyway.

 

[bigmac91]

Thanks for the advise,

I have found the old Anti foul is coming away fairly easy, so I assume its a matter of either getting stuck in or pay the money for a slurry blast.
Once the scrapping is done I assume its a good sanding, then primed and a couple of coats of anti fouling.

I don't think there are any issues with Osmosis.

Any recommendations for primer and anti foul. Yacht is being sailed from the tyne for coastal cruising ( April to October) then stored ashore

thanks again

 

[Caer Urfa]

Thanks for the advise,

I have found the old Anti foul is coming away fairly easy, so I assume its a matter of either getting stuck in or pay the money for a slurry blast.
Once the scrapping is done I assume its a good sanding, then primed and a couple of coats of anti fouling.

I don't think there are any issues with Osmosis.

Any recommendations for primer and anti foul. Yacht is being sailed from the tyne for coastal cruising ( April to October) then stored ashore

thanks again

Hi Bigmac91

See you sail from the Tyne, I am not sure where you are based but I am at Royal Quays Marina North Shields and currently ashore in the boatyard, if you want any advice on Hull preparation/antifouling etc just pop round to see me as I am down at the boat most weekends.

I also removed all the old antifoul back to the gel coat in 2010 but used a Bahco tungstine carbine scrapper, but also due to the thickness ended up using grade 40 sand paper and an orbital sander, then 180 grade paper,then after final cleaning down 5 coats of International Gelshields 200, then one coat International Primacon primer, then 2 coats of Micron Extra.

Picture below shows her lifted out last week after being 'in' for just over two years. http://www.google.co.uk/products/ca...=IbTgUIu2NO_L0AXM94GIAg&sqi=2&ved=0CFAQ8wIwAA


Mike (Caer Urfa)

 

[bigmac91]

Hi mike

My yacht "April Legend" came from Royal Quays but now at Friars Goose. It is my first bigger boat so I am learning fast about the maintenance and cost of my new venture !

I have seen your boat and it looks great. I will certainly give you a shout if I am at R Q over the next few week ends.

Thanks for your advice

Les

 

[William_H]

Antif foul removal

By all means give the hand scraping a go. When you get thoroughly fed up with that game (and you will) just smooth of the edges of the last scrape and leave it till next year or the year after. A tedious and terrible job which may put you and your helpers off for ever. It is not essential to get it all off in fact only you will know how far you got. good luck olewill

 

[GrahamM376]

Scraped ours off a couple of winters ago. Very thick multiple layers, dry and flaky so used one of these - http://www.woodworkersinstitute.com/page.asp?p=197 - followed by a two-handed scraper, then finished with random orbilal sander. Not a job I want to repeat but the yard wouldn't allow any blasting. As mentioned above, grind the corners off any scraper blades.

 

[ianj99]

Ice blasting

Thinking of having my steel hull cleaned back to the epoxy primer by a Glasgow company that uses Ice blasting (CO2 I think) which should not damage gelcoat.

The big advantage of CO2 being no residue other than what has been blasted off the hull.

 

[McKimm]

I did mine a couple of years ago with a scraper and would not recommend wasting weekends doing it again! I wish I had had it blasted! Life is far too short....

 

[alahol2]

By all means give the hand scraping a go. When you get thoroughly fed up with that game (and you will) just smooth of the edges of the last scrape and leave it till next year or the year after. A tedious and terrible job which may put you and your helpers off for ever. It is not essential to get it all off in fact only you will know how far you got. good luck olewill

I'll second that, got fed up with scraping mine by the time I'd nearly finished one side. Left the other side till the following winter. I've got the time but not the money so scraping wins. If money no (major) problem I'd definitely go for blasting.

 

[bigmac91]

Removing Antifouling

Got the message guys and after only 3 hours at the boat this morning my super new scraper has been relegated to the depths of my toolbag , hopefully never to see the light of day again . . . Now, where's the number for the slurry blaster guy !

Thanks for all your comments, I have finally come to my senses !

 

[MM5AHO]

I have yet to find a compelling reason to remove the old antifouling. (unless intending to race).
The residual coat thickness is still effective meaning less needs to be applied.
We've not removed back to gelcoat yet, (since 1976). We waterjet any poorly adhered coating and overcoat what's left.

Why do it on a cruising boat?

 

[Caer Urfa]

Got the message guys and after only 3 hours at the boat this morning my super new scraper has been relegated to the depths of my toolbag , hopefully never to see the light of day again . . . Now, where's the number for the slurry blaster guy !

Thanks for all your comments, I have finally come to my senses !

Told you that you would be sanding it off, get some 40 grit paper and an orbital sander AND the safety gear to go with it!

Use the scraper on the waterline edge and pull down, this will give you a clean cut waterline, BUT, remember/mark where the waterline is!!!

Mike

 

[alahol2]

I have yet to find a compelling reason to remove the old antifouling. (unless intending to race).
The residual coat thickness is still effective meaning less needs to be applied.
We've not removed back to gelcoat yet, (since 1976). We waterjet any poorly adhered coating and overcoat what's left.

Why do it on a cruising boat?

Certainly on my boat it was cratered like the surface of the moon. Had it been reasonably smooth (or easily smoothable) I would not have bothered. I have only ever done it once on each of the boats I have owned. After that a power wash and a scrub seems to keep the coating thin enough to not flake for a good number of years.