farmer boy 9:50pm, 6 February 2011
Hi all, I have read all the anifouling info on the site but I am still a bit confused... (never antifouled before!)
I currently have what looks like quite roughly applied red paint on the hull and keel which I guess is antifoul. It is hard and quite difficult to remove - I have had a quick "scrape" to test it.
Is it vital to remove it all (if so.... how?) or can I give it a quick once over with a belt sander and paint (spray?) new stuff over the top?

If it really should be removed can I hire a bead, grit, sand blaster or will that damage the gelcoat underneath - how do the pro's do it and avoid damaging the gelcoat?

Boat is in a shed at home at the moment so a good time to do a "proper" job....

.....also what is "hard" antifoul?

songeur2010 8 years ago
Must Achilles don't have gel coat below the water line, mine did as an exception. Depending on the state of the current anti fouling and how much effort and cost you want to put in will determine your next step. There are people who can blast the old stuff off and one of the UK corespondents will be able to advise who would be best. I was on an extreme budget so did everything myself and used a tungsten scraper to remove the old anti fouling and then cleaned it up with a 200mm 40 grit disk sander. This was hard work but did a wonderful job of exposing the osmosis which then required even more work to fix. I would doubt if you have osmosis based on the there not being any gel coat which seems to be the point of difference between mine and others. If the anti foul is attached nicely you could consider giving it a light sand and anti foul over the top. Most people will roll it on as it is below the waterline so a gloss finish is not required (not that its a gloss product in any case).
There are basically two types of anti foul, hard and ablative. The hard is just that, you roll it on and it stays there and does its job for about a year, the ablative has a surface which slowly erodes away making it impossible for anything to stick and is mostly gone at the end of the year. The ablative is probably the better product once you have a base.
There is another product called copper coat which is more costly but can last up to 7 years with just an annual clean required.
Pop into your local boat shop and see what they have, but if the hull is in good nick there may not be a need for too much hard labour.
farmer boy 8 years ago
That makes sense... many thanks....
blueachilles 8 years ago
Antifoul is toxic, if you do decide to sand it, ensure you at least wear a face mask, and goggles.

"A quick once over with a belt sander " may not do you much good.....

Might be best simply to scrape off any loose bits, and slap another coat on.
Skykomish E29 Posted 8 years ago. Edited by Skykomish E29 (member) 8 years ago
Just a small point, Achilles do have gel coat below the water line, but it is not pigmented. Chris believes that it is the fact that pigment was not added to the mix that the boats are so resistant to Osmosis.

If your antifoul is basically sound, i.e. ALL flakey bits have been removed then as Blue says you can get by with just applying another coat on top of the old.
Be warned though you cannot put hard antifoul on top of soft (eroding) however you can put soft on top of hard.
As has been said unless you plan on serious racing the soft antifoul is probably best as this effectively "washes away" over time, which is what it is designed to do, thus every two years or so you put on a fresh coat (depending on the local conditions, some areas have serious fouling issues and boats have to be done more regularly)

Also most antifouls should only be applied just before the boat is to be put back into the water ( usually a month at the earliest) this is because they require the water to activate them. If you put it on now and don't use the boat until June you may find that you will have to re apply it.

It is a horrid job getting rid of the old stuff, and by far the best way is to have it stripped by a specialist firm like Mr Watts did to Aeolus, they slurry blast the hull and strip it back to the gel coat. If you did that now, you would have the bonus of giving the hull a good few months to dry out reducing the osmosis risk.

Copper Coat is very expensive and locally here on the North Kent Coast it is thought to be a waste of money as most boats live in mud, this clings to the hull and copper coat, and acts as a barrier allowing life to grow on it. I know our yard who is an approved centre don't recommend it .

If you plan, as you should to have the boat out of the water every other winter, then you won't need specialist treatments to the hull, as it will have this time to dry out.
farmer boy 8 years ago
As ever, there is more to this than meets the eye! I will probably get rid of as much of the old stuff by hand and let it dry until I am ready to re-paint and launch.

.....also I have been looking at various Stainless steel fittings.. screws, washers, bolts etc and some say A2 some A4 and some have a number... what is this all about?
busy home [deleted] Posted 8 years ago. Edited by busy home (member) 8 years ago
Use a skarsden scraper in pull mode,,, I tried plane blade, very wide chisel,,, etc ,, they scratch badly on outside edge,
A skarsden is the business ,,
If you do not intend to race no point in going mad!
Smoothing off the steel keel is a challenge , I faired off Goskars with epoxy ,, Still ok two seasons on
PS A belt sander not a good idea,, too agressive too square We use a random orbit but not nice,
rothwell_neil 8 years ago
A2 is 304 stainless steel, perfectly adequate for most marine application also known as 1808 as this is the nominal chrome and nickel composition and is used for sinks. A4 is 316 stainless and has slightly more nickel and 2% molybdenum which makes it more corrosion resistant because the moly improves the passive film and also increases the re-passivation process if the film ever gets damaged. Both are non magnetic austenitic stainless and are preferable to magnetic stainless unless expensive magnetic.

A4 is better for areas that have crevices, get hot or are permanently wet/dry as this concentrates the salt content. Hot stainless cracks with salt so always keep your boat below 60C! Glad you asked now?

The short answer is A2 will do but is A4 is the same price never hurt to get it.
Snow Goose Tim 8 years ago
hey I havnt read everyone elses coments but i deal with large companies Antifouling superyachts on a regular bases. the first thing you want to do is decide what system you wish to use. there are many available, in my experiace jotun imperial is far superior to any other available system. however i am unsure you can buy this on small scale. Once you have decided on a product You need to read the technical data sheets you probably require a primer etc to seal over any existing coatings. it is ok to roll antifoul, but if you want a super slick racy bottom spray apply. I even wet and dry the AF on the boat I race. last of all i really would not touch the boat with a belt sander you create ridges stick to random orbital.

feel free to get in touch if have any questions
farmer boy 8 years ago
Hmmm... I have a lot to learn!
Skykomish E29 8 years ago
Don't worry an Achilles is a great training ground you will be amazed at how easy it all is and how quickly you pick it all up, don't forget you are on a forum here so you are going to get swamped with information but really it is for you to decide what will suit you best, there are no wrong answers just a lot of varying experience from different areas with different conditions.Take a look at Ron's boats and use those as an inspiration, I certainly did.
rothwell_neil 8 years ago
My decision isn't at all difficult from now on as I have found an endless supply of International Interspeed Ultra as no cost to me. Sorry but offer not available to other parties as I did a deal involving a Honda charging plug that has gained me access to the Navy's supplies! Only available in black but black is the new blue in Cumbria.
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