View Full Version : old and new antifouling

martin schulz
03-01-2002, 12:45 PM
I am taking my boat out next month and I have two things to do on which I would like your opinions.
1. I still have "old" antifouling on hull. That is the kind of anti-fouling which is toxic (because of lead, copper or zinc in it). Those antifoulings are not allowed anymore over here, and I have to put new non-toxic antifouling on. That is the kind that washes off, so algae and clams can't cling on the hull.
Question 1: Can I just paint the "new" antifouling on the "old" one? or do I have to strip the "old" one completely off?

2. I would like to paint the hull black. To avoid troubles with my now white hull and the antifouling on it - again - do I have to strip the antifouling off, paint the whole hull black and then put the new antifouling on the hull under the waterline?

...thanks ahead - Martin

03-01-2002, 01:27 PM
Well, I'm not expert ... but, I did NOT strip mine completely off. I'm in freshwater.

I painted new over the sanded/scraped old stuff ... Two years later, it is still fine.

There may be a better way ... but that has worked for me. Like I said ... I'm not the end-all anti-fouling expert.

What are the troubles with your white hull that would make you want to paint it black? Don't get me wrong ... I love dark hulls, I am just curious.


Bob Cleek
03-01-2002, 05:54 PM
LFH, perhaps paraphrasing Henry Ford, is said to have observed, "There are only two colors to paint a boat and only an ass would paint one black." Just a thought... it's your boat! LOL

BTW, seems to me "non-toxic antifouling paint" is a self-cancelling concept, no? Sounds like sort of the same kind of thing as "safe hand grenades" to me. You WANT it to kill the buggers! God save us all from the misguided regulators! It isn't like bottom paint is going to extinguish the barnacle and algae gene pools!

martin schulz
03-02-2002, 09:30 AM
Brad and Bob,
sorry - but I had this discussion before. I own a 50 year old sort of Pilot-Cutter replika. The boat lies in a museum-harbour with more or less only "working" boats (mosty 2 mast fishing vessels). I do not own a gleaming white and mahogany yacht. Usually working boats were painted with what is cheapest and most effective - not what is shiny.

The white hull is in my opinion too yacht-like. I bet, that was the look the former owner wanted his boat to look like, lying in a yacht-club. For me there is no need for "dinner-jackets" anymore, since I feel at home between all those big old working boats. http://www.sh-tourist.de/rumregat/images/rumregmi.jpg

Dale Harvey
03-02-2002, 10:03 AM
You will have to consult with the manufacturer of the new paint. No one else can tell you. That said, I would go to great lengths NOT to strip ANY well adheared old paint. That stuff worked to keep worms out, and the new stuff won't. By coating over it, you will still preserve it's benefits as a secondary line of defense. Even if you arre prohibited from useing the good stuff as primary paint, it is doubtful that the goons who make the regulations were smart enough to prohibit the use of toxics as PRIMER under their new crap. Check it out, and if this is so, make your own toxic homebrew if neccesary, and slather it on UNDER the required topcoat of useless goop. That way when the worms start chewing thru, they will find something that dulls their appetite before they can riddle your wood.

03-02-2002, 10:54 AM
To anybody,

The question of antifouling paint and other glop raises a question of perhaps historical interest.

Before the invention of antifouling paint, there was copper clading, thin copper sheets, perhaps 6 by 12 inches square nailed to the hull with a layer of tarred felt between the copper and the wood. You can see this on the Cutty Sark at Greenwich. This was expensive, but it worked.

The other method was to tar the hull, after burning off the marine growth while the boat was high and dry at low tide. I don't know what they did where there was not much tidal range. Then they retarred and over the tar applied a gloppy mixture of tallow (boiled animal fat) and lime. This was white.

The tallow gradually sluffed off, and did not provide a grip for marine growth and the lime, probably because of alkaline pH discouraged growth.

My question is : how long did this treatment last before it needed to be done again?

I think the lime and tallow didn't last very long and this may be the reason for some of the critcisms of Columbus's proposed voyage. His ships would foul so badly before he reached China that they would become unsailaable in mid ocean. Any ideas?

Roger Cumming
03-02-2002, 03:43 PM
Bob, it was Captain Nat, not LFH who said it. And he said, "fool", not "ass".

In any event, it would seem logical to deal with topsides and bottom separately. Paint the topsides with enamel, and understand that expansion and contraction during the summer will be more severe with black than with white or any other more reflective color. If the boat has smooth carvel planking, you may get cracks along the seams when they move relative to one another.

On the bottom your choice would be "ablative" (poison leaches out, but not the paint) or "sloughing" (paint and poison drops off). The former is a hard (epoxy) paint which builds up and then must be removed. The latter is soft paint that builds up much more slowly, because much of it washes away during the season. The former is more expensive than the latter. Interlux's "Bottomkote" is a soft, sloughing, old fashioned paint with a fairly ok copper strength. Red or Blue. It isn't even listed in catalogs such as West Marine, like caulking irons and other useful things. You have to ask for it. But I digress..