silicone bottom paint, aluminium cat

[Maplemariner]

Does any one have experience with silicon bottom paint on aluminium?

I've seen ships come up on dock after five years of service and just need pressure washing. Aside from the extreme requirements for humility and temperature during application, what are the issues concerning aluminium? I'm also interested in the performance on smaller vessels, namely sailboats.

I'm toying with a long term cruising cat.

[michael pierzga]

The only silicone ? non toxic, bottom paint Ive seen was about ten years ago on military patrol boats. 20 meter boats. The paint was a milky white colour and seemed to work pretty well. The bottoms were fouled but the fouling washed right off.

Perhaps give it a try.

If its not successful...how do you remove the silicone paint ? Silicone is very problematic to paint over and around.

[waikikin]

I've had some, with Intersleek on Supercat ferries on Sydney Harbour, very little growth- only under where the dock blocks were situated & at damaged areas. Was about 3 years old(the coating). In repair areas careful scraping through the slippery topcoat was required for patching in with a multi coat system= some real "gooby" mixes to apply. At the time the vessel operators seemed pretty happy with it.

[Maplemariner]

I've seen it on a number of Holland America ships. They were using international. Yesterday I was talking to a PPG rep and he was saying that it is available in any colour, but it's a pain to apply. I've heard horror stories about massive delamination.

[Maplemariner]

Were the supercats aluminium? Every superintendent I talk to says that the fuel savings are awesome.

[waikikin]

Originally Posted by Maplemariner

Were the supercats aluminium? Every superintendent I talk to says that the fuel savings are awesome.

Yes, they're aluminium & pretty quick(to about 32 but now have a lower, @low 20s cos "stuff" happens too easy at speed in congested waters), get up heaps of hours, I think they trialed Propspeed on them too for the stern gear but I left before that, heard thats good too but exxy.

[mastcolin]

Originally Posted by Maplemariner

Were the supercats aluminium? Every superintendent I talk to says that the fuel savings are awesome.

A few companies supply silicon type foul release products. The most used isInternational Intersleek.


There are no issues with aluminium as the products don't contain any metals. They have very particular priming systems and yes if you get it wrong it can fall off.

They work by foul release ie the speed of movement makes anything fall off. They don't contain any biocides. Note this. It implies a) you have to go pretty fast b) you should be moving as much as possible. "cruising cat" perhaps doesn't fit this profile.

Note that they are also very soft and easily damaged. Don't think of beaching your cat. You may find that you have ground everything off.

Note also that they are hideously expensive when you take into account all the prep and primers. You get your money back if you are a ferry, cruise liner on fuel. Mortals have a big initial capital outlay that isn't quick to repay.

I'd suggest a hard antifouling since you have a cat...and plenty of scrubbing brushes. Beach it every month (you should manage 1st year without much scrubbing if you put on a good few layers) and get scrubbing.