Which Antifouling Paint Should I Use On An Aluminum Boat?

Question: I bought an aluminum 40ft Roberts from the original owner and am in the process of many changes. One area which seems very gray these days is what bottom paint to use. An epoxy barrier coat is there but I do not want any copper impregnated paint anywhere near my boat. Could you please let me know what you’ve found that works.

Answer: Antifouling paint for aluminum boats has been a problem ever since tin based paints were banned. For some ten years we have used the ZO and SN-1 products from ePaint. However, performance has been inconsistent; some years it has worked well lasting up to a year with almost no slime and some years it has grown slime in just a few months. On two occasions it failed completely after just four months, and this in cold water with the boat constantly on the move. The first time this happened epaint replaced the paint but did not cover the cost of recoating. The second time was last year and we did not approach them about it.

As it happens, as I write this we are removing all the paint off the bottom of the boat down to the barrier coat and so are faced with the same difficult decision you are.

The only other option I know of is Trilux® 33 from Interlux. This is a copper based paint but it is copper thiocyanate, which Interlux say is safe for properly barrier coated aluminum boats. We tried the original Trilux product before switching to ePaint and found it pretty poor. Interlux say that they have substantially improved Trilux from the original product that we tried.

The plot gets even more ambiguous: Interlux sells Trilux® 33 in the USA but not in Canada and Trilux II in Canada but not in the USA. Practical Sailor’s tests would seem to indicate that the Canadian product is better than the US product, but when I asked the Interlux technical department, they said the opposite. (I’m a bit skeptical about the Practical Sailor tests since their test rig does not move, which I think may change everything.) At least you can overcoat Trilux® 33 with Trilux II, according to Interlux technical support.

Update, 2007

We decided to stick with ePaint, but with some adaptations.

{ 10 comments… add one }

  • John September 24, 2006, 11:09 am

    Steve Dashew reports that they’ve had really good luck with an industrial system supplied by Ameron, both primers and copper bottom paint. It is possible that you have to start with bare metal, but Steve reports that the bottom paint is better than anything they’ve ever used. Apparently this system has been used on aluminum crew boats for years without problems.

  • John October 24, 2006, 11:10 am

    In the end, after a long and informative telephone conversation with the people at ePaint, we applied ePaint ZO. It turns out that the SN-1 product, that we had poor results with, is too hard for a sailboat and is really designed for fast moving motor boat hulls. The ZO product ablates better at sailboat speeds. This difference between the products is not made clear on the ePaint web site, which seems to imply that the SN-1 is a more powerful industrial strength product, when compared to the ZO.

  • John May 24, 2009, 11:11 am

    See this post for tips on using ePaint.

  • Neil McCubbin September 14, 2010, 5:35 pm

    We were fairly happy with ePaint, but our needs are not demanding. We sail about 6 months, moving a lot, then put Milvina up on the hard for about 6 months.
    For our first year in Europe, we had ePaint on board, and it worked very well.
    This summer, we applied Hempel Alusafe, which has no copper. We can see some grass on the rudder after 6 months in Scotland, but will be hauling in a few weeks so can live with it.
    Many aluminium boats here use Trilux, but I run scared of ANY copper on the hull.

    • John September 14, 2010, 6:00 pm

      I’m with you, Neil, no copper on “Morgan’s Cloud”.

      Who knows, some copper based paints might be OK on aluminum boats, but I don’t want to be the one to find out that they are not!

  • steve August 17, 2011, 2:17 am

    I was not aware that Trilux 33 has any copper in it (worry!). I have used it for the last 2 seasons after having poor results with Trilux. I do have to scrub slime and barnacles every 3 or 4 months, more often if the boat isn’t being used. I would wish for TBT to come back as I believe the French have done a more recent study on its affect on sea life and found that the previous study had overstated the harmful effects, and were supposedly reconsidering the ban. Won’t help down here in NZ though.

  • carsten June 4, 2012, 11:38 am

    Hi, i have a 44 feet alu boat also and just bought . it is 20 years old and allways used copped based antifouling w/o any problem. so i stick to it. it has a epoxy coat plus vinyl and i use now ecoship / relies Basf a commercial grade AF. Let see … Last year i tried Seajet but poor result against barnacles.

  • Pat Carriere July 14, 2012, 11:02 am

    I’m using Trilux II since many years without problems on my Aluminium boat (AG4) builded in 1974. Each years I inspect the hull and until now, no sign of electolysis. (I have initially applied 3 layers of InterProtect 2000e on the hull)

  • Mark Anderson January 19, 2014, 10:48 pm

    I have x 2 aluminium pontoon boats that I use for hire/drive – have been using Lanolin for some years to help protect hulls – looking seriously at anti-fouling both boats for longer protection in salt water – I am a bit “gun shy” about reports I have read on antifouling – does anyone have any experience using a suitable anti foul.

  • Mike Shaw March 26, 2014, 4:30 pm

    Mark, I also have a pontoon boat which I just purchased new, I am confused as to which product to use. I will be keeping the boat in salt water in Delaware, any advice would be appreciated.


Leave a Comment

Please read our Comment Guidelines before you comment.
If your comment does not display immediately, please contact us
Your e-mail address will not be displayed and we will not send you junk mail.

Get your own avatar like ours.