I keep my old Marieholm 32 in Vannes, where the water in the marina is fairly warm and brackish - ideal, in fact for the growth of ficopomatus enigmatus. (See Wikipedia for a full description.) This pest seems to prefer bronze/gunmetal fittings as its home, and turns sound screws into misshapen rugby balls with almost no thrust, and so out of balance that the vibration is awful. This year I have had to dry out and clean my screw twice in the space of eight weeks.
I have tried hard antifouling on the screw, but it doesn't seem to stay on. A couple of years ago we had experts out from the marine laboratory in Lorient, but they were unable to suggest a cure.
Does anyone know of a guaranteed method to stop screw fouling when the boat is lying idle?
There is no straightforward answer, but it is quite usual to antifoul a propeller, but you need to use a primer. For years I have been doing this and it works perfectly well. First abrade propeller to get a completely clean finish. The best method is to use a power sander with quite a course grit, say about 120, this cleans it up and gives extra grip for the paint. Ensure you wear rubber gloves, it is important not to touch the bronze with bare skin as it will leave a grease mark that makes the primer fall off. Next a couple of thinned down coats of primer. You can use International's Primocon, which is very good, I have also used Veneziani's specificly designed Propellor Primer which was excellent. After that a couple of thin coats of Hard antifouling. The paint manufacturers say one shouldn't use copper based antifoulings on props, but I have for years with no adverse effect. I also tend to put a coat of soft eroding antifoul over the hard - belt and braces but it works. Over the years I have heard of all sorts of wonder cures, grease, sheeps wool grease, but in my experience none work. I have heard that the East Coast barges used to lay 20 - 30 coats of Grate Black (in NL you would never have heard of it) on the prop. Grate Black is graphite suspended in a very thin oil resin. I have never seen it used so cannot coment on its effectiness, but it sounds rather messey to me! BTW, I do the same with my Volvo Sail-Drive, it works fine and after 7 years there's no sign of any electrolysis or corrosion.
I too have suffered a badly fouled prop - for me it's lots of stubborn little barnacles. Several sailing friends swear by simply coating the prop with lanolin. Apparently the little critters hate it. I'm going to try it this year, not least because it's a lot cheaper and simpler than going down the primer/antifoul route.
I can't answer the question myself I am afraid to say, but I am currently sitting at a computer at the London Boat show and I will print off this thread and see if any of the exhibitors here can help.
I took your question to the very kind gentleman at the International Yacht Paint’s stand and this is what they responded with:
- First you will need to key the surface by sanding it by hand. - Next you will need to apply 4 – 5 coats of Primocon prima (RRP 13.00 – you should only need one tin). - Then you will have to apply 3 coats of Trilyx antifouling (RRP 27.00 – 32.00 exc. VAT – again you should only need one tin). - This should be repeated about once a year though you may not have to key it again if there is still a layer of prima after this period.
All the products are available from International Yacht Paints and for more information, visit www.yachtpaint.com.
They also responded to your comment David about using antifouling on a prop:
It is not a problem to use any copper based product on a bronze prop, however it should never be used on an aluminum one.
Thanks Roxy for your research. Following International Paints suggestion, the cost of antifouling a prop is more than £50,(and a lot of work!)This makes me even more inclined to try the lanolin treatment, even if it does seem too good to be true!
Thanks, Roxy, to you and david evans 5. I agree with David Whitson's thoughts on costs, and found PropShield on the web (prop-shield.com) which claims to be a lanolin based product. At £36.75 plus p. & p. per tub, it too is fairly expensive, but they suggest that there's enough for a couple of seasons on a single screwed boat.
I wonder about the grate black - only about £6 a tube when you can find it, but 20 - 30 coats sounds rather a lot!
I am afraid they all do sound rather expensive so it is probably wise to try the great black solution if you get your hands on some. If it doesn't work, then at least you won't have wasted too much money.
On slightly different note: 'ficopomatus enigmatus' doesn't seem to appear in Wikipedia!
I was sure I'd read about Ficopomatus enigmatus in a Wikipedia article. However, if you Google "Whangarei Marina Baseline survey for non-indigenous marine species", on page 22 of the associated PDF file is a picture showing just what these "hard worms" can do - in a very short time, too.
