PS Advisor August 1, 2002 Issue

PS Advisor: 08/01/02

Freshwater Bottom Paint?
As a very long-time subscriber to PS, I have read every issue about every subject imaginable.  Not only in your publication but also in the four or five slicks in which I also indulge, bottom paint, blisters, varnishes, and the like fill up a lot of space. One thing I have noticed is that nowhere, not in the ads nor in the expert articles, is there ever any mention of separating bottom paint into the two most obvious categories— paint for salt water and paint for fresh water.  No tests, no discussions, no difference in paint types, chemical make-ups, literally nothing. 

Your tests are conducted in salt water.  There must be a difference in additives and chemicals that work better for the specific problems of slime and the like that affect fresh- water boats. A lot of the stuff in bottom paint is to repel the effects of creatures and things that are prevalent in only salt water.  I don't think I need all that in an inland lake.  Maybe if bottom paint is good for salt water it can't hurt in fresh.  Maybe.  But I can't help but think that the manufacturers could specifically make a paint that was really effective in fresh water. 

-Allan Berman
Dallas, TX

It's true that not much is made of this issue, and our usual response to such questions is pretty simple: A paint that deals with fouling in salt water will do even better in fresh. It's true that there could be all sorts of formulations for freshwater paint, but since copper, zinc, and the various algae and slime killers that already exist in bottom paint are "broad-spectrum" biocides, it's probably not worth the time and effort on the part of paint makers, or the cost to boaters, to pursue those formulations.

In any case, we thought we'd ask a real paint manufacturer to comment on the topic, and this is what we received from Jim Seidel at Interlux:

"There are many things that affect the way antifouling paints work, including alkalinity, salinity, and water temperature as well as differences in fouling challenges. We have to test paints in as many environments as we possibly can. Antifouling paints that work in saltwater will generally work in freshwater, but the challenge is different. For most freshwater areas the biggest challenge is not shell fouling but weed and slime growth. Shellfouling is relatively easy to control by comparison to weed and slime fouling: It takes a much higher release rate of cuprous oxide to control weed and slime growth than it does to discourage zebra mussel or barnacle attachment.

"While most antifouling paints are not formulated for freshwater only, we must take into consideration how well they work in fresh water, and we would not launch a paint that did not work in fresh water. To that end we have two test sites in fresh water, one in Lake Erie near Cleveland, and theother in Lake Texoma, which is about 90 miles north of Dallas.

"In northern areas, where the water is colder and seasons are shorter, hard paints work well in just about all conditions, probably because the releases rate of the biocides are not affected by the water temperature. Water temperature does affect the wear rate of the copolymer and ablative paints, and in extreme cold freshwater it may not polish enough togain the advantages that  copolymer and ablative paints offer.

"We have only one paint that we recommend for freshwater only, and that is VC17m. It has worked very well in the Great Lakes and in warm freshwater lakes like Lake Texoma but because of the nature of the paint and the fouling challenge it usually only lasts about 10-12 months at the test site in Texas. We have been working extremely hard over the past couple of years formulating a version of VC17m that will be able to take advantage of the Biolux technology."

Allan, Practical Sailor has samples of this new paint, VC17m Extra, on our new panels, which are in the water in Connecticut and Florida. We'll let you know all the results next spring.


What's Your Handle, Mate?
I've not been able to find a source that will tell me what constitutes good VHF radio etiquette now that a FCC station license is no longer required. The Yacht Racing Association of Long Island Sound requires me to have a VHF radio.  What might the "call letters" be?  Someone suggested that the state of registry abbreviation plus the sail number is sufficient.

-Bruce McPhersons
Via e-mail

Bruce, see the following web page: The operative quote is this: "You may identify your ship station over the air using your FCC-issued call sign, maritime mobile service identity (MMSI), the state registration number or official number of your ship, or the name of your ship."

As for good radio etiquette and speak/listen procedures, they've vanished in the crowds.

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