PS Advisor November 2008 Issue

An Inflatable Bottom Job?

Some suggestions for dinghy antifouling paints.

I have an inflatable dinghy with an air deck, and I want to paint the bottom but do not remember reading any articles regarding bottom paint for inflatable dinghies. The bottom material is Hypalon. I’m asking Mercury, the dinghy manufacturer, but trust your opinion and suggestions.

Fred Fortmiller
S/V Daybreak, Pearson 385
Newport, R.I.

There are two schools of thought when it comes to applying antifouling to Hypalon. We’re of the "don’t do it" camp for a few reasons. First, once bottom paint is applied to Hypalon, it can be very difficult to remove without risking damage to the material.

Second, if you ever store the dinghy on deck or deflate it for longer storage, you can be sure that paint is going to rub off on things you’d rather it not foul—for instance, tacking headsails or the deck, if the dinghy is stored there.

Even if you leave the dinghy in the water for long periods of time without use, cleaning the bottom regularly should be sufficient.

Three Antifouling Boating Paints
Three antifouling paints recommended by Practical Sailor editors, paint manufacturers, and dinghy makers for use on inflatable dinghies are Pettit Hydrocoat, Pettit Inflatable Boat Antifouling Paint, and Interlux’s Fiberglass Bottomkote Aqua.
The folks at Mercury agree with us on this point. Mercury Marine Sales Manager Larry Piechocki told
Practical Sailor, "Once this paint is on the tubes, it will never come off. I’m not a big fan of painting inflatables, but that is up to the customer."

However, if you absolutely have your heart set on applying antifouling to an inflatable (PVC or Hypalon), we recommend using Pettit’s Inflatable Boat Antifouling Paint, Pettit Hydrocoat, or Interlux Fiberglass Bottomkote Aqua.

Practical Sailor editors’ past experiences in the field with Pettit’s Inflatable Boat paint and Hydrocoat have been good, although paint smearing onto other surfaces was an issue. According to Kop-Coat (Pettit) General Manager John Ludgate, Hydrocoat is effective on Hypalon and PVC because it adheres well and is flexible. He added that, "it is ablative, so there may be some rub-off."

In our most recent bottom paint tests (Practical Sailor, October 2008), Fiberglass Bottomkote Aqua—a multi-season hard paint—nailed a recommendation with across-the-board Good ratings after one year of panel testing. Hydrocoat, a multi-season ablative, also was a Recommended product. It notched a Good in Connecticut and a Fair in Florida panel tests after one year.

If the dinghy is to be stored on davits, or out of the water for any length of time, Interlux recommends using its Micron paints, which retain their antifouling properties in and out of the water. The company also warns against using a vinyl antifouling—such as its VC Offshore or Regatta Baltoplate Racing—on Hypalon.

If you have another paint in mind, contact the manufacturer to be sure it’s an appropriate paint for Hypalon.

Whichever paint you choose, be sure to clean the area thoroughly with a maroon Scotchbrite pad for better paint adhesion, and always follow manufacturer instructions.

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