Foulfree from Propspeed, clean transducers without biocide

Boats that spend a lot of time in the water typically have bottom paint applied to reduce fouling growth. Transducers are in the same water as the rest of the boat, but most bottom paint can’t be used on transducers. Unfortunately, the paints compatible with transducers aren’t as effective. Propspeed, the New Zealand based company that makes coatings for props, shafts, and underwater lights, has introduced Foulfree for transducers. Foulfree is a foul-release product, not a biocide and it’s the first product certified by Airmar for use on their transducers.

Transducers are made from materials that can be harmed by traditional oil-based, copper bottom paint. So, transducer manufacturers like Airmar have recommended water-based bottom paint without copper. But, these paints aren’t as effective in preventing growth. Propspeed says their product is a super-slippery coating that coats your transducer and prevents growth from attaching to the transducer without any toxins. They’ve published a thorough explanation of the difference between biocides and foul-release products.

Chris Baird, who recently joined Propspeed as CEO after a long stint at Fusion, introduced Foulfree during a press event at the Fort Lauderdale International Boat Show. The introduction heavily highlighted the environmental benefits of Foulfree as compared to traditional coatings. During his introduction, Baird concentrated on three core features of Foul Free: long-lasting, highly effective, and environmentally safe.

You can see the reduction in sensitivity form growth on the left while the right side shows the performance of a clean transducer

According to Propspeed, Foulfree lasts at least 12 months and longer in cooler waters. They have test boats that are still seeing good results three years after applying Foulfree. Traditional ablative anti-fouling products work by falling away while Foulfree remains in place and slippery throughout its life. Equally important, Foulfree coated transducers can be out of the water for extended layups without any impact on performance.

Propspeed has been using similar foul-release technology in its flagship Propspeed product as well as in Lightspeed, their underwater light coating. Airmar has given a vote of confidence to both Foulfree’s effectiveness and compatibility with their transducers by lending the Airmar name to another company’s product for the first time in Airmar’s nearly 40 year history.

The super slippery surface comes from a silicone polymer. Propspeed advertises that it contains zero toxic substances. Traditional bottom paints use a biocide to prevent growth, by the nature of these products they must contain a toxin of some sort to kill marine growth. The only application consideration with Foulfree is that because it contains silicone care should be taken not to contaminate other areas because silicone will prevent adhesion.

Foulfree is sold in a kit with a brush, surface prep tools and a tube of the product. Application consists of removing any fouling as well as any previous coatings on the transducer, lightly wet sanding the surface, final cleaning and then brushing on one coat of Foulfree. Once applied the coating needs to dry for 8-24 hours before splashing the boat. A complete kit will retail for around $40.

Ben Stein

Ben Stein

Publisher of, passionate marine electronics enthusiast, 100-ton USCG master.

1 Response

  1. November 13, 2019

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