Get the best performance possible out of your transducer. Propspeed and Airmar have worked together to create Foulfree, a specialized foul-release coating that is biocide-free and does not poison marine growth. Once cured, Foulfree forms a super-slippery surface over the transducer, preventing marine growth from attaching to its surface. This means your expensive electronics package is going to give true returns and not be hampered by a layer of growth that can give false readings.
How much do you need? Use this calculator: Propspeed Coverage Calculator