TESTED: PROPELLER ANTIFOUL
We test Prop Defender over a full season
Protecting a propeller from fouling is not easy, thanks to high prop speeds, but infrequent use. There are three possible approaches to take; polished metal, slippery silicone based coatings, or biocidal antifouls.
By the end of the previous season, the generous fouling on the two-bladed fixed bronze propeller on our Sadler 29, Pasque, was costing us 1.5 knots under engine.
Last season, it was time to try something else and we decided to put a new glass-reinforced, silicone-based and hydrophobic product to the test. Prop Defender creates a slippery surface to which fouling will struggle to stick, and should slip off when it does. It uses non-aggressive primers, making it suitable for all metals. It also contains no toxins, solvents, biocides or VOCS.
Application of the original product I tested is in three stages and proved to be pretty straightforward, though needs to be done carefully. Start with a totally clean propeller before rubbing in the degreasing preparation paste with 180 glass paper pad. Next, scrub clean using the supplied detergent, and rinse off with fresh water. Leave it to dry and don’t touch the metal with bare hands, as this can reintroduce grease. I then applied the top coat with a brush – it needs 24 hours before it goes in the water and three days before use.
The company has since updated the product so it now has a two-stage hydrophobic top coat, which it claims makes the finish even more hardwearing and slippery.
TEST VERDICT
Our boat was in the water for a short six months this year and on the whole I was pleased with the performance of Prop Defender. Our speed reduction from fouling was kept to a maximum of half a knot under engine, which is a good deal better than with bare metal.
During the main summer months, there was very little fouling to spot. When we pulled the boat out of the water in late October, after a period of little use, there was very little weed or other growth, though more tenacious coral worm had been able to stick, and any other fouling had grown on this, rather than the metal.
Overall, it wasn’t a perfect solution, but a significant improvement on last season.