hi,these are passive stabilizers,they are also fitting a forward brace to stiffen it up which should also deflect any pot lines etc.two commercial boats with these fitted have reported ability to stay working longer in 30 35 knot conditions plus one boat estimated a .5 knot increase in speed due to increase in lift as the fins are an aerofoil section.boat will be back in water on friday looking forward to seatrials cheers greg