< 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 > The speed increase may come from the GPS antennae not moving around so much. The increased wetted surface is drag. On the other hand, my anti-roll tank, installed in 2001, has required no maintenance, I don't touch it, nor adjust it, there are no moving parts except water; it just sits there completely passive and does its job, which is to reduce roll at about 50%, moving or not. I tell a lie as I did paint the outside of it when I had my upper deck painted, so some maintenance. I did look inside it not too long ago as I was enjoying a glass of wine lounging on the cushions on the top of it, the first time in several years it had been opened. Things in the water, like fins, attract other things in the water, which will necessitate repair, maintenance, and quite likely a trip over the side when you least want to do so. Robert Phillips, Another Asylum, Tortola, BVI