We have Naiad Zero Speeds on a 78 ft Dutch Built, 10 knot, ocean going boat. Installed them three years ago. Best thing I ever did. My wife & I do not get seasick. Neither does our crew. Looked at gyro's. Seemed to me they are only about 60% effective. The old Naiad's that we had (not zero speeds) were worthless in a big following sea. Had to hand steer the boat, autopilot could not keep up. Old fins weighted 180 pounds each. New fins weigh 1800 pounds each!!!. Following sea now no problem. We anchor all the time and cruise extensively. The boat does NOT roll at anchor. Also on regular cruising they are amazing. No idea the maintenance on Gyro's but Naiad Zero speeds not a big problem. I have NO connection, in any way, to Naiad. Two years ago we were going down the St Laurence Seaway. Anchored in a beautiful very large lake. Flat calm. Went to sleep and about 4 am it starts to blow 45 Kts and 5 ft waves on the beam. Boat rolling like crazy. Crew already up setting a second anchor. I walked up forward but holding on. Takes about 3 minutes for the pressure to come up in the Zero Speeds. Captain throws the switch and the boat STOPS rolling. Go back to bed and my wife says " guess the storms is over" Waves crashing on the beam and winds 45 its.