Their wings move in a regular rhythm, but said wings do not appear to be their source of either locomotion or lift.
Mandras appear to come in a variety of sizes.
The process by which sailors steer, again according to Shallan, is incredible to watch. Each mandra is harnessed with a ring of pulleys on each side. To steer in the desired direction, the pulley's ropes are shortened on the corresponding side and then retired to the cleats on the ship's railing.