Diver propulsion
When using propulsion while scuba diving, how is depth controlled?
Scuba diving
Personal mobility is enhanced by fins and optionally diver propulsion vehicles. Fins have a large blade area and use the more powerful leg muscles, so are much more efficient for propulsion and manoeuvring thrust than arm and hand movements, but require skill to provide fine control. Streamlining dive gear will reduce drag and improve mobility. Balanced trim which allows the diver to align in any desired direction also improves streamlining by presenting the smallest section area to the direction of movement and allows propulsion thrust to be used more efficiently. Occasionally a diver may be towed using a "sled", an unpowered device towed behind a surface vessel which conserves the diver's energy and allows more distance to be covered for a given air consumption and bottom time. The depth is usually controlled by the diver by using diving planes or by tilting the whole sled. Some sleds are faired to reduce drag on the diver.