How good are current meter data?

The usefulness of current meter data is discussed from the point of view of how errors show up in both the time and frequency domains. Three situations are discussed: a perfect current meter on a moving subsurface mooring, a current meter with a threshold response problem on a perfect mooring, and a rotor-vane current meter on a surface mooring. Several presently available current meters are subjectively compared as to their usefulness in various situations. Two major conclusions are that one type of current meter is unlikely to be the optimum choice for all applications, and that new designs should pay just as much attention to mechanical and hydrodynamic design as to electronics.