A performance update of the InterOcean S4 electromagnetic current meter

Abstract

This report reviews the working principles of the InterOcean S4 electromagnetic current meter and outlines the practical difficulties and engineering solutions to convert these basic principles into a working instrument. Presented are the test procedures and results performed on three production units placing emphasis on the oceanographic users point of view. These tests, performed by the Ocean Structures and Moorings Laboratory, Ocean Engineering Department, Woods Hole Oceanographic Institution (WHOI), include laboratory, dockside, and both surface and subsurface mooring tests. S4s are compared to each other and to other types of current meters in various intercomparison tests. Results of. this evaluation program are next summarized. Also, suggestions for areas of improvement and further developments are made. Finally, recommendations for the acceptance, calibration, and burning in of new instruments conclude the report.