EXPOSURE. A Newsletter for Ocean Technologists. Volume 8, Number 2.
Abstract
The Aanderaa Recording Current Meter (RCM) has been in extensive use at the Bedford Institute of Oceanography (BIO) for six years. From the beginning it was noted that large variations existed between successive compass calibrations of the same instrument. A program was initiated in 1975 to determine the causes of the compass errors and a number of them have been identified and measured. The nickel plating on the older style pressure cases can become magnetized and cause compass errors as high as 12 degrees peak-to-peak at the ambient geomagnetic field intensity at Dartmouth, N.S. (H = 17900 gamma). As reported y Hendry and Hartling (Exposure III(5)), under the influence of the compass's own magnetic field and high pressure, the plating can become sufficiently magnetized to lock the compass in a fixed orientation. It is recommended that at depths of less than 1500 meters the pressure cases should be carefully degaussed just prior to mooring. If the RCM is to be moored at greater depths or in the far north where the horizontal field intensity is weak, the new epoxy-coated pressure cases having nickel only in the upper 0-ring region should be used. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1980
- Accession Number
- ADA085979
Entities
People
- Roderick S. Mesecar
Organizations
- Oregon State University