(Woods Hole Oceanographic Institution, 1980-05)
Bitterman, David S.
A ship towed log for use on ships-of-opportunity to measure ocean
surface currents was built and tested over the past two years. The technique
used is one of the oldest known to navigators. The ship's dead
reckoned position is calculated from the speed and heading as measured by
the towed log. This is then compared to the ship's true position as
obtained from a reference navigation system (Loran, satellites, etc.) and
the difference is attributed to the currents encountered by the ship. The
system was used on six sea cruises and was successfully towed over 11,000
miles. While it i s not capable of making high precision current measurements
as would be obtained from moored current meters, it can distinguish
features on the order of 20 to 30 em/sec. over a large horizontal scale
in the upper ocean.
