Hawaii Teacher on Board
Standing Watch

By Larry Gaddis

Oct. 7, 1998. We are settling into the routine of a scientific research vessel. Mapping the ocean floor in high resolution is tedious and time consuming so our time at sea is precious. Accordingly, our ship continues its work 24 hours a day. We have scheduled assigned watches around the clock. My watch is from 8:00 p.m. to 12 midnight in the DSL control van.

It takes four people to man the control room, a navigator, a flyer, a sonar operator and a watch leader. The flyer operates the DSL120 which is the sounding vehicle tethered to the ship. We have affectionately dubbed the DSL120 as "the fish." It is the flyer’s responsibility to keep the fish within 125 meters from the bottom for good sonar readings. The flyer’s most critical responsibility is to keep the fish from hitting the bottom as this collision would severely damage the vehicle and potentially terminate our project.

Flyer, Will Sellars, at the controls
Flyer, Will Sellars, at the controls.

The flyer must control the fish up to 3.5 miles below the ship and several miles behind. At the opposite end of the tether from the fish is the ship. It is the navigator’s responsibility to maneuver the ship so that the fish exactly follows a predetermined line for gathering data. This requires constant monitoring of the position of both the ship and the fish. Properly positioned, the fish follows the predetermined line, scans the ocean floor using side-scanning sonar, and transmits the data digitally back to the ship via fiber optic cable. The sonar operator monitors the many screens which help the flyer keep the fish a safe distance from the bottom and ensures that the sonar, bathymetry, and magnetic data are all being properly recorded for later analysis. The watch leader records the position of the fish along the line and makes note of unusual or interesting features discovered there.

Line on chart show distance of vehicle from bottom
Line on chart shows distance of vehicle from bottom.

My watch assignment is sonar operator. Imagine sitting for four hours in a cool, dark room illuminated only by computer monitors. Our watch leader is Frank Trusdell and he keeps us all from getting sleepy with lively humor and chocolate covered coffee beans. An ever changing variety of great music completes the watch experience.

Screen used by navigator to control ship & fish position.
Screen used by navigator to control ship & fish position.