Project Title: An Autonomous Profiler for Estuarine Research and Monitoring
Principal Investigator(s): Rocky Geyer, Daniel Frye and Kenneth Doherty

Summary
During this period the underwater winch was designed and built (see photograph). This includes all mechanical and electrical/electronic components. Preliminary software has been written to test the winch design and bench tests are about complete. Shallow water dock tests will start next week.

Detailed Description of Accomplishments
The underwater winch system, designed as proposed, consists of three basic mechanical units: battery/electronics housing, turning block and an electric motor driven winch. These mechanical units are packaged in a welded frame constructed of 1.6-cm dia, type 316 stainless steel rod stock. The frame measures 90cm long, 50cm wide and 41cm high. The complete package weighs 95 kg in air and 45 kg in water. Four short feet are welded to the bottom of the frame to attach flat shoes or spiked tubes depending on the expected bottom consistency.

The battery/electronics housing is machined from 30.5cm o.d. by 2.5cm wall 6061-T6 aluminum tubing and the end caps are machined from 2.5cm plate. The housing and endcaps are hard coat anodized with zinc anodes attached to both endcaps to mitigate seawater corrosion. The housing contains the battery pack (210 alkaline D-cells), a microprocessor (TattleTale 8), power supplies and necessary electronics. This battery is more than adequate to do hourly profiles in 20m of water for 60 days. The front-end cap has two electrical penetrators, one to power the winch electric motor/brake and one for programming the system before deployment. The housing is attached to the frame by rubber covered stainless steel u-bolts.

We chose not to use active level-winding, because there is a good possibility of fouling such a device. Instead, we are relying on a small cable fleet angle to maintain even level-winding. To accomplish this we placed a turning block 50cm from the winch drum, which reduced the fleet angle to 2.5 degrees. This block is machined from wear resistant plastic and uses Torlon balls for the bearing. The turning block is mounted to the frame and is allowed to rotate to align with the direction of current.

The plastic winch housing contains a 150-watt brush-type electric motor, a 100:1 ratio gearhead and an electric brake. Since the brake cannot work reliably in oil we are running these components in air. This poses a risk of flooding the housing, but we believe that our design will prove reliable. A stainless steel shaft sealed by an o-ring connects the gearhead to a plastic drum that holds 30m of 7/64 diameter Spectra rope. This unit is securely bolted to the frame.

Present Status
We are a little behind schedule, but expect to make good progress now that the winch is completed. Our focus for the next phase will be further testing of the winch to tweak the software algorithms and to design the buoyant instrument pod.

We are still on track for local field tests of the complete system in the early spring of 2002 and deployments in Winyah Bay and the Hudson River estuary by June, 2002.