Principal Investigator: Clifford A. Goudey, Kenneth D. Ekstrom

Summary:

The planned phase one feeder system is under construction and will be available for installation at the UNH OOA demonstration site in early 2001. This system, Robofeeder P1, will have a 500 pound capacity and provide for autonomous dispensing of feed using an electronic timer that controls a solenoid and air operated gate valve. The system will be upgraded to submersible operation using an air compensation system. An additional submersible system will be built for the Gulf of Mexico Consortium cage. Video telemetry and remote control feeding will be added to these systems.

Introduction:

This project began as a progressive approach to the development of a suitable feeder system. First, a surface feeder was going to be developed along with the means to operate and monitor feeding through am rf telemetry link. Then, in the second year. the additional challenges of operating a feeding system while submerged would be undertaken.

However, recent developments associated with the UNH site, the initiation of the Gulf of Mexico offshore site, the encouraging results of the Hawaii cage, and current market opportunities for submerged cage technologies reveal new urgency in the development of a submerged feeding system that is properly integrated into the Sea Station cage. Therefore, with the encouragement of Dr. McVey of the National Sea Grant Program, a revised proposal was submitted to accelerate the development and integration our system into the OST cage through the direct involvement of engineers from the supplier of the cage systems.

Under our revised plan, our activities related to rf telemetry will be preceded by the development and testing of the feeding systems themselves. Therefore, our initial development goal has become the design and construction of a surface feeding system that can be operated automatically with a timer. This would allow the implementation of unmanned feeding at the UNH site without the necessity of implementing the telemetry link.

Specific progress to date:

Objective 1) Collaborations to identify system requirements

We have established collaborations with OST engineers and with project coordinators at the UNH and Gulf of Mexico cage demonstration sites. Required feed capacities and feeding requirements have been clarified. The exchange of design and engineering information with OST is in process.

Objective 2) System design, construction, and assembly

The initial prototype system will be built around a 110 gallon polyethylene cone-bottom tank. This low cost industrial unit is modified to be water tight and able to withstand internal pressure. A port for filling is provided and a custom designed cone adapter has been added. The exit of this tank is fitted with a pneumatically operated 3" gate valve which leads to distribution pipes that direct feed pellets to either side of the cages central spar. Flow of the pellets is ensured through the introduction of streams of sea water below the gate valve.

The gate valve is opened by air pressure from a scuba tank and a first-stage scuba regulator controlled by a solenoid valve and a timer. Positive valve closure will facilitated by spring loading. The hopper and valve are shown in Figure 1.

The polyethylene hopper is mounted in a galvanized steel silo that will mount on the center of the spar platform. This silo will protect the hopper, the air tanks, and the electric and pneumatic systems from wave damage and vandalism. This silo and it's mounting on the Sea Station&trade.

All sensitive components will be housed in water proof containers within the base of the silo and tolerant of submersion. Prototype I will not include pressure compensation for the feed hopper and prolonged submersion will result in flooding of the hopper and soaking of the feed.

This hopper/silo system will be able to be retrofitted with the pressure compensation system once that feature is successfully developed and prototyped.

Objective 3) System testing

A mock-up of the pressure compensation system was successfully tested in August. This system uses the diving-bell principal to keep water out of the feed hopper. A float senses the air/water interface in the tube below the feed gate valve. If water advanced to the level of the float, air is released into the hopper. The converse is accomplished by air leaking our the lower end of the feed dispenser.

Compensating air will be contained in scuba tanks stored in the base of the silo. The compensation system is mechanical and does not require electric power, sensors or actuators. Air consumption will be a function of the frequency and magnitude of depth changes.

Objective 4) System installation and evaluation

Pending

Objective 5) System installations

Pending

Objective 6) Project dissemination

Outreach has begun with our interactions with the cage demonstration sites and with OST. Mechanisms for cooperation with industry in the commercialization of our emerging technology are already being explored.