The Sea Link-A Small Aluminum Submersible
Authors: Wood Charles L. , Kelsey Ronald A. , Dolan Robert B. 
Published: October 2008

ABSTRACT
In response to the need for a small, low-cost submersible for deep sea exploration, a two compartment submersible has been developed that will be made largely of aluminum. The vehicle consists of an acrylic pilots compartment and a separate aluminum divers compartment, with a lock-in and lock-out capability, mounted on an aluminum frame. Propulsion and directional movement is by clustered battery driven electric motors.
The aluminum divers compartment is fabricated of alloy 5456-0. It consists of an unstiffened cylinder measuring four feet in diameter and four feet in length and has two hemispherical ends. Operating depth is 3000 ft. and the collapse depth is 6000 ft. The design is based on a service life of 5000 cycles with a mission duration of eight hours each. All hatches and penetration blocks in both the diver and pilot compartments will be of aluminum.
The framework consists of various diameter aluminum tubular members of alloy 6061-T6. The frame will have spherical joints also of alloy 6061-T6. Mounted on the frame, in addition to the pilot and divers compartments, will be ballast tanks on either side of the vehicle, life support gas cylinders, a gas storage sphere, the propulsion equipment and a battery case. The entire framework is buoyant and is designed to carry gases as needed.
The design of the vehicle demonstrates the suitability of aluminum alloys for the deep ocean environment. The vehicle is versatile and economical and should find wide application in oceanographic research and exploration.

INTRODUCTION
The submersible described in this paper is a development of Mr. Edwin A. Link, the prominent aircraft and ocean pioneer. His concept envisioned a small, low-cost submersible, within the budget of scientific and educational users, and with depth capability to operate over a useful area of the ocean floor. Recalling the excellent service he received from an aluminum diving bell built some ten years ago by Aluminum Company of America, Mr. Link approached Alcoa with plans to design and fabricate the submersible of aluminum. The craft will be donated to the Smithsonian Institution. The program is privately funded on grants to the Smithsonian by Mr. Seward Johnson and Mr. Link.
The "Sea Link" has several features that make it truly innovative. Most important is the fact that its design and construction have produced a relatively simple and lowcost vehicle-- a craft that can be built for about $250,000. A significant feature of the "Sea Link" is an acrylic plastic sphere for the pilot and an observer which permits panoramic visibility underwater. With the exception of the acrylic sphere, the entire vehicle is constructed of aluminum alloys. The "Sea Link" features a separate divers compartment with lock-in and lock-out capability. This makes the craft a true man-in the-sea vehicle, capable of cruising under its own power and providing divers with free access to the sea. Finally, the major components are located in a simple frame, readily accessible and easily removed to facilitate transportation by land, sea, and air.