The Submersible Deep Quest - A Step Foward in Offshore Technology

Abstract

The Lockheed submersible DEEP QUEST (Fig. 1) is a deep ocean mobile research and engineering test vehicle. It is one of the most versatile vehicles in the exploding family of deep submergence vehicles in that it combines large payload (7,000 pounds or 700 cubic feet), high maneuverability, deep operating depth (8,000 feet) and versatility of missions (large object recovery, coring, diver support). This paper will describe the design, materials of construction, and operating experience of the DEEP QUEST. GENERAL DESCRIPTION DEEP QUEST, with its surface support ship TRANSQUEST (Fig. 2), provides a complete system for deep ocean research and engineering operations. DEEP QUEST is 40 feet long, 16 feet at the beam, and 19 feet across the stern planes (Fig. 3). Displacement is 50 long tons. Lead acid batteries can power DEEP QUEST to a top speed of 4 knots and an average speed of 2 knots for 18 hours. The ma raging steel bispherical pressure capsule (Fig. 4) is 7 feet in diameter and 14 feet long. The forward sphere houses the pilot and co-pilot and all control equipment. The aft sphere provides space for two scientific/engineering personnel and supporting electronic and life support gear. The outer hull (Fig. 5) is free-flooding and is of welded construction using aluminum alloy 5083. All operating equipment (manipulators, propulsion motors, hydraulic systems and television units) are located within the flooded outer hull. The DEEP QUEST is transported by the TRANSQUEST, a 108 foot, 425 ton support vessel. Launch and recovery of DEEP QUEST is accomplished through the TRANSQUEST's elevator located in the ferry-ship stern.(Fig. 6). PRESSURE CAPSULE (Fig. 4) The pressure capsule is a bispherical weldment of 18% nickel maraging steel, heat treated to 180 KSI yield strength and is the first deep submergence application of this high strength alloy. There are three inserts welded into the forward spheres: one for the viewport and two for electrical penetrations. The aft sphere also has three inserts: the top hatch for entrance and exit, the bottom hatch for dry transfer of personnel from a bottom resting habitat (using a transfer skirt and seal) and the aft hatch for access to a diver support chamber. The exterior and interior of the maraging steel pressure capsule is protected by a six coat epoxy-polyurethane paint system approximately 8 mils thick. The system consists of a wash primer (phosphoric acid and resin), epoxy primer, polyurethane primer, and three polyurethane top coats of different colors to insure complete coverage. It was realized that this protective paint system would be damaged during maintenance operations, and for this reason, mildsteel anodes were attached to provide cathodic protection. Mild steel was used to minimize the potential difference (voltage) since cathodic protection studies have shown high strength steels to be susceptible to hydrogen embrittlement where magnesium or zinc anodes had been used. Of particular concern corrosion-wise was the seal interface between the type 316 stainless steel electrical penetrator and the 18% nickel maraging steel hull.