TECHNOLOGY AREA(S): Ground/Sea Vehicles

ACQUISITION PROGRAM: PMS391, Submarine Escape and Rescue Program Office

OBJECTIVE: Develop a solution to enhance the current submarine rescue capability to support shallow-water pressurized rescue.

DESCRIPTION: The Submarine Rescue and Diving Recompression System (SRDRS) provides quick response, worldwide capability to rescue the crews of Disabled Submarines (DISSUBs).� The design of the SRDRS system supports submarine rescue from a bottomed submarine with an intact personnel compartment, to depths up to 2,000 feet seawater (fsw), up to an internal pressure of 5 atmospheres absolute (ata), and up to 45-degree list or trim. The Navy currently has no capability to rescue survivors from a DISSUB with an internal pressure of 5 ata at a depth less than approximately 400 fsw. A solution to allow for pressurized rescue in waters less than 400 fsw is sought. There currently exist no known commercial technological solutions for shallow water mating under pressure, which is why the research and development is needed.

When the Pressurized Rescue Module (PRM) mates to a DISSUB, the hydrostatic compressive force from the difference between the exterior sea pressure and the interior air pressure holds it in place.� To maintain the PRM�s transfer skirt contiguous to the DISSUB rescue seat, this force must be greater than the external forces (umbilical load, hydrodynamic drag from ocean currents, sea state effects, etc.) that are acting to slide, lift, twist, and topple the PRM from the DISSUB.� As a result, shallow water operations are limited by environmental conditions.

The PRM Safe Mating Envelopes (SME) identify the minimum mating depth, such as the shallowest depth measured to the DISSUB hatch/mating seat, necessary to provide a sufficient hydrostatic compressive force.� This is determined based upon the magnitude of the prevailing water current, and the PRM yaw angle relative to that current.� A 0-degree yaw corresponds to a head current, while a 90-degree yaw angle corresponds to a beam current.� The SME�s address mating scenarios where the DISSUB has a list � port or starboard � of 0, 15, 30, or 45 degrees.� The SMEs are based upon a DISSUB internal pressure of 1 ata, which requires adjustment by adding 33 feet for every additional 1 ata that the internal pressure increases, and are applicable up to sea state 4 (wave heights of 4.1 to 8.2 feet) or below.

At this time, based upon the current SMEs the shallow water-mating limit of the PRM is 264 fsw at 1 ata with a 0-degree yaw angle, a 0 degree list, and a 0 knot current.� When internal DISSUB pressure is increased to 5 ata, this results in the shallow water-mating limit being adjusted to 396 fsw.� Consequently, the Navy has no capability to rescue survivors from a DISSUB with an internal pressure of 5 ata at a depth less than approximately 400 fsw.� This results in a gap to the Submarine Rescue mission such that the Navy cannot safely conduct rescues of DISSUBs in more than 40% of rescuable waters.

PHASE I: Research and provide a conceptual solution such that the SMEs allow for pressurized rescue in waters less than 400 fsw.� This concept must use modeling and simulation to demonstrate the feasibility of the proposed solution.� The objective would be conducting safely a pressurized rescue of a DISSUB up to 5 ata at a depth of 100 fsw, with a threshold of 200 fsw, and 0-45 degrees list.� The Phase I Option, if awarded, will include the initial design specifications and capabilities description to build a prototype solution for controlled testing in Phase II. Develop a Phase II plan.

PHASE II: Based on the Phase I results and the Phase II Statement of Work (SOW), develop, build, and deliver a small-scale prototype of the proposed design solution to conduct controlled proof of concept testing.� The prototype must be capable of being pressurized up to 5 ata to simulate DISSUB internal pressure rescue requirements.� Evaluation and testing will provide empirical data verifying mating capabilities in shallow water at increased internal pressures at 0 and 45 degrees list. Prepare a Phase III development plan to transition the technology for Navy production and potential commercial use.

PHASE III DUAL USE APPLICATIONS: Pending successful prototype testing, assist the Navy in transitioning the technology to Navy use and deliver the full-scale design solution for installation onboard the PRM.� Upon installation, conduct testing and evaluation to support certification that will operationally prove the ability of the PRM to safely provide pressurized rescue in shallow waters at 0- and 45-degree list.

Due to the lack of a clear solution to address the increase of mating capabilities, dual-use applications of the potential technology are unknown at this time.� Upon determination of viable concepts, this determination will be revisited.

REFERENCES:

1. Naval Sea Systems Command, PMS391, Concept of Operation for the Submarine Rescue Diving Recompression System (SRDRS) Revision 7; 14 October 2009

2. Naval Sea Systems Command, PMS391, 0A-SRS-OVERVIEW&CL-PM-2-5; Submarine Rescue System Mission Scenarios; Operating Checklists & System Overviews 0A Procedures Manual

3.Gibson, Jim and English, Jim. �Pressurized Rescue Module System (PRMS); U.S. Navy�s Future Submarine Rescue Vehicle.� OceanWorks International Corporation, January 2002.� http://oceanworks.com/admin/sitefile/1/files/OW2002_Pressurized%20Rescue%20Module.pdf

KEYWORDS: Submarine Rescue Diving and Recompression System (SRDRS); Shallow Water Submarine Rescue; Pressurized Rescue Module (PRM); Safe Mating Envelopes (SME); Atmospheres Absolute (ata); Remotely Operated Vehicle