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	Director, Operational Test & Evaluation
FY97 Annual Report

COASTAL MINE HUNTER (MHC 51)

	Navy ACAT 1C Program 12 systems Total program cost (TY$) $1730M Average unit cost (TY$) $143M Full-rate production 2QFY90 Prime Contractor Intermarine USA Avondale Shipyard

SYSTEM DESCRIPTION & CONTRIBUTION TO JOINT VISION 2010

The mission of the Coastal mine hunter (MHC) is to detect, localize, identify, and neutralize current and future threat mines in littoral areas, harbors, and coastal waters worldwide. The MHC is a vital part of dominant maneuver in maritime scenarios, contributing to both strategic and tactical mobility of naval and land forces. The MHC also part of full-dimensional protection, since naval mines inflict personnel and material casualties, as well as deny freedom of action.

The Coastal Minehunter is a conventional displacement monohull constructed of glass-reinforced plastic (GRP). The design is based on the Italian LERICI class of mine hunters. The ship is 188 feet long with a beam of 36 feet and displaces about 895 tons. Non-magnetic diesel engines, similar to those installed in the MCM-1 class, drive cycloidal propellers. Although not previously used in Navy combatants, cycloidal propellers have been used worldwide in ferries, mine sweepers, and tugs. Major machinery platforms are suspended from the main deck to provide acoustic isolation and shock dampening.

The combat system includes the AN/SYQ-13 Navigation, Command, and Control System; the AN/SLQ-48 Mine Neutralization System (MNS); the AN/SQQ-32 Minehunting Sonar; and .50 caliber machine guns.

The 12-ship MHC program and an earlier program to construct 14 Mine Countermeasures Ships (MCM) were initiated to replace mine sweepers (MSO) constructed in the 1950s. Milestone II for the MHC program was in FY87 and authorized the lead ship, USS OSPREY (MHC 51). Milestone IIIA (LRIP) was approved in FY89 for MHC 52 and MHC 53, and continued production was approved at Milestone IIIB in FY90. OSPREY was delivered to the Navy in FY93, and nine additional ships were delivered by the end of FY97. The two remaining ships of the class are expected to deliver prior to the end of CY98.

OPTEVFOR completed OT&E of two of the ship's principal combat systems and found them to be operationally effective and operationally suitable. FOT&E of the AN/SLQ-48 MNS was completed in 1991 onboard USS SENTRY (MCM 3), and OPEVAL of the AN/SQQ-32 (V) sonar was concluded in December 1993 aboard USS AVENGER (MCM 1).

USS OSPREY (MHC 51) completed its Shock Trial in September 1995 at the Underwater Test Facility, Aberdeen Proving Ground, MD. The results of this Shock Trial are addressed in the classified report. Although the MHC 51 Class ship is not under DOT&E LFT&E oversight, the MHC 51 Shock Trial is of special interest because it was the first U. S. Navy Shock Trial on a hull constructed mostly of composite material. It provided an opportunity to study the shock response of a composite hull and assess the effectiveness of shock-isolated-cradle structures in protecting shipboard equipment. It was also the first Shock Trial at a land-based facility.

The Navy has analyzed Shock Trial results to full design level shock conditions in areas where problems occurred and has developed design improvements and executed repairs where appropriate and feasible.

The Navy also completed an analysis of the susceptibility of MHC 51 Class ships to selected sea mines. This study, performed by the Coastal Systems Station, Dahlgren Division, Naval Surface Warfare Center at Panama City, used the Total Mine Simulation System (TMSS) in combination with acoustic and magnetic models based on data collected during MHC 51 DT&E. The analysis provided estimates of the distance at which the MHC is at risk of actuating each of the selected mines as a function of ship speed, mode of operations, and mine depth.

The first operational test of the MHC class (OT-IIIA) commenced 24 March 97 at Naval Surface Warfare Center, Coastal Systems Station, Panama City FL, aboard USS OSPREY (MHC 51). This test was a one month, three phase evolution. Attention was focused on mine hunting, mine neutralization, and navigation precision. Several scenarios were used to provide the operational content of test. Both US and threat practice mines were used, since the MHC must be capable of operating effectively against all naval mines. Operational suitability data was collected over the entire test period.

After completing the first and second phases, addressing navigational accuracy and shallow water minehunting, further testing was suspended. The variable depth minehunting sonar developed a problem, which occurs only when operating in deeper waters. Since OSPREY is the only ship with its particular sonar suite, COMOPTEVFOR discontinued testing on April 11, 1997. After additional planning and discussions on data handling, testing was resumed onboard a ship with a more common installation.

The deep water phase of testing was performed by USS BLACK HAWK (MHC 58), upon the ship's return from a NATO countermine exercise. After a brief grooming period and a repetition of some shallow water minehunting events, the remaining portion of OT-IIIA was executed. This testing was conducted during September 19-October 1,1997. This completes testing required by the TEMP and will be used in BLRIP in FY98.

The Deputy Director, Conventional Systems and members of his staff witnessed several DT events and training evolutions aboard several MHC ships. The Deputy Director was aboard USS OSPREY during the first week of operational testing in March.

The MHC 51 Shock Trial demonstrated the ability of the ship to maintain hull watertight integrity and represents a significant achievement, given that glass reinforced plastic (GRP) hull resistance to underwater shock is a relatively new requirement. Shock isolation of cradle-mounted machinery proved to be effective. Due to the extensive inspection of MHC 51, the final Shock Trial report is not yet completed. Publication is anticipated by 31 December 1997.

Initial impressions of our staff who observed the MHC 51 during testing are favorable. The crew was able to effectively accomplish its mission during operational scenarios. The reliability of the AN/SQQ-32 minehunting sonar will be analyzed for its impact on ship operational suitability. The results of COMOPTEVFOR's evaluation and the DOT&E independent assessment will be published during 1998 and reported in the next annual report.