DPA Projects

General characteristics
Commercial Aspects

Single Role Minehunter (SRMH)

Service - Navy

The Sandown Class Single Role Minehunters (SRMHs) are the latest mine countermeasures vessels (MCMVs) in service with the Royal Navy and are designed to complement the Hunt Class mine countermeasures vessels. As a result of experience gained during the build of the Hunt Class MCMVs, Vosper Thornycroft (UK) Ltd was invited to design the SRMH. The result is the Sandown Class Minehunter of which six are already in service with the Royal Navy and three SRMH variants in service with the Royal Saudi Naval Forces.

Twelve SRMH’s are being delivered to the Royal Navy in two Batches. The last of the five Batch 1 SRMH’s, HMS Bridport, entered naval service in November 1994. In July 1994 a contract was awarded to Vosper Thornycroft (UK) Ltd for the provision of a further seven SRMH and the first of these Batch 2 ships, HMS PENZANCE, entered service in February 1999. The remaining six Batch 2 SRMH’s are currently under construction or undergoing weapon acceptance sea trials. A significant number of design improvements are being introduced into the Batch 2 SRMH’s and are detailed below.

In 1980 the Admiralty Board endorsed a new MCM concept policy. This included a recognition that there was a need to complement the capable but expensive multi-role Hunt Class MCMVs with a cheaper, single-role mine-hunting vessel. The SRMH was designed from the outset as a fully-integrated mine warfare system. However, unlike the Hunt Class it does not have a mine-sweeping capability.

During World War 2, more than 500 Allied and Neutral ships were lost through mines. Since the war, experience has continued to show just how vulnerable shipping is to the mine threat and how essential it is to maintain effective mine countermeasures. Technological advances have been such that sophisticated and costly means are required to deal with the most advanced types of mine.

In times of war, or in support of NATO, the UK therefore needs an MCM fleet capable of maintaining access to Naval Bases, ports and other designated areas. To operate effectively mine countermeasures vessels must have low magnetic and acoustic signatures, good manoeuvrability and high resistance to shock.

General characteristics / technical performance
To allow operations in a minefield, the SRMH’s magnetic signature has been reduced by constructing the 52.5 metre hull from glass-reinforced plastic (GRP) and by the use of low magnetic equipment. Acoustic signature has been reduced by the careful selection and placing of equipment in the ship. Normal running power is provided by diesel engines, but when operating in a minefield the ship runs on slow speed electric drive.

The Ship’s Positioning and Control System (SPCS), provides computer control of the ship’s position allowing the ship accurately to maintain track or to 'hover'. This is achieved through Voith Schnieder cycloidal propulsors used in conjunction with bow thrusters.

The ship is designed around the variable-depth, mine-hunting sonar (sonar 2093) using computer-aided detection and classification. The Naval Autonomous Tactical Information System (NAUTIS M) manages the mine warfare task. Information, including that received from the sonar and navigation system, is displayed in the operations room and bridge.

When a suspected mine is detected, a Remotely Controlled Mine Disposal System (RCMDS 2) is deployed. This system includes a small submersible carrying its own sonar, television cameras and searchlights. The vehicle carries an explosive charge which can be deposited adjacent to the mine. Alternatively the position of the mine can be accurately plotted to enable a safe route through a minefield.

Each ship carries a 30mm gun for self defence but clearly for the SRMH, the role and emphasis remains on clearing a safe path for larger vessels.

The seven Batch 2 SRMH, from HMS Penzance onwards, incorporate a significant number of important design changes to enhance operational capability. These include:

  • Transportable Manned Compression Chamber;
  • tropical operations capability;
  • improved RCMDS recovery measures;
  • improved power train incorporating larger propulsors;
  • new Gemini craft davit;
  • provision of female accommodation;
  • adoption of advanced GRP moulding
  • system in selected areas;
  • introduction of improved combined EMC screening and aerial groundplane.

A full-scale shock trial will be carried out in HMS Pembroke, the second of the Batch 2 ships, to demonstrate fully that all design changes meet the requisite shock requirements.

The 480 tonne SRMH has accommodation for seven officers and 35 crew

Commercial Aspects
The contract for the seven new SRMHs was placed with VT(UK) Ltd in July 1994. The first five vessels are firm priced and the last two are fixed prices.

The SRMHs are being built at VT(UK) Ltd’s Woolston shipyard at Southampton. The jigs and tools required for the build of the SRMH (including the hull mould) are MOD-owned, having been arranged under the SRMH First of Class contract in the late 1980s.

Design changes for the new SRMHs are being managed through a Design Agency contract with VT(UK) Ltd. Alternations & Additions (A & A) guidance information for the in-service SRMH’s is also being managed by VT(UK) Ltd through a Lead Yard Services contract.

Point of Contact - ss224@dpa.mod.uk

>Last Updated - August 1999

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