The SWATH Mine Hunter

Seawaves Magazine

Navy Leads the Way in Mine Hunting Technology

By Jane Tyler

LUMUT, Malaysia (NWS) -- It is the only one of its kind in the world, and it can deploy in less than three days. Its crew believes it to be one of the best small boats ever built, as it is a forerunner in mine hunting technology.

This unique vessel is the Mine Hunter "SWATH 1" (MHS 1). SWATH, which stands for Small Waterplane Area Twin Hull and is attached to Explosive Ordnance Disposal Mobile Unit 7 in San Diego. Both active duty and Reserve Sailors man it, making it an outstanding platform for Reserve Annual Training (AT).

One of the exercises the SWATH was recently involved in is Cooperation Afloat Readiness and Training (CARAT) 2000. The boat was in Lumut, Malaysia, participating in joint Mine Countermeasures (MCM) exercises with the Royal Malaysian Navy as part of Task Group CARAT 2000. CARAT 2000 is an annual series of bilateral training exercises between US Naval forces and Southeast Asian navies designed to promote interoperability. CARAT is comprised of five phases; each phase of the exercise takes place in a different Southeast Asian country.

The crew of SWATH has been conducting mine-hunting countermeasure exercises and during the Thailand phase, several Reservists participated in the combined exercise with the host nation.

Electrician's Mate 1st Class (SW) Derrick Thomas from Lafayette, La., is the craftmaster for the SWATH. "This is the only one of its kind in the Navy. This vessel is unlike the other mine-hunters or minesweepers in that it can be deployed to any region of the world in three to five days."

"We can transport the SWATH via 15-ton Marine truck, C-5 airplane, and by ship. Air, land, or sea, we can go anywhere," added EN1 Harold Stevens, of New York City, the chief engineer for the ship. "Filipino and Thai officers and crews have embarked on our ship to train on mine countermeasures. We provide them with information, conduct 'Q-route' surveys, and training and assistance in MCM operations."

A Q-route survey is the seeking of mines in different quadrants, dividing the sea-lanes into four boxes. The crew's success in MCM operations is due in part to the sophisticated instruments on board the SWATH. The two primary instruments, designed to search and locate potential mines, are the Klein 5500 Multi-beam Side Scan Sonar and the Deep Ocean Engineering Phantom HD 2+2 Remote Operated Vehicle (ROV).

Electrician's Mate 1st Class Ray Cole, responsible for conducting the sonar scans and analyzing the data, said, "The Klein side-scan sonar consists of five sonar beams that can make a detailed bottom map 300 meters (990 feet) wide. With it, we can track six objects at the same time. If it finds an unknown object, then we send in the ROV, which contains a video camera on board to take a closer look and send back a higher resolution image for marking."

This was crucial during a recent assignment as a support vessel during the salvaging operations of Alaska Airlines Flight 261 earlier this year.

Another piece of equipment vital to the safety of the SWATH is the Simrad SM2000 forward-looking sonar, which scans for mines up to 300 meters ahead of the craft.

"We can make smaller course turns than most mine hunters, which is essential to get into tight areas where mines may be located," said Cole.

Exercises such as CARAT offer excellent training opportunities for US Navy personnel and their Southeast Asian military counterparts. The SWATH has time and time again proven to be an excellent mine hunter craft.

During Exercise Kernel Blitz in 1999, SWATH made 30 contacts, with 10 of the contacts identified as potential mines. Of the 10 mines identified, seven of the mines were on the bottom.

Another advantage of the craft is the stability. Its four computer-controlled planes act in conjunction to keep the craft to only two degrees of roll, even in 10 to 14 foot seas.

"Its design makes the craft stable during rough seas, which is ultimately beneficial for the crew. We don't have to deal with as much seasickness and fatigue," commented Thomas.

Saturday, 23 September 2000

Copyright 2000 Seawaves Publishing Ltd


The SWATH Mine Hunter:
An enabling technology that works

James M. McCoy, CAPT, USNR (Ret)
LCDR Wayne Neely, USNR (TAR)

Paper to be presented at
Fourth International Symposium on Technology and the Mine Problem
Naval Postgraduate School
12-16 March 2000


The procurement of MHS-1 was originated in early 1995 by Commander, Mine Search Squadron, Corpus Christi, Texas. This Reserve command was created in 1994 as a replacement for the Craft of Opportunity (COOP) Squadrons, with a newly defined mission in support of the Navy’s Expeditionary Warfare Role. Functionally, this mission consisted of underwater searches and associated tasks, employing Commercial Off-the-Shelf Technology (COTS) to support the Navy’s Mine Countermeasures mission in the littoral environment.

The Required Operational Capability and Projected Operational Environment for the Mine Search Squadron required a small craft with the following capabilities:

While researching suitable craft, none of the existing U.S. Navy small craft fulfilled the requirements. At the time, the Navy’s seakeeping requirement for all newly developed small craft, such as the MK V Special Operations Craft (SOC), the Inshore Boat Unit (IBU) craft, and the Marine Corps 51 foot PCF focused on seakeeping capabilities at high speed. These acquisition programs were relatively unconcerned with platform stability at extremely slow speeds, which is required for the minehunting mission (such as 3-5 knot tow speed for a single-beam side scan sonar and the bare steerageway required for operation of a Remotely Operated Vehicle (ROV)).

To satisfy this slow speed seakeeping requirement, SWATH technology, which is inherently stable regardless of vessel speed through the water or the direction of the seas, was being utilized to satisfy similar slow speed seakeeping requirements. At the time there were approximately 50 craft of the SWATH design being utilized throughout the world for tasks such as pilot vessels, diving tenders, ocean research vessels, and other tasks of a highly specialized nature. In addition, a SWATH design for a small underwater search vessel was supported by two previous unrelated studies.

A study by the Naval Studies Board, "Mine Countermeasures Technology, Volume IV, The SWATH as an MCM Platform," presented a design for a 22-ton SWATH mine countermeasures vessel. Coincidentally, a report produced for the National Oceanic & Atmospheric Administration (NOAA), dated 9 December 1994, recommended a 42 foot SWATH design as a "Fast-Transit" Hydrographic Survey Launch, as part of NOAA’s Fleet Replacement and Modernization Program. With concurrence from Commander, Mine Warfare Command (COMINEWARCOM) and the Commander in Chief Atlantic Fleet (CINCLANTFLT) a decision was made to pursue the construction of a prototype SWATH vessel for the Mine Search Squadron using FY 94 National Guard and Reserve Equipment (NG&RE) funds designated for the purpose.

The Office of Special Technology (OST) reports directly to the Offices of the Secretary of Defense (OSD). Contained in OST’s charter is the authority to rapidly procure prototype systems. As such, OST was assigned responsibility by the Resource Sponsor, CNO (N-85), as the Equipment Program Manager to oversee the SWATH procurement for Commander, Mine Search Squadron. The methodology employed by OST consisted of a market survey of commercial SWATH builders to determine to what extent the commercial shipbuilding industry could support the project. A Broad Agency Announcement (BAA) was issued in the Commerce Business Daily (CBD) in January 1996 to determine industry interest. Limited open competition amongst qualified bidders was initiated by OST in June 1996 and, in the fall of 1996, Swath Ocean Systems, (SOS), San Diego was selected as the successful bidder. Management of the procurement was exercised through Battelle Institute on a delivery order contract.

Specifications for the solicitation had been prepared jointly by Commander, Mine Search Squadron and the Naval Surface Warfare Center, Carderock Division, Detachment Norfolk, (working directly for OST). These specifications called for construction of the vessel using a proven design, modified to fit the Navy’s requirements, employing "best commercial practices" and built to recognized standards established by such organizations as the U.S. Coast Guard (USCG) or American Bureau of Shipping (ABS). COTS electronics were provided by Commander, Mine Search Squadron as Government Furnished Equipment (GFE). Naval Sea Systems Command (NAVSEA) engineers were consulted. Construction commenced on 15 January 1997 and SWATH was delivered to the Navy in the spring of 1998. The end result of this procurement effort was the Navy’s first, true open-ocean minehunting/underwater search capability in a small craft. The final craft was designated Mine Hunter SWATH, One (MHS-1). The significant features of the completed craft include the following:

In late 1997, prior to delivery of the SWATH vessel to the Navy, a decision was made to disestablish Commander, Mine Search Squadron and convert four subordinate Mine Search Units to Inshore Boat Units (IBUs), reporting directly to Commander, Naval Reserve Surface Force, New Orleans. This decision was prompted by budget constraints and coincided with a decision to realign the Naval Reserve’s Naval Coastal Warfare capabilities. Accordingly in February 1998, MHS-1 was transferred to Explosive Ordnance Disposal Mobile Unit SEVEN (EODMU SEVEN). The decision to transfer MHS-1 to EODMU SEVEN was made due to the significant similarities of the mission of EOD Area Search Detachments (ASD) and that of the Mine Search Squadron. Specifically, the rationale included:

MHS-1 SWATH Technology Advantages

There are a large number of technological advantages that MHS-1 offers due to its SWATH design, compactness, flexibility, and deployability. An understanding of these advantages is key to the employment of MHS-1 to its maximum benefit. . Following is a discussion of these advantages.

The SWATH hull-form is an enabling technology. Without it, the following concepts are unachievable:


There are a number of specific advantages of MHS-1 due primarily to its SWATH hull form design.

To maximize its flexibility to provide a rapid mine countermeasures response anywhere in the world, MHS-1 was designed to be readily air-transportable. Specific actions taken during the design process to ensure this capability were as follows:

As a secondary means of transport, consideration during the design process was given to the requirements for sea transport of the vessel. Specific design considerations included the following:

To fully appreciate the advantages of the SWATH hull form for the specified mission areas, it is beneficial to make a comparison of the SWATH form to a monohull vessel of a similar size, that might be utilized for this same purpose. Following is a summary of this comparison:

MHS-1 is not presently configured with any "military" mine warfare equipment (other than a P-coded PLGR GPS). The concept around which it was designed and which has been executed demonstrates the exploitation of readily available, commercial-off-the-shelf (COTS) technology. A system upgrade was performed in 1999, replacing the COTS single-beam side scan sonar with a high-speed multi-beam system and adding a forward scanning obstacle avoidance sonar (OAS) and upgraded acoustic data collection, analysis, and logging systems. The current equipment configuration includes the following systems:

MHS-1 as presently configured, is a manned vessel, although it is amenable to modifications to support remote control or programmed remote operations. This feature would provide significant benefits under certain scenarios. The vessel depends on passive means for quieting and reducing magnetic signature. Active enhancements in these areas are yet to be included. These considerations dictate risk management as an operational consideration until technology is added during upgrade.

Exercise Summary

Since its construction and transfer to EODMU SEVEN, MHS-1 has participated in several exercises having an MCM component to them. The results from these exercises provide valuable insight into the potential capabilities and employment of MHS-1.

This exercise was conducted in Puget Sound, under a Port Security/Harbor Defense scenario. MHS-1 was the only MCM asset in the exercise and was lifted to the exercise onboard USS COMSTOCK (LSD 45). MHS-1 was transported on the flight deck while sitting in its air-deployment cradle. Loaded in this manner, the cradle provided a more secure means of tie down for MHS-1 and protected the pontoons from having their paint damaged. MHS-1 was employed prior to actual exercise play to perform a simulated Q-Route survey mission. Significant exercise results included, the following:

This exercise was conducted in the Camp Pendleton operating area. Since no other SMCM assets were available, MHS-1, de facto, fulfilled the surface role in the MCM Triad. AMCM support and command and control were provided by USS BONHOMME RICHARD (LHD 6). MHS-1 transited from San Diego to the exercise area and worked from a shore base to support exercise requirements, utilizing the EDGETECH DF-1000 single-beam side scan sonar. MHS-1 was tasked aggressively by COMCMRON THREE, really testing its capabilities, by exceeding designed parameters for seas state and endurance. One exercise observer noted that "MHS-1 was doing everything the MCM ships would have been doing." Significant exercise results included:

This exercise was conducted in Korea, with movement to the exercise provided via commercial container ship. MHS-1 had undergone an equipment upgrade, including the Klein 5500 system, prior to the exercise and was employed in a variety of MCM roles, including Q-route surveys and Clearance operations. MHS-1 worked for the Harbor Defense Commander and the MCM Commander (COMCMRON ONE) at various times. Significant exercise results included the following:

COMCMRON ONE comments from FOAL EAGLE 99 lessons learned message (CTG 76.8 052359Z NOV 99):

Observation: SWATH/KLIEN 5000 asset made a positive impact on the MCM problem, both in the exercise, but also in Q-route survey.

Discussion: SWATH demonstrated excellent sea-keeping traits, operating in seas that forced some MCM assets to port. The KLEIN 5000 data was analyzed near real time and added significant value in determining bottom type/hunting conditions and finding exercise mine shapes. It produces very high quality data that was easily rendered in useful form by NAVOCEANOs bottom mapping program.

Recommendation: R1 – Continue to evaluate SWATH platform R 2 – Continue to evaluate KLEIN 5000 R3 – Employ SWATH/5000 for ROK route surveys when AMCM cannot be budgeted into this AOR. R4 – Consider employing KLEIN 5000 on regular route survey ops.

Projected Operational Employment

Following is a discussion of the projected operational employment of MHS-1.

Following are some considerations with respect to the base of operations for MHS-1.

This method was anticipated to be one of the primary options when the small SWATH minehunting vessel concept was first conceived. For this reason, MHS-1 was designed to be self-sufficient while working in the operating area, but dependent on support from a shore base for all its other needs. Some of this support may be provided by other elements of EODMU SEVEN, which may deploy with MHS-1 and the ASD or by MIUW elements that might be co-located in the area. Some design features that anticipated this employment include:

This method was considered to be a secondary option for MHS-1 employment and was demonstrated during Exercise SEAHAWK 98 to be feasible from a physical standpoint. The difficulty in counting on this option is the commitment already made in deck space to equipment of the embarked Marine Expeditionary Units (MEU) that is anticipated to be part of the expeditionary force. It is conceivable that space may be available onboard an Amphibious platform for transport to theater, but other arrangements are needed to support MHS-1, once in theater.

A commercial vessel or barge may be leased to support MHS-1. This support may be limited to mooring alongside and supporting the vessel from a maintenance, logistics, and habitability standpoint, or may include actually lifting MHS-1 onboard each day, if the vessel size and lifting capability were to support this approach. This option is not without precedent. During operations Earnest Will, two commercial re-supply vessels, MV HUNTER and MV STRIKER were leased to provide a limited minesweeping capability and later on one of these vessels served as a mother ship to several EOD MCM detachments working in theater. Also, the commercial barge HERCULES supported a number of surveillance assets, such as PB MK III vessels that were lifted onboard each day and minesweeping boats (MSBs) from MINEDIV 125.

Though it would impact its ability to conduct AMCM operations, MHS-1 could be carried on deck and supported by INCHON.

A number of SWATH vessels, such as MHS-1, could be supported from a vessel specifically converted to support offboard MCM assets. Besides MHS-1, these offboard assets could include MCM-configured CH-60 helicopters and Remote Minehunting Systems (RMS) that are designated to be part of the organic MCM suite.

A future MCM vessel could carry a number of SWATH vessels and offboard MCM assets discussed above

The initial seven "showcase" organic systems are under development and the Concept of Operations for their use has recently been drafted. This document is currently under review at all levels of command and discussions taking place as to its validity. In this CONOPS, "organic" systems are referred to as "assigned" and the present "dedicated" force is referred to as "supporting. Since the concepts presented in this CONOPS are in their early stages of development, it is premature to speculate what role MHS-1 will play in directly supporting the CVBG and ARG, within the context of this concept

One should bear in mind that the designations organic, dedicated, etc. discussed above only applies when MCM forces are operating in support of a CVBG or ARG. Under many scenarios MCM forces will operate independently to achieve a mission, not directly tied to those of the CVBG and ARG, in which case the ASD may report directly to the theater Navy Component Commander or a subordinate command such as the Harbor Defense Commander. When combined with the other assets of the NRF mobile unit, MHS-1 becomes a complete system with full mine neutralization capability, especially in the shallow and very shallow water regions. As such, MHS-1 can play a dominant role in some of these independent missions, a list of which follows:

There are a variety of search missions in the Inshore area, such as those discussed above. To maximize its usefulness, MHS-1 should remain within its limitations and restrict its operations to the Inshore area. In particular, MHS-1 should operate in the Very Shallow Water (VSW) and Shallow Water (SW) regions within this area. Although MHS-1 is not precluded from operating in deeper water, the primary mission areas will typically be assigned to other forces, such as the MCM-1 and MHC-51 mine countermeasures vessels and to other assets for survey/salvage missions. If assigned to deeper waters, MHS-1 must, of necessity, confine its operations to survey operations. It does not have the capability to neutralize mines (with assigned divers) in deep waters and its ROV is limited in depth by its umbilical to 180-220 ft and does not have a neutralization capability. To ensure adequate support, MHS-1 needs to operate in close proximity to its support base or mother ship.

MHS-1 may also operate in an integrated fashion with other MCM forces. When conducting integrated MCM operations, each member of the team should "play to its strength," performing tasks which it can perform most capably. In this regard, following are some considerations on MHS-1 employment in integrated MCM operations.

Supporting the defense of harbors and their approaches is an ideal notional assignment for ASD and MHS-1. The new organic MCM systems are being developed solely for the purpose of supporting the ARG and the CVBG. Other dedicated MCM forces are closely tied to supporting these Groups as well. All workups, deployments, and exercise support for these units are conducted along these lines. This leaves a gap as to which assets will provide MCM protection in defense of harbors and harbor approaches, two very vulnerable yet vital areas. MHS-1 is the prime candidate to fulfill this role.

After the initial assault and cessation of hostilities in the immediate area of the landing, the ARG may move on to a new landing area, but logistics may continue to flow over the newly established beachhead. To support these logistics operations, additional clearance operations and mine countermeasures may be required. These operations may include widening of the boat lanes, opening of adjacent harbors, clearance of additional maneuver area, surveys of the approaches to the logistics offload areas for mines, as well as both manmade and natural obstacles and obstructions. MHS-1 and the ASD are ideally suited for these tasks.

MHS-1 may be utilized independently and in conjunction with the VSW MCM Detachment to support VSW MCM operations. One identified deficiency of the VSW capability is sustainability in the vicinity of the very shallow water area while conducting operations. If the area is sufficiently benign from other threats and/or if adequate protection can be provided against these threats, MHS-1 can be configured as a "mother ship" to perform command and control functions for VSW MCM operations. Also, operating independently MHS-1 may be used to look into the shallows with onboard sonar systems while conducting passes parallel to the beach.

MHS-1 can play a key role in conducting Q-route surveys in several ways: Examining the seafloor and acoustic conditions for the purpose of recommending new routes in better acoustic environments along transit routes (gross surveys); looking for non-mine objects that present a minelike acoustic return for cataloging (detailed surveys); doing "change detection" after commencement of hostilities.

After the cessation of hostilities, ports that were closed due to the conflict may have to be opened to support logistics operations and to restore the economy and infrastructure of the beleaguered country. There may be ordnance and mines in the water. Navigational aides may have been destroyed/damaged. Channels may have silted over. An example of such restoration operations was the clearance of mines and other unexploded ordnance from the Suez Canal and its approaches, by U.S. and allied forces during Operations Nimbus Star and Nimbus Moon in 1974, following one of the Arab-Israeli conflicts. With its shallow navigational draft and superior maneuverability, MHS-1 would be suited to support these operations.

In the currently-followed MCM Concept of Operations, mine countermeasures is a synergistic mix of MCM-focused operations that build upon each other to provide naval forces the capability to counter the mine threat. The four general types of mine countermeasures operations are:

These four mine countermeasure operations build upon each other in a pyramid like manner. Products developed by the mine countermeasure operation preceding it enable

each type of mine countermeasure operation. As tensions increase, mine countermeasure operations will focus a greater level of effort on an increasingly smaller geographic area. In the hierarchy of anti-mine warfare, bottom mapping is the base of the pyramid. It is necessary to collect the environmental data that permits shaping of the battlespace to the advantage of U.S. and allied forces. Bottom maps are mosaics built up from the sonar images from adjacent passes with side scan sonar. NAVOCEANO has been assigned the responsibility to maintain the master database of these bottom maps. In the future, both dedicated and organic systems will input into this database. MHS-1 is an inexpensive option to add to the bottom mapping database. It has systems that are compatible today with this database and should remain compatible with future developments in this area.

Non-MCM missions for MHS-1 can entail both peacetime and wartime scenarios. These missions include the following:

Though developed for mine countermeasures operations, MHS-1 can also support surveillance missions. It’s endurance and superior seakeeping while loitering make it an excellent surveillance platform in a small craft. Additional communications equipment is required however, to optimize its contribution in this area.

To maximize the utility of MHS-1, a view should be taken toward configuring the boat differently for different missions. For example, additional sleeping accommodations may be added to support surveillance missions. The vessel can support surface surveillance as presently configured with its surface search radar. Addition of a data link would enhance this capability. If required, its MIW mission equipment can be removed from present deck and cabin locations and replaced with other equipment to enhance its surveillance capabilities. These might include more powerful surface radar, ESM equipment, communications equipment, small underwater arrays, etc.

The Inshore Boat Units (IBUs) have trailerable boats, armed with light automatic weapons. The mission of the IBUs is to support the Naval Coastal Warfare Commander with small craft, as necessary to conduct the harbor defense/port security mission. MHS-1 could support the Inshore Boat Units by launching of sonar arrays and sonobuoys, vessel board and search, and acting as a command and control platform or radar picket vessel. MHS-1 has the long range, sustainability and open ocean capability that the IBUs lack. Additionally, the IBUs could perform a "shotgun" mission in support of MHS-1, in certain threat environments.

MHS-1 could also be configured to support the Mobile Inshore Undersea Warfare (MIUW) units. MIUW units are tasked with the surface and subsurface surveillance of inshore areas in support of Anti-Surface (ASST) and Anti-Submarine Warfare (ASW), Port Security and Harbor Defense, Mine Countermeasures, Navy Special Warfare and Counter Narcotics Operations. These units may set up surveillance vans at shore locations to conduct their missions, but do not have any significant boat capability. They are generally supported by the IBUs. Some of the missions MHS-1 can perform in support of MIUW include:

To explore these mission areas MHS-1 should work with the IBUs and MIUW when the opportunity presents itself.

MHS-1 is an ideal test platform to support the development of new novel systems. Two of these might be revitalization of the "Catskill" concept and support of MCM (X). To explore these concepts and others, MHS-1 could participate in Fleet Battle Experiments and other such evaluations of emerging concepts.

USS CATSKILL was one of several MCM motherships that existed in the 1960s. These vessels carried a rudimentary helicopter capability to support MCM, the major utility being for aerial surveillance. They also carried a number of MineSweeping Launches (MSLs). The concept failed, primarily due to the poor seakeeping characteristics of the MSLs. SWATH represents the enabling technology to make the Catskill concept viable.

MCM (X) is a concept under study by the Mine Warfare Ship Program Office (PMS 303), under the Program Executive Office (PEO) Mine Warfare, to study options for the mine countermeasure vessel of the future. It is similar to the Catskill concept, except the "mother ship" would have the capability to keep up with the Battle Group or even sprint ahead when required. It represents a "take-along"-dedicated MCM asset to satisfy the requirements for an "organic" MCM capability. The preferred option has a mother ship of a high speed SWATH design carrying a number of AMCM helicopters and SWATH mine countermeasure vessel (MCMVs), similar to MHS-1.

MHS-1 has successfully demonstrated in Fleet exercises that it has excellent seakeeping ability that contributes to improved operator and equipment effectiveness. It has also proven that it is easily deployable via sealift on a variety of platforms and that it has the sea legs to transit independently in the littorals to the assigned area of operations. It is a relatively inexpensive platform equipped with state of the art commercial-off-the-shelf technology that can be effectively operated with 6 to 7 personnel to perform a variety of missions. It’s designed to be airlifted via C-5 aircraft (final Air Force certification is scheduled for April 2000) giving it the quickest response capability from CONUS of any surface MCM asset available. It’s small size and excellent seakeeping ability not only make it a very effective platform for side scan sonar and remotely operated vehicle operations, but also for a variety of other inshore surveillance missions.

MHS-1 in its current configuration packs an impressive capability in a small and rapidly deployable package. While it is an excellent platform for EOD Area Search Detachments mission requirements, as a proven enabling technology it has the potential to be a very powerful tool for the Mine Warfare Force of the future with the following upgrades: active degaussing; pontoon mounted forward looking multi-beam sonar; organic mine neutralization capability; influence sweep capability; remote control /operations capability.

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