This is the Tri-ang Minic Ships set of US Navy Minesweepers containing models of USS Guardian MCM 5, an Avenger Class Mine Counter Measures Vessel, and USS Acme MSO 508, lead ship of the Acme Class Mine Sweepers.
Acme Class Minesweepers
The Acme class minesweepers built in the mid 1950's were a development of the US Navy's Aggressive class of minesweepers of approximately the same size but built to a modified (improved) design and designated as Mine Division Flag Ships.
The Aggressive / Acme class minesweepers were the largest all-wood warships in the U.S. Navy with a hull designed by Philip L. Rhodes using a hull form that was adapted from the WW2 YMS class minesweepers. The hull design was so strong that the last ships of the basic design, known as the Ability Class, were lengthened from 171 feet to 190 feet. To minimize the magnetic signature of the vessels all of the machinery, fittings and other metal components were made of non-ferrous / non-magnetic materials such as copper, aluminium and stainless steel. They were also fitted with an advanced variable degaussing system which could compensate automatically for variations of the ships position in relation to the earth's magnetic field due to roll and pitch as well as due to course changes.
Originally fitted with UQS-1 minesweeping equipment, which was later upgraded to the AN/SQQ-14 Mine Counter Measures sonar system, they were capable of sweeping for moored / bottom contact, magnetic and acoustic mines. These were among the most complex and innovative ships in the US Navy at that time and at a price of approximately US $ 3.5 million per ship in the 1950's their cost per ton was matched only by the cost of submarines.
The US Navy's mine warfare strategy at this time was designed around a European war scenario which relied heavily on NATO allies to participate substantially in mine warfare operations and an y many of the one hundred Aggressive / Acme class minesweepers were built under the Mutual Defense Assistance Program for transfer to NATO allies including France (15), the Netherlands (6); Portugal (4); Belgium (5); Norway (2); and Italy (4). While most of these vessels have been "paid off" from their original service many of them have been transferred to other navies where they are still in service today.
While two ships of these ships, USS Acme and USS Affray, were decommissioned by the US Navy in the mid-1970s USS Adroit MSO 509 was deployed to the Persian Gulf during the Gulf War in 1991 together with two Aggressive class minesweepers, USS Impervious MSO 449 and USS Leader MSO 490, and the new Avenger class mine counter measures vessel, USS Avenger MCM 1.
Avenger Class Mine Counter Measures Vessels -
The Avenger class mine counter measures vessels are constructed of wood covered with Glass Reinforced Plastic (GRP) sheathing and are the largest US Navy minesweepers built to date as well as being the first minesweepers to be built in the USA for 27 years.
Designed as mine hunter / killers the Avenger class are capable of locating, classifying and destroying both moored and bottom mines of all known and projected types including magnetic, acoustic, and contact mines. Fitted with sophisticated sonar and video systems these ships use precise navigation to map and clear minefields using Remote Operated Vehicles (ROVs), cable cutters, and special mine detonating devices as well as traditional sweeping equipment.
The vital importance of a state-of-the-art mine countermeasures force was highlighted in the Persian Gulf during the eight years of the Iran-Iraq war, and underscored during the Gulf War in 1990 / 1991 when USS Avenger MCM 1 was deployed on mine counter measures operations in company with three 30 year old Aggressive / Acme class minesweepers.
The models are marked on the underside with the Tri-ang Minic logo, "Modern Edition", the model number, and the description "Avenger Class MCMV" or "Acme Class MCMV" respectively.