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Hämeenmaa-class minesweepers

Hämeenmaa-class minesweepers, MLC Hämeenmaa and MLC Uusimaa are offshore and icebreaking vessels. In addition to mine clearance, ships are used for maritime security, maritime surveillance and as flagships. The Hämeenmaa class is suitable for international crisis management tasks. They are intended to operate on the high seas and in the archipelago in all conditions. The vessels are used in addition to the minding missions to protect maritime transport, maritime surveillance and management vessels.

There are two ships with naval forces. The ships were modernized between 2006 and 2007, with extensive technical changes and a management system for the whole battle and the main part of The armament was renewed. The vessels are equipped with versatile weapon systems for the omasual. Vessels are suitable for military crisis management tasks. MLC Hämeenmaa (02) belonged to coastal fleet 7 and its home port was in Upinniemi. MLC Uusimaa (05) was ina Coastal Fleet 6 and its home port is located in Turku.

In 1964 Finland purchased two used Riga-class frigates. On May 14, 1964, the former Soviet Navy ships were renamed as part of the re-flagging. Filin got the name Uusimaa and SKR-69 got the name Hämeenmaa. In 1979 Uusimaa was placed in reserve. After major overhaul was made to Hämeenmaa between 1978 and 1979, the vessel was removed from the Navy Vessel List in 1985. These names were subsequently preserved in the othewise unrelated minelayes.

The retirement of the minelayer FNS Keihässalmi in the mid-1990s necessitated the construction of new offshore minelayers. The target was to purchase two mine ships by the mid-1990s. In order to meet the operational and preparedness requirements for mine action, the Navy identified a requirement for two new mine vessels. Mine ship 90 and Mine ship 94 became the working names.

Several operational requirements were set for the new mine ship. A mine ship suitable for Finnish conditions should be capable of operating at sea in all weather and lighting conditions and capable of maintaining a speed of approximately 20 knots in average conditions. In addition, the vessel should also be able to operate in winter in the average ice conditions along the coast. If necessary, the mine ship must be able to lower its mines under threat, which is why the ship must be equipped with adequate self-defense weaponry, especially for airborne threats. In addition to effective weaponry, there was passive protection of the ship, including its radar reflection, IR radiation, magnetic and acoustic properties, to the highest possible standard. In addition to mine action, the mine ship must also be equipped with sufficient preparedness for some other maritime defense tasks. The ship should be of such a maritime nature that it would also be suitable for the long-term security of territorial integrity in the sea area.

The basic technical design of the ship type began already in the first half of the 1980s. The end result was the definition of technical design criteria in April 1985. The original aim was to be a simplified and simple mine-layer. However, the cost / benefit analysis had led it to be now required for other tasks in order to improve the utilization rate of the vessel. The most important of these were suitability for submarine propulsion, certain sea transport, and limited mother ship and command ship duties. The operating environment was required in all weather conditions, including during the winter. The latter required the vessel to be capable of ice-breaking.

However, at this stage, the financial conditions for the acquisition were not met. Priority was given to the construction of a second missile fleet (Rauma class) in the overall development of the Navy. The acquisition could eventually be included in the 1989 revenue and expenditure estimate as part of the Navy's specialty material ordering mandate for the year The acquisition of another vessel was still in the mid-1990s. The operational and technical objectives to be achieved for the procurement were specified in April 1988 and presented to the Command of the Armed Forces.

In addition to the acquisition of the ship itself, the Mine Order procurement mandate included its weapon systems and special communications and electrotechnical equipment. The technical preparation of the acquisition was carried out in such a way that contracts for various sub-contracts could be concluded as early as spring 1989. However, the contract itself proved to be more complex than expected. On the basis of the T3 tender, the contract was negotiated with Wärtsilä Oy Meriteollisuus.

However, the acquisition presentation stopped due to the bankruptcy of the company, and as a result, the acquisition was transferred to the second competitor, Hollming Oy, which also built Rauma-class missile boats for a while. The transfer was comparatively legally and technically difficult. This involved, among other things, the redemption of the already completed design material (including the results of model tests) to the bankruptcy estate and transfer to Hollming Oy. The contract between the Ministry of Defense and Hollming Oy was finally concluded. The upheavals in the Finnish shipbuilding industry and the boom in shipbuilding had put Hollming Oy in a difficult employment situation. The company's contact with the then Holker government in December 1990, after some steps, led to the purchase of Minesweeper 94 being optionally funded from the 1991 Supplementary Budget. The contract was awarded to build the vessels, taking advantage of sister shipbuilding, and to develop the naval mining capability faster than expected.

Unlike missile ship acquisitions, it was decided from the outset that minesweeper procurement would be based on the Navy's normal line organization. This decision has subsequently proved to be correct. As with typical military wartime procurement, there were also three main areas for minesweeper procurement: ship (shipyard) procurement, weapon systems procurement, and specialized telecommunications and electrotechnical equipment. in the project group that was in charge of the ship department, which was mainly because that, in terms of implementation, system procurement is sub-contracting with respect to ship procurement. In this case, the purchase of the vessels was also by far the most expensive of the subcontracting.

Although the new mine ship is approximately 3 m shorter than Ostrobothnia, its mine capacity has been increased by modifying in addition to stern and side gates, now also a bow flap. Particular attention has been paid to the mine loading platform and it has been possible to substantially reduce loading time so that the efficiency of the mechanical mine transfer system can now be better utilized. Mine mine equipment operates semi-automatically as in Ostrobothnia, but simpler and more reliable solutions had been achieved in technical implementation.

The strong advances in electronics and computer technology over the last ten years have made it possible to implement a mine clearance planning, command and registration system that is sure to be of the highest standard in its kind worldwide. The development of diesel engines used in Ostrobothnia by about 25% more efficiently made it possible to set the speed target to 20 knots and to raise the icebreaking capacity to 40 cm solid ice. However, the contract speed was 19 knots because the available opposition information was not reliable enough for the modified chassis. Ice frost calculations, in turn, required an increase in the propeller system dimensions to meet the ice class rules. The already selected Ulstein as a propeller supplier changed to Kamewa as a result of the construction yard change Specific design objectives Compared to Ostrobothnia, the hull of the new vessel was mainly modified to improve the sea characteristics.

Already proven in rocket boats in the Rauma class, the design of deck structures and the upper edge of the hull from tilted shallow planar surfaces to scatter radar beams, avoiding radar docks in structures and deck equipment; and coating radar masts with radar absorbent plates. Minimization of other excitations caused by the vessel was also highlighted in the design. Alternatively, the exhaust gases from the engines can be blown under or over water to reduce thermal excitement. The protective jet piping allows the outside of the vessel to be cooled to the same temperature as the sea water surrounding the vessel. In the event of encroachment, the vessel can be deployed with masking nets which, in addition to optical protection, improve radar and infrared protection. In addition, the ship has been equipped with radar alarms and bayonet launchers. In order to navigate mined areas, design objectives also included minimizing underwater noise and magnetism from the ship. body, reduction of noise from propulsion and propulsion has probably caused the most headaches during the acceptance tests, and satisfactory results have only been obtained at the end of the warranty period.

The vessel is equipped with a magnetic protective device, which was designed on the basis of a model study conducted by the Naval Research Institute, which, according to its objectives, reduces the magnetic interference caused by the vessel by approximately 90%. ABC shielding includes equipment for measuring radioactive fallout and warhead concentrations. In case of danger, the vessel can be overpressurized for a long period of time. The air intake into the living and operating spaces is then sucked through special filters to remove contaminated particles. The decks of the ship can be cleaned of the sedimentation particles by means of the aforementioned shield jet. Compared to our previous battleships, the Rauma class and the Hämeenmaa class are significantly more advanced in their ABC protection. The same applies to fire protection, which has received a lot of attention with the transition to aluminum vessels (Helsinki and Rauma classes). Carefully designed fire compartmentation, fire insulation of structures and minimization of combustible material, including the transition to halogen-free and low-smoke electric cables, provide a significantly improved starting point for the use of active fire-fighting methods.

The armament of the ship was the Swedish SAL 40L made by Bofors ship artillery and the French Mistral anti-aircraft missile with a domestic platform manufactured by Sakko. In addition, two domestic 23mm cannons were installed on the ship so the requirements could be well met using an optronic, English-made fire control system. The most serious alternatives in the final phase of the acquisition were the French Mistral, the Swedish RBS 70 and the English Javelin. The choice ended up with Mistral. In addition, Mistral was the most modern of the systems and was the easiest to install on a domestic platform manufactured by Sako in cooperation with Instrumentointi Oy.

At sea trials, propeller noise was detected at low speeds that was so severe that it affected the operational performance of the ship. The Navy immediately began an extensive investigation into the causes of noise. A new method of measuring hydroacoustic noise was introduced in connection with the study. As a result, a measuring scale was achieved in a matter of days, which would have meant several weeks of work on the traditional measuring track. Once the causes of the problem revealed by pressure side cavitation had been mapped, the development of the propeller blade design with extensive cavitation model tests was initiated in collaboration with the propeller manufacturer (KaMeWa). As a result of the multi-stage development work, a thin-profile, high-rotation blade shape made of stainless steel was chosen. In January 1994, new propeller blades were installed on the ships for warranty docking, and when the engine speed of the main engines was still dropping, the sea tests proved that the targets were achieved. Harmful pressure side cavitation had been brought under control.

The poor handling characteristics of the Hämeenmaa propellers due to the outward rotation direction, eg in mooring, force the driver to rely mainly on mooring and unmounting methods for handling single-propeller vessels. On the other hand, outboard rotating propellers have very good icebreaking properties. The ship-class mine clearance system has proven to be extremely useful and functional. The unified mine deck solution has 20% more mine capacity than Ostrobothnia. The versatile loading options, short lifts and the use of a mechanical mine transfer system speed up the loading of mines by one third compared to Ostrobothnia. The higher position of the mine deck above sea level and the structural design of the stern of the mine deck allow the mines to land under the most demanding surf conditions.

One of the design criteria for the Hämeenmaa-Iuokka was to improve mine loading. The aim was to both speed up loading and thus reduce the ship's exposure to enemy activities during loading and better support the use of mechanical material handling equipment during loading. Based on these objectives, a working machine-operated mine clearance system was developed to enhance the effectiveness of mine clearance within the ship. The effort of personnel involved in cargo handling within the ship has been significantly facilitated, thus enabling efficient loading in these areas. The key issue for loading time is the time taken from the transfer of mines from storage to ship. Recent developments have led to a very limited number of storekeepers available for mine clearance. This situation is particularly emphasized in the case of capacity building, whereby only personnel already employed in peacetime are deployed.

Due to the personnel situation, the transfer of mines is mainly carried out mechanically. This solution has been strongly influenced by the increased size and weight of new mine models. In a rapidly evolving situation, it is no longer possible to advance mine-loaded mines to or near the quay. In such a situation, the mines are brought directly from storage to the ship. Experimentally, it has been shown that various mine interventions; landings, re-attachments to lifting equipment, etc., multiply the time needed to transport an individual mine by direct transport (from storage to ship).

The structure of the Hämeemna class loading equipment enables the mines to be loaded directly onto the ship via both the stern and bow gate. Of course, the ship's loading equipment also enables conventional crane loading via both aft and side ports. The effective use of the class loading system requires that the platform used be suitable for loading ramps.