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Whitby-class frigate
The Type 12 or ''Whitby''-class frigates were a six-ship class of anti-submarine frigates of the Royal Navy that entered service late in the 1950s. They were designed in the early 1950s as first-rate ocean-going convoy escorts, in the light of experience gained during World War II. At this time, the Royal Navy were designing single-role escorts and the ''Whitby''s were designed as fast convoy escorts capable of tackling high-speed submarines. However, this made the ''Whitby''s more expensive and sophisticated to produce in large numbers in the event of a major war, and so the Type 14 "utility" or "second-rate" anti-submarine frigate was developed to complement the Type 12. Although themselves rapidly outdated, the Type 12 proved to be an excellent basis for a series of frigate designs used by the British and Commonwealth navies for the next 20 years.
==Design==
Critical to the design of the Type 12 was the capability to steam for long periods of time in heavy seas, economically and at high speed. For this reason a novel hull form was devised, which despite appearance, was totally unrelated to that of the earlier Type 41 / Type 61 design. The hull showed the fine lines more typical of a destroyer, but had a raised forecastle with considerable flare. The fo'c'sle deck was level to maintain maximum freeboard aft of the stem where it is most likely that waves will break across the deck. These two features meant that the hull not only cut through the water, but that spray was thrown upwards and outwards, away from the bridge and gun turret. This was especially important in high latitudes where war experience had shown that spray could cause rapid and undesirable ice build-up on the forecastle. The deck edges and hull also met at a curve rather than an angle, the anchors were recessed, and protrusions were kept to a minimum to limit the potential sources of ice build-up and spray generation. The Mark 6 gunhouse was large and heavy, so had to be carried low to maintain stability and give a good view over it from the bridge. The forecastle therefore had a very distinctive kink, allowing the position of the guns to be lowered. This had the added benefit of moving the bridge aft, where there was considerably less motion, improving the lot of the watchkeeper. The hull form, coupled with a twin-shaft double-reduction geared steam turbine plant (the Y-100) that operated at high temperature and pressure (for efficiency) and low revolutions, with new five-bladed low-cavitation propellers (for efficiency and quietness) lent themselves to the perfect hull for a high-speed, all-weather anti-submarine vessel.
Experience with the Type 15 frigate program, rebuilding wartime destroyers into fast anti-submarine frigates had led to the adoption of a bridge design characteristic of Royal Navy escorts up to the ''Leander'' class of 1969. The covered bridge, where the ship was conned, was located above the operations room where the ship was fought, and there was a small pilot's position located to the front of the bridge, giving the indicative "T" shape when viewed from above. ''Whitby'' was unique in that her bridge face was vertical, her sisters having the windows mounted at an angle to the face, to cut down on internal reflections inside the bridge in low-light. There was also an open navigation bridge located above and behind the enclosed one.
The original funnel was a straight, cylindrical affair that was designed to resist a nuclear blast, but this was prone to down-draughting and did not clear the hot exhaust gasses particularly well. It was replaced by a heightened, raked, streamlined version with a characteristic domed top. This was incorporated in later build vessels, and in all of the subsequent ''Rothesay'' class. Only ''Scarborough'' retained the stubby vertical funnel throughout her career.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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