PSMM Mkl/1A is a high-speed patrol ship designed to accomplish a variety of missions. It is a 165-ft aluminum hull powered by six gas turbines driving two controllable reversible pitch propellers. Two-stage combining reduction gears with self-synchronizing clutches enable the ship to operate at speeds to 40 knots on from one to six turbines. Controllable pitch propellers are used to optimize operations in high- or low-speed maneuvers. The propulsion system is controlled by a pair of analog computers which automatically select shaft rpm and propellers pitch based on power command and the number of turbines operating. This paper will discuss the propulsion system and controls as designed, the modifications made during trials of the Mk1 in late 1974, and the improvements made in the Mk 1A and proved during trials in 1977.

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