Comparative Study on the Operability and Safety of 450T Monohull and SWATH Fast Patrol Search and Rescue Vessels

Abstract

A comparative study is performed to explore the operability and safety of 450-tonne displacement Fast Patrol Search and Rescue (FPSR) vessels designed with monohull and SWATH configurations. The first part addresses the peculiar designs of Monohull and SWATH FPSRs. The second part explain about the motion characteristics of the FPSRs in regular waves, followed by the evaluation of their motions in random waves by way of spectral analysis. Results of this analysis are weighted against the seakeeping criteria to examine the operability and safety of FPSRs' operations. In this respect the Monohull-FPSR is capable of conducting general operation above Hs of 3.0 m at V of 0.0 knots and 15.0 knots, but should be limited to 2.49 m when V is 30.0 knots. Helicopter operation should not be conducted when Hs is above 2.0 m, especially at 30.0 knots. General operation on SWATH-FPSR may be performed at Hs above 4.0 m at low and medium speeds, and Hs of 3.21 m at maximum speed of 30.0 knots. Whereas helicopter operation at 0.0. knots and 15.0 knots could be made at Hs slightly lower than 3.0 m, but below 2.0 m when V is 30.0 knots. The aforementioned figures indicate the SWATH-FPSR has a better safety of operation in severe waves than the Monohull-FPSR.