Seakeeping Investigation of the U.S. Coast Guard 270-Ft Medium Endurance Class Cutters: Sea Trials Aboard the USCGC BEAR (WMEC 901)

Two sea trials were conducted aboard the USCG Cutter BEAR to assess the seakeeping performance characteristics of this vessel class. Time correlated ship motion responses, crew performance data, and anti-roll fin stabilizer measurements were obtained. Trial results indicate excessive wetness due to spray as well as substantial crew performance degradation in relatively mild sea conditions. Design and placement of critical ship locations, particularly the pilothouse and communications center, diminished the seakeeping advantages inherent in larger ships. A number of flaws were discovered with the fin stabilization system, including incorrect settings, improper operation, and excessive cavitation. Analytical predictions for the 270-ft cutter which were made and compared to model test data were found to be in generally good agreement. Additionally, computer-generated, irregular sea comparisons between the 270-ft WMEC, a 210-ft WMEC, and a 378-ft WHEC were performed. Results indicate that, in general, the 270-ft WMEC has superior or comparable motion characteristics relative to the 210-ft cutter. Predicted roll for the 270-ft cutter is notably greater than for the 210-ft WMEC. Active fin stabilization, which was not modeled, should reduce roll for the 270-ft vessel to levels at or below those predicted for the 210-ft WMEC. Predicted crew performance degradation substantiates the impact of ship location on critical shipboard functions.