Free Running Model Turning Tests of the U.S. Coast Guard 47 FT Motor Life Boat.
STEVENS INST OF TECH HOBOKEN NJ DAVIDSON LAB
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Free running, radio-controlled, turning tests were performed on a 19 scale, self-propelled model of the USOG 47 FT Motor Life Boat MLB in order to study the roll characteristics of the boat in turn. Preliminary captive model tests were first carried out on a straight course in a towing tank to calibrate throttle settings and to check rudder effectiveness. Underwater photographs were taken. Little or no ventilation was observed on the rudders. Free running turning tests were then conducted in a maneuvering basin. The model was outfitted with running lights and a visual roll angle display. Overhead photographs were taken and analyzed to obtain trajectory coordinates, and the roll angle, drift angle and heading of the boat as a function of time. Tests were run at scaled speeds corresponding to 10 and 27 knots, rudder angles of 20 and 30 degrees and scaled rudder rates of 5 and 10 degrees per second. Significant differences were measured between the turning parameters at 10 knots and 27 knots. Less significant differences were measured at the two different rudder rates. All results are presented in both tabular and graphical form.
- Marine Engineering