Rotating Arm Captive Model Tests of the U.S. Coast Guard Prototype 47-FT Motor Lifeboat

摘要

The USCG prototype 47-Fr Motor Lifeboat (MLB) experienced transient roll angles of as much as 40 degrees in a turn at 27 knots with 30 degrees of rudder. The prototype was modified to correct this problem, by moving the rudders to a vertical position, vice 15 degrees outboard angle. The tests reported on here were part of an effort to develop a computer simulation of this snap roll phenomenon. Captive rotating arm tests were conducted using a 1/9.032 scale model of the 47 Fr MLB. The model was fully appended, with the propellers driven by an electric motor. Tests were conducted at two speeds, two turning radii, and a range of drift and roll angles. The results are presented in tabular and graphical form. Curves through the data were drawn using a computer plotting package which did not yield the equations for the curves drawn.