Tow Tank Results of Bulbous Bow Retrofits on New England Trawler Hulls

摘要

The report describes the research conducted at MIT on bulbous bow retrofits applied to two New England type trawler hulls of 76 and 119 foot overall length. A 4.5' model of each hull was constructed and a series of twelve cylindrical-type bulbous bow retrofits were prepared for each. Calm water model resistance tests were conducted on the bare hull and then with each retrofitted bulb. All tests were done at constant draft, i.e., the bulb configurations were of heavier displacement than the original hull. The calm water results were compared at steaming speeds and a 'best' bulb was selected for seakeeping tests. The bare and bulbous models were then tested in regular waves over a range of wave lengths at both steaming and trawling speeds. Pitch, heave, bow accelerations, and resistance were measured. In the tests, all bulbs were fitted to the maximum limits of the forward draft and were aligned parallel to the waterlines. Variations in bulb diameter and length were studied. The results presented show the effect of these parameters on hull performance.