A comparative study of the heave and pitch motions of, the deep submersible, Alvin and her support catamaran during surface operations

The heaving and pitching motions of ALVIN and her support catamaran are predicted theoretically and experimentally determined at zero speed by model tests. Comparison is made between theory predictions and experimental results for each of the vessels and then the model test results for the two vessels, with ALVIN in the recovery position are compared. The theoretical results were computed by a computer program based on the Korvin-Kroukovsky linear theory of ship motions in conjunction with Grim's added mass and damping coefficients. The experimental work with 1/20 scale models was performed at the M.I.T. ship Model Towing Tank. It is concluded that theory predictions, correlates reasonably well with model test results for the catamaran. Teh comparisons for ALVIN were invalidated by questionable experimental data and possible inapplicability of theory. From experimental tests, it was concluded, that the motions of the two ships are synchronous at wavelengths about equal to the length of the catamaran, that the catamaran significantly damps the heave of ALVIN, and that the ALVIN has little effect on the catamaran, in the recovery position. Recommendations for further research in this important part of a "Deep Submergence Vehicle System" are presented.This work has been carried out under Contract nonr-3484(00), NR 260-107 with the Office of Naval Research