Author: Alexander Malakhoff

Publisher:

Published: 1982

Total Pages: 40

ISBN-13:

The paper concentrates on bow seals because they operate in a more severe environment than do stern seals and have required significantly more development. The need for this was due also to the large increases in size and speed of the SES being considered by the U.S. over existing SES and hovercraft. These increases introduced the need for new designs and/or seal materials to insure that the larger contemplated seal structures would be lightweight and efficiently perform their sealing functions. The paper describes various designs that can be placed in two main categories, Flexible Seals and Semi-Flexible Seals. The former are typified by what are known as bag-and-finger seals as installed on the SES100/B; the latter are typified by the planing seal proposed for the 3000-ton SES. The advantages and disadvantages of these various designs are discussed and a new design based on theory, previous practical experience and laboratory studies is described. This seal called Transversely Supported Membrane; (TSM) Seal is currently undergoing evaluation on a U.S. Navy testcraft. The paper then summarizes the extensive seal materials test and evaluation programs that were undertaken both solely by SESPO and by joint programs with the Navy ACV community. These programs were directed largely towards improving the strength and wear resistance of bag-and-finger materials. Studies of finger motions on the SES100B land on a towing tank test rig indicated that finger tips may experience accelerations in the 6000-8000 g range. The intensity and frequency of these accelerations are related to craft speed, cushion pressure and mass and stiffness of finger material.