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‘Underkeel Clearance’

Published online by Cambridge University Press:  18 January 2010

J. A. Ewing
J. A. Ewing
Affiliation:
(National Institute of Oceanography)
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I would like to comment on the change in underkeel clearance due to the motion of a ship in a seaway (A. F. Dickson, this Journal, 20, 363).

Captain Dickson, in his conclusions, states that known techniques do not allow underkeel clearance to be calculated when ship motion is present. In fact there are a number of reliable ways of calculating the motions of a ship in waves (for example References (1) and (2), which treat the case of pitch and heave) which may help in this problem. These methods usually assume the ship is in deep water and is heading directly into the waves which are further assumed to be long-crested; but I believe it may also be possible to make reliable calculations for shallow-water effects and for waves which are, in reality, short-crested.

Type
Forum
Information
The Journal of Navigation , Volume 21 , Issue 1 , January 1968 , pp. 91
Copyright
Copyright © The Royal Institute of Navigation 1968

References

REFERENCES

1Korvin-Kroukovsky, B. V. and Jacobs, W. R. (1957). Pitching and heaving motions of a ship in regular waves, Trans. SNAME.Google Scholar
2Grim, O. (1960). A method for a more precise computation of heaving and pitching motions in smooth water and in waves, Third Symposium on Naval Hydrodynamics.Google Scholar
3Ewing, J. A. and Goodrich, G. J. (1967). The influence on ship motions of different wave spectra and of ship length. Trans. RINA.Google Scholar
4Canham, H. J. S., Cartwright, D. E., Goodrich, G. J. and Hogben, N. (1962). Seakeeping trials on O.W.S. Weather Reporter, Trans. RINA.Google Scholar
5Gerritsma, J. and Smith, W. E. (1967). Full-scale destroyer motion measurements, Journal of Ship Research.CrossRefGoogle Scholar