Pacific Northwest Section, SNAME, Holds Annual Meeting In Union, Washington

The Annual Meeting of the Pacific Northwest Section of The Society of Naval Architects and Marine Engineers was held at the Alderbrook Inn, Union, Wash., during the weekend of October 13- 15, 1978. The meeting was attended by more than 100 members and guests.

Friday evening's informal buffet provided an opportunity to renew old acquaintances.

Saturday's session began with a short business meeting conducted by president Paul Zankich.

Following the business meeting, two technical papers were presented.

The authors were introduced by Bob Van Slyke, chairman of the Papers Committee.

The first paper, "Shaft Alignment Methods with Strain Gages and Load Cells," was prepared and presented by Robert B. Grant of Diehl and Lundgaard, Incorporated.

Everyone involved in shipbuilding is very much aware of the need for accurate shaft alignment and the traditional methods of insuring alignment. These procedures can be very difficult and timeconsuming on larger vessels. The paper presents improved methods for assuring shaft alignment.

The author specifically examines the use of load cells incorporated into a jacking mechanism, either under the bearings or in place of the bearing shells. An alternative moment method of shaft alignment is also explained. This method offers several advantages over the jack-checking procedure where conditions aboard the vessel dictate its use.

In the end, the method used to align the shaft will be determined by the direct cost associated with each procedure and the availability of measuring instruments.

The second paper, "Vibrations —Some Other Aspects," was written by L. Coward and Dr. R.J.

Savage of Savage and Heierli- Canada, a division of CCS Marine Associates Ltd. The paper was presented by Mr. Coward.

This paper describes several ways in which resonant vibration analysis under controlled circumstances can become a useful tool for information acquisition and system analysis. Of particular interest are the applications of this technique in structural monitoring and problem diagnosis.

The vibration analysis technique is based on the fact that every structure has its own characteristic "vibration signature." Using a number of accelerometers placed on the structure and vibration generators, this "vibration signature" can be determined for the structure. If these measurements are repeated at a later time, any deterioration of the structure will be recorded in the vibration signature measured at that time.

Using this analysis technique, fine resolution in detecting initial failures, such as hairline cracks, is possible. Left uncorrected, these initial failures may develop into a more serious structural failure.

A question and answer period followed presentation of the papers.

In the evening, a banquet was held at the Alderbrook Inn. Prof.

Francis Ogilvie, chairman of the Naval Architecture Department at the University of Michigan, was the featured speaker. He discussed the current state of the Naval Architecture Department at Michigan.

Copies of the technical papers can be obtained from the Section Librarian, C.S. Bracken, P.O. Box 24382, Seattle, Wash. 98124, for a nominal fee.

Other stories from December 1978 issue

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