DUE TO WAVES OF VARYING LENGTHS AND HEIGHTS. 81 
similar concession, the allowable draught would be further increased to 26 feet 6 inches and 
still meet his proposed standard. 
The nearest ocean-going vessels in type and dimensions to the big lake freighters are the 
20,000 dead-weight ton Bethlehem ore boats designed by Mr. Frear, the dimensions being 
550 by 72 by 44 feet and the maximum draught 32 feet. The machinery is located aft, and 
the deck erections consist of a poop and forecastle, also a short navigating bridge which 
does not contribute to the longitudinal strength of the vessel. The proportions of these ves- 
sels are moderate, being in the neighborhood of 12% depths to length, and the longitudinal 
strength is in excess of the freeboard standard for ocean-going vessels of ordinary type. It 
would be interesting to have the statical bending moment diagrams published to compare with 
the data contained in Dr. Sadler’s paper, and perhaps Mr. Frear could be persuaded to read 
a paper on the Bethlehem boats at our next meeting for the benefit of the members of 
this Society. 
REAR ADMIRAL Davin W. Taytor (C. C.), U. S. Navy, Honorary Vice-President :— 
Dr. Sadler is a member of the Load Line Committee, and, as chairman of its Great Lakes 
Sub-Committee, did an enormous amount of work, and I think this Society is to be congratu- 
lated that a small portion of that work will be published in the Transactions of this organiza- 
tion instead of buried in a government report. 
The information with reference to the waves on the Great Lakes is exceptionally valu- 
able, because there is very little information about this subject to be procured as a general 
rule. I had occasion some time ago to try to find out something along that line, and the only 
thing available that I could get hold of was a book published many years ago. It was valua- 
ble, but rather antiquated. 
There is one matter I would like to call attention to, and that is the fact that the waves 
on the lakes have not the characteristics we assume for ocean vessels is not necessarily due 
to the shallow water. The shallow water of the Lakes has probably some influence, but I 
think you will find in every case that, as regards ocean waves, the shorter they are the 
steeper they are. The 250-foot wave would be a great deal steeper than a 500-foot wave. 
The waves formed as a storm sets in and begins to develop, are always shorter and steeper 
on the ocean as well as on the Lakes than the long, low waves after the storm has passed. 
ProFESSOR SADLER:—In answer to Mr. Arnott, I mean, of course, by similar vessels, 
cargo vessels. I was not comparing the cargo vessel with the Leviathan or anything of 
that character. The lake vessels are not built to sail on the ocean. When I said that lake 
vessels were as strong as some ocean-going types, I meant taking it from our standpoint of 
strength. We have usually taken a vessel poised on the crest or in the hollow of a wave 
of her own length, and one-twentieth of that length, in height, as the standard for ocean-going 
types. That is an arbitrary standard, and from that we have established certain arbitrary 
stresses. I know of several ocean-going vessels classed in registry societies where the stress 
exceeds 10 tons per square inch at the top of the shear strake; in no case do the lake vessels 
approach that figure. I think the highest we got was 7.5. That is what I meant by the com- 
parison, showing that we still have a good deal of margin to spare. 
I want to clear up one misconception. I think it is a pity that those who are discussing 
or considering types of vessels designed for special purposes should be continually comparing 
them with ocean-going types. It is not necessary, except so far as information obtained from 
ocean-going types of standard stresses could be made use of and applied. 
