DUE TO WAVES OF VARYING LENGTHS AND HEIGHTS. 79 
DISCUSSION. 
THE PRESIDENT:—Gentlemen, you have heard Paper No. 4, entitled “Stresses on Ves- 
sels of the Great Lakes Due to Wave of Varying Lengths and Heights,’ by Prof. Herbert 
C. Sadler, Member of Council, and Prof. Anders Lindblad, Member. This paper is now 
open for discussion. 
Mr. Davin Arnott, Member:—This is a paper the importance and value of which must 
not be judged by the brevity of the text. Treating as it does of a type of vessel which is 
peculiarly a product of the ingenuity of the Great Lakes shipbuilders and a result of the 
wonderful development in the economic handling of bulk cargoes, the paper cannot fail to 
be of interest to those members of this Society who are naval architects. It is a matter for 
further congratulation that Dr. Sadler and Prof. Lindblad have seen fit to place on record 
in our Transactions the result of at least part of the investigation undertaken in connection 
with the work of the U. S. Load Line Committee. 
In the design of any ship structure it is desirable, if undue waste of material is to be 
avoided, not only to know the maximum load to be carried but the most trying condition as 
to distribution of load and the kind of seas likely to be met with in the particular service for 
which the vessel is intended. Available data with regard to wave formations are unfortu- 
nately not so complete nor reliable as one could wish. We read about ocean waves having 
been encountered of a length five to the mile and of a height 40 to 45 feet, but such waves 
must be very rare indeed. It is extremely interesting therefore to have embodied in this paper 
the results of observations of waves actually encountered on the Great Lakes and to be as- 
sured that a wave 350 feet long and 20 feet high is the worst that we need consider. That 
the waves observed were relatively higher than ocean waves is what one would anticipate in 
view of the comparatively shallow depth of the Great Lakes, and in any determination of a 
suitable minimum freeboard for lake vessels it should be remembered that these short and 
steep waves are the most likely to break on deck. Ina recent issue of one of the magazines, 
a Captain Buie, who claims to have sailed the Great Lakes for fifty years, stated that a wave 
that rose more than 8 feet above the surface (i. e., 16 feet from hollow to crest) was a 
mighty big wave for the Great Lakes. 
No objection can be taken to the method of attacking the problem of investigating the 
strength of these bulk freighters adopted by the authors of this paper, but I would like to say 
a word regarding the conclusion, i. e., “That it appears that the lake freighters of today are 
for their service as strong if not stronger than similar ocean-going types.”” As a matter of 
fact there are no similar ocean-going types in existence nor, it is safe to say, in contemplation. 
These large, single-deck bulk freighters are a product of very special conditions, one aim in 
design being to obtain the maximum deadweight on a restricted breadth and draught with 
Le 
the result that the proportion of D = 18 as exemplified in the 580-foot vessel is con- 
siderably in excess of any merchant vessel engaged in overseas service. 
Then again, in making any comparison with the strength of ocean-going vessels on the 
basis of the strength formula laid down by the British Freeboard Committee, it must be borne 
If : F 
in mind that the proposed formula for longitudinal strength 7 = f 6 d is very definitely 
