ABSTRACT
In an effort to explain the apparent ability of dolphins to ride the bow wave of a ship at a speed of 10 knots (Woodcock, 1948) it seemed necessary to show that the animals had weight while immersed. Measurements of the weight of an immersed Stenella plagiodon have been made.‡ First results indicate that a dead animal, which weighs 200 lb. in air, and is 6·5 ft. long, weighs 9·2 lb. when immersed in sea water. This animal, which was in good physical condition, was killed by injection just before the weighings were made.
These measurements were made by Dr Henry Kritzler, associate curator of Marine Studios, Marineland, Florida.
These observations were made by Dr H. Kritzler (l.c.) and W. E. Schevill of the Woods Hole Oceanographic Institution, Woods Hole, Mass.
W. H. Munk of Scripps Institution of Oceanography has said, in a personal communication, that 150 is a reasonable angle to assume for the inclination of the water surface on the advancing face of the larger wind waves. It would be interesting to know the slopes of bow waves of large sea-going vessels.
Durand (1943, p. 132) indicates little change in drag of similar streamline bodies resulting from a small lifting force at low positive angles of attack.
This assumption is based upon Gray’s table which shows turbulent flow beginning at a Reynolds’ number of 5 × 105. More recent experimental work with carefully streamlined bodies has indicated, however, that in some rare cases laminar flow obtains at Reynolds’ numbers as high as 1 ·5 × 107 (see Hill, 1950, p. 216).
