Studies on water movements and sediments in Southern Lake Michigan : part 1[-3] ... / by John C. Ayers.

DISCUSSION

Drogue Sets of 29 October
Care must be taken to use this drogue study for no more than
it is valid for. To command this number of drogues it was necessary to use some drogue floats that were known to be somewhat
effected by wind. These were the floats of drogues 1 through 5.
To contribute toward an assessment of the effect of windage on
these floats, they were set alternately with low-riding lowwindage floats (numbers 6 through 10).
Drogues 3 and 4 moved southward 0.75 and 0.4 miles in 4 hrs
22 min and 4 hrs 33 min, all respectively. At the time of
writing the author is inclined to attribute the 0.4 mile movement of drogue 4 entirely to windage on its float. Perhaps readout of the data from the 30-foot current meter of buoy #20 for
the period 1017 through 1450 will enable a better assessment of
the movement of drogue 4.
Drogue 8 was carried by a low-windage float, and cannot be
denied.
Drogues 6, 7, 8, 9, and 10 were all carried by low-windage -
floats. They tell the essential story of the results, while
drogues 1 through 5 augment the story with detail containing an
incompletely-assessed windage error.
Current velocities indicted by the low-windage drogues were:
#6 0.4 mph southward
#7 0.4 mph southward
#8 0.07 mph northward
#9 0.13 mph southward

8