Excerpt from The Bulletin of the Beach Erosion Board, Vol. 8: April 1, 1954

The original meter with the narrower vanes was almost buoyant in water. Adding width to them, of course, was done at a sacrifice of that buoyancy. It is believed that restoring the original vane size would not materially aid in Obtaining operation at velocities lower than of a foot per second. The vanes had been enlarged in an attempt to gain a higher turning moment, but it appears that the maximum usable area had been reached on the first meter. It should be recognized that the vane shape was decided upon through consideration of geometric factors alone, and that no propeller design theories or practices were employed.

It is pointed out that no provision has been made for indicating the direction of flow on the recording, as was done with the Pegram meter. This was not necessary because the curve of velocity drawn by the recorder is roughly the sine curve, and comparison with the curve shown by a tidal stage recorder located nearby, readily sets the direction of flow. The pattern is repetitive, and changes in direction take place slowly over periods of 2 to 6 hours. Without the directional feature it is possible to use insulators on all vanes to obtain a higher input count to the counter circuit. This is an advantage, particularly at low velocities.

In summary, the Bureau of Reclamation has a current meter which satisfies its present requirements. Though some additional development work might produce an improved design which would operate at lower veloci ties, it contemplates no further effort in that direction.
Figure tidal current meter (development BY bureau OF reclamation)

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