The rotator was connected to the log by a rope 6 ft.
In Thomas Walker's harpoon or frictionless log, introduced in 1861, the wheelwork was enclosed in a cylindrical case of the same diameter as the body of the rotator or fan, and the latter was brought close up to the register, forming a compact machine and avoiding the use of the 6-ft.
Owing to the increased friction produced by a rotator making approximately 900 revolutions per mile, towed at the end of a line varying from 40 fathoms for a 12 -knot FIG.
Speed to 60 fathoms for 20 knots, the pull of the line and rotator is borne by coned rollers, having their outlines tapering to a common point in their rotation, thus giving a broad rolling surface.
4 the shoe H is secured to the taffrail, and the rotator in the water is hooked to the eye of the spindle M by the hook D.
When not in use, the register is removed from the shoe by lifting a small screw button near C. The tow line is usually plaited, and to avoid a knot close to the rotator, the latter is secured to the former by a knot inside an egg-shaped shell (fig.
The outer pair receive the strain of the rotator, and the inner are for adjustment and to prevent lateral movement.
The blades of the rotator are adjustable, being fitted into its tube or body by slits and holes and then soldered.
Constant use, increased friction (m o r e especially at high speeds), and damage to the rotator will alter an ascertained log error; head or following seas, strong winds, currents and tidal streams also FIG.