A ship-log records the distance travelled through the water. With the time in hours between the observations, it gives the ship’s speed in knots. With this log and the speed table also the speed can be determined with this log.

A very nice and complete set with clock, line, rotator, sinker weight, tin with oil, port and starboard shoe in a pine case with labels and instructions for use. There is also a time and knot table, the guarantee certificate, a speed table and an instruction in Swedish about placement and use of the log.
The log is fixed on a shoe at the port or starboard side of the stern. The recorder would have been connected with a line to the rotor at the end of the line. The govenor wheel is fitted in an open end housing. The enamel face with two dials.

The speed variation indicator with slotted outrigger arm is used in combination with a Excelsior IV yacht log as shown. The log has to be attatched to a spindle on top of the indicator. The pull of the line is used as a usefull aid to sail setting during sailing competitions. It hotes changes of speed down to 0,1 knot.

Catalog: NM.3-22
Date: ca. 1950
HWD case:L 14x39x19 cm (5.5×15.3×7.5 in)
Signed: Walker’s Excelsior IV Log and Walker’s “Excelsior” Speed Variation Indicator
Origin: England
Condition: perfect and complete, signs of use