Historical information

A Ship's Log looked very similar to a torpedo but was used to measure the speed of a ship. When dragged behind the vessel, movement of water past the propeller caused it to rotate, turning the small needle dials to record the distance and speed travelled.
https://museumsvictoria.com.au/immigrationmuseum/resources/journeys-to-australia/

Physical description

Ship's Log Display Head

Inscriptions & markings

Walkers Cherub 111 ships log