Rule 32 – Definitions

PART D – SOUND AND LIGHT SIGNALS
Rule 32 : Definitions

a. The word whistle means any sound signalling appliance capable of producing the prescribed blasts and which complies with the specifications in Annex III to these Regulations.

b. The term short blast means a blast of about one second’s duration.
c. The term prolonged blast means a blast of four to six seconds’ duration.