From Battle of Jutland Crew Lists Project

Signalman Branch
Rating Description Equivalent
Signal Boy Youths joined as Boys between
15 and 16 and a half.
Signal Boys were trained in shore
Boy 2nd Class
Boy 1st Class
Ordinary Signalman - Ordinary Seaman
Signalman - Able Seaman
Leading Signalman - Leading Seaman
Yeoman of Signals - Petty Officer
Chief Yeoman of Signals - Chief Petty Officer