A Trainer is the person who, in all but the very smallest guns, controls a gun mounting to the proper bearing for firing, a process called training. Typically, he does this by rotating a hand-wheel or working a hydraulic lever in the case of a large turret. How he establishes the proper training differs when the gun is being locally laid or laid by director.
Station and Equipment
On pedestal mounted guns, the trainer generally was on the right side of the mounting. In a large turret with 2 guns, the trainer would generally sit in a central position. In a pedestal mounting, he would have a geared hand-wheel which would drive the mounting through its training arc. In a large turret, he would use a hydraulic lever or hand-wheel to cause the entire turret to traverse. He would have a sighting telescope or periscope and possibly some data receivers.
When a gun is not being pointed by a director, the trainer looks through a sighting telescope or periscope of some kind and works his training controls to place his cross hairs onto an agreed point of aim on the target. When this is done, he has trained the mount correctly. In small geared mountings, he may endeavour to work his controls to continuously negate the yawing of his ship to keep the cross hairs "on", in a process called continuous aim. Otherwise, he might simply place his cross hairs so the motion of his own ship causes them to sweep through the target periodically and rely on the fact the layer would only press the firing trigger when the training and elevation were simultaneously "on", a process called firing on the roll. In some instances, these strategies would be melded and he might hunt the roll.
When a director was being used, things started to get pretty varied by weapon and service.
British Heavy Turrets
In British capital ships using director fire, the trainer would actually surrender his duty to train the turret to a man on the deck below called the Turret Director Trainer and would occupy himself with assuring that the gun did not fire on an unsafe bearing or when the line of fire was endangered by a friendly vessel. He was equipped with a switch he could throw to break the firing circuits if he noticed some condition which made firing the guns unsafe.[Citation needed]
Small British Guns
In destroyer and flotilla leaders equipped with directors, the trainer would have a Training Receiver to indicate the training angle required from him, and he would work his training hand-wheel to follow-the-pointer on this device. Sporadically, the Sightsetter would call out the current gun range, and the trainer would enter this into his training receiver so that it could apply a Convergence correction for bearing.
German Heavy Turrets
I presume that the regular trainer retained his role in this instance, and used a device similar to the British training receivers to coach him in the proper angle of training.
- Admiralty, Gunnery Branch (1913). Gunnery Drill Book for His Majesty's Fleet. (Book I.) (Instructions for Power-Worked Mountings). London: Eyre and Spottiswoode, Ltd..
- Admiralty, Gunnery Branch (1917). The Director Firing Handbook. O.U. 6125 (late C.B. 1259). Copy No. 322 at The National Archives. ADM 186/227.
- Admiralty, Gunnery Branch (1918). Director Firing For Flotilla Leaders and Destroyers. Pub. No. B.R. 934 (late O.U. 6127 and C.B. 1461 and 1461(A). The National Archives. ADM 186/234.