Eventually it will come to the surface, when the bow is pointed up by the strain on the tow-rope; greater the speed the more quickly will it be brought to the surface. In shallow water this should be particularly attended to, as in diving it might strike the bottom and injure the levers; and if the safety key has been withdrawn, explode; moreover it brings an undue strain on the tow-rope. The torpedo can now be gradually veered out to the distance required, the safety-key line so attended, that a sufficient strain is kept on it as not to allow of a long bight of line dragging astern of the torpedo; at the same time having due regard to the strength of the yarn by which the line is stopped to the handle of the torpedo. The distance veered must depend upon the nature of attack. The tow-line should be marked with knots every ten fathoms; under some circumstances the torpedo would be close to the ship until passing the enemy (see [Tactics]); at other times veered to 40 fathoms it will be found most suitable. The full divergence of 45° is obtained up to 50 fathoms, beyond that the bight of the tow-rope in the water drags the torpedo astern unless the tow-rope is triced much higher up, which has its disadvantage; 40 to 50 fathoms of tow-rope gives the best command of the torpedo, veering 2 or 3 fathoms of tow-line suddenly will always sink the torpedo some feet below the surface. Should it become necessary to use the torpedoes with a stern-board they can be so used, but in this case the port torpedo is used on the starboard bow and starboard on the port; all other arrangements being exactly the same. In rough weather, advantage should be taken of the roll, and the torpedo allowed to swing out from the yard, and be let go by the run, checking the tow-rope immediately the torpedo is in the water. It is not absolutely necessary to ease the vessel when launching, the torpedo can be launched at full speed. In the event of its being found necessary to cut adrift the torpedo, in consequence of coming suddenly across a friendly vessel, the tow-rope should be cut near the brake, and if the buoy-rope has been rove through the large stern-ring, the torpedo will sink and be lost, the buoy only remaining. If the buoy-rope has been rove through the small stern-ring, the torpedo will be suspended by the buoy-rope; and should the safety key not have been withdrawn, can be recovered with safety. In the event of wishing to recover it when the buoy-rope has been rove through the large ring, a toggle must be lashed on the tow-rope abaft the leading block on the yard, when it can be recovered by the buoy-rope; as a general rule, it will however be found best to expend the torpedo, and not attempt its recovery. By slacking the tow-rope roundly and stopping the vessel, a friendly ship can pass over the bight of the tow-rope without striking the torpedo; but this is rather a delicate operation, particularly if the safety key has been withdrawn.
Recovering the Torpedo.
Should the safety key have been withdrawn, great caution must be used.
Drawing 5.
Tongs, for going round the upper part of the bolt, to take the place of the safety key, when once clasped and secured round the bolt, render the torpedo safe to handle; this could only be done from a boat. With the safety key in, there is no danger in hooking it inboard again by its own tow-rope, and hoisting up the buoys at the same time with a grapnel.
Torpedo arranged to Explode by Electricity.
To substitute the electrical method of firing the torpedo for the mechanical one, all that will be necessary is to unscrew the priming case from the centre hole of the mechanical torpedo, and screw in the electrical arrangement which contains McEvoy’s patent circuit-closer, especially adapted by him to suit this particular torpedo.