(a) Open fire instantly on any submarine sighted. Don’t delay the first shot even if it is apt to go wild,—it will show the direction of the submarine and will have a pronounced moral effect.
(b) Continue to fire as rapidly as possible. Short shots interfere with the ability of the submarine to see and aim.
(c) If submarine appears less than six points on bow and not more than 2000 yards away, head for submarine at best speed.
(d) If submarine appears more than six points on bow, abeam, or on the quarter, head directly away from submarine at best speed.
(e) If torpedo wake only is seen, fire gun immediately and indicate direction to other ships and manœuvre to avoid torpedo as in case of submarine, i.e.—turning towards torpedo if less than six points.
(f) Other ships of convoy turn from direction of submarine and scatter at best speed, maintaining keenest lookout for torpedo wake and for a possible mate of the attacking submarine.
(g) Resume course when it is deemed that your vessel is outside the danger zone of attacking submarine.
Night Attack:—All vessels instantly change course ninety degrees either to port or starboard. Course will be resumed before any vessel has proceeded ten miles after ninety degrees change. If any vessel is damaged by torpedo, that vessel will act independently and all other vessels of convoy escape at best speed. The damaged vessel may send out radio distress signals provided for merchant vessels.
Owing to the presence of escorting ships it is not probable that submarines will be caught on the surface and therefore will not attempt to use her guns. It is very probable that the first indication of the presence of a submarine will be the wake of her torpedo.
Mines, floating or submerged, may be encountered. All floating objects, the character of which is uncertain, must be carefully avoided. Floating mines have recently been encountered under the following conditions: