Captain Benton Decker, United States Naval Attaché at Madrid, to Office of Naval Intelligence
Subject: SUGGESTIONS FOR THE PURPOSE OF REDUCING THE RISK OF SUBMARINE ATTACKS ON MERCHANT SHIPS.
Source: NAVAL ATTACHE, Spain, 71, July 13, 1917. O.N.I. 7995 F-6-f
1. The American Consul at Almeria offers the following suggestions for the purpose of reducing the risk of submarine attacks on merchant ships:
2. “I personally interviewed the First Mate of the torpedoed steamer WILBERFORCE, and, according to the information obtained from him and others, it appears that not all possible precautions were taken to avoid the loss of this ship. According to the facts above reported, the steamer before and at the time of the submarine attack was steering almost due west and following in broad daylight the regular course followed by merchant vessels in normal times, being about 25 miles south of Cape Gata when torpedoed. This made it easy for the submarine to get her.
3. “The safer practice, and that which I understand is usually followed by steamers proceeding from Algiers and other ports of the African coast, is to cross the Mediterranean Sea during the night either from Cape Tenes to Cape Palos (Cabo de Palos) or from Oran to Cape Gata (Cabo de Gata), thence steaming in Spanish territorial waters toward Gibraltar. Naturally, in proceeding from Gibraltar to Algiers this course is followed in the opposite direction. As it is possible for even a slow steamer to cross the Mediterranean to and from these points (which are) the shortest distances between the Algerian and Spanish coasts) during the night when the submarine danger [is] much less than during the day, the greatest risk of the journey is thereby reduced to a minimum .
As the ship was torpedoed before the submarine was sighted, I questioned the First Mate as to the lookout. He stated that one of the officers was constantly on the lookout for submarines, but that no more of the crew could be spared for that purpose, as it was only a tramp steamer and they were already short of men. At the time of the attack the Second Mate, who was on the lookout watch, failed to perceive even the periscope.
5. It was the opinion of the First Mate that when a steamer is approaching, the submarine lies in wait for it by remaining completely submerged until the center of the steamer has passed a point slightly forward of the shortest imaginary line between the two vessels (that is, almost directly opposite<)> when the submarine, elevating the periscope above the surface so that accurate aim may be taken, fires the torpedo while still submerged. Thus, the vessel attacked has no warning of the proximity of the submarine until the wake of the torpedo is seen or, as in this case, until the vessel is hit by the torpedo. If, as is believed, the submarine while still completely submerged can by listening (perhaps with the aid of instruments) to the noise of the propellers, ascertain when the steamer is passing the nearest point on the starboard or port side, the periscope would only then have to be lifted above the surface in order to enable the torpedo gunners to take aim.
6. The First Mate stated that it was the habit and tendency of mariners to keep a sharp lookout ahead but not toward those parts of the sea which were then being left behind, and that those on the submarine were cunning enough to take advantage of this habit by waiting until the steamer actually passed the beam before elevating the periscope, so that a very short interval of time elapsed between the appearance of the periscope and the explosion of the torpedo. The Steamer having already passed the submarine, the lookout man still looking ahead failed to observe not only the periscope but also the wake of the torpedo. As it was tea-time on the British steamer, nearly all the crew were below.
7. It is respectfully suggested that the foregoing facts and theories are worthy of study, with the object of improving the methods of lookout on board merchant ships passing through the danger zone, and of formulating stricter or more specific instructions as to the safest course to be followed is proceeding from the African coast to Gibraltar and visa versa.