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It is generally assumed that the British antisubmarine warfare effort in World War I was far too slow in getting underway, and that failure to develop adequate antisubmarine tactics in time allowed the U-boats to come too near to success.
It is therefore surprising to find that the Royal Navy developed in the early months of the War, a destroyer- escort designed to hunt submarines. This was the patrol vessel, otherwise known as the P-boat. Although the P-boat bore little resemblance to the DEs, frigates, and sloops of World War II, she was essentially a scaled- down destroyer, with twin screws, turbines, and destroyer-type construction. Furthermore, the main reason for developing the design was the need to release destroyers from antisubmarine patrols.
From the earliest days of World War I, the Director of Naval Construction turned out various sketch designs for patrol craft. One of the earlier experimental ones was a 125-foot Vedette boat, with a 24-knot speed and a hardened steel "can-opener” stem. From this concept others progressed, and finally the Board of Admiralty agreed on a 20-knot, 230-footer somewhat
larger than the Eagle boats later developed by the Navy.
The new patrol vessel was kept as a simple design, so that non-specialist building firms could tender bids. Mild steel was used, but geared turbines were necessary to guarantee a fair turn of speed. To allow great maneuverability, the rudder was large, and the after part of the hull had a pronounced cut-up, the keel curving upward toward its end.
The P-boat was unusual in appearance. The low, slightly turtle-backed deck running aft to the waterline made her look like a large submarine, and the funnel faired into the bridge had a peculiarly modern look. To modern eyes, the low freeboard seems a great drawback, but at the time it was considered an advantage, possibly on the grounds that she would slice through moderately rough seas instead of rolling and pitching. The other obvious advantage of low freeboard was that it made the ship hard to see, a point which carried weight in the design of all pre-1914 torpedo craft.
Twenty-four P-boats were ordered in the spring of 1915 and came into service later that year. All reports of performance were favorable. Although intended for
only 20 knots at 3,800 shaft horsepower, all were capable of 22 knots at 4,000 s.h.p. The chief weakness was the lack of a proper bridge structure; there was merely a canvas-screened platform abaft the gun, and a searchlight platform. Without a charthouse it was impossible to read a dry chart outside the wardroom, and the captain had no place to rest except his own cabin aft.
Vice Admiral R. H. S. Bacon of the Dover Patrol had the reputation of driving his ships and men without regard to the need for sleep or elementary comfort, so it is not surprising to find that he was consistently against recommending improvements in habitability. Despite his opposition, the order was given at the end of 1916 to provide all P-boats with charthouses. By shifting the anchors from the hawsepipcs to recessed beds at the after end of the forecastle, spray interference was much reduced.
The armament reflects the poor state of ASW in 1915: one 4-inch gun, a high-angle 2-pounder, and two 14- inch torpedo tubes. The only other "weapon” was the hardened steel ram bow made of half-inch high-tensile steel, until February 1916, when permission was given to install two D-type depth-charges. It was suggested at the same time that the tubes should be landed, but it was felt that they should be retained in some boats for use against surface vessels. These were the P-boats stationed on the east coast, where there was always the possibility of a German raid, or the more remote possibility of an invasion.
The Admiralty toyed with the idea of increasing the armament by adding another 4-inch gun aft, but Vice Admiral Bacon pointed out that the extra gun would be of no use against enemy destroyers. "As at present designed,” he said, "these boats excellently fulfill a subsidiary purpose in war, and it will be a great pity if their efficiency is compromised by additions which will never usefully be brought into play in war time.”
The Director of Naval Construction made the point that British submarines would soon be capable of 24 knots on the surface (the ill-starred "K” class). If this was matched by new U-boat designs, the P-boats’ comfortable margin of speed would vanish. He then out
lined the practical problems of redesigning the P-boat to meet such a threat. The following changes would have to be made:
Length increased from 230 feet to 245 feet Displacement from 575 tons to 650 tons Shaft h.p. from 4,000 to 6,000 Cost from $408,000 to $520,000
Sir Henry Oliver, Chief of the Naval War Staff, killed the argument with the observation that the only important need was to get P-boats delivered on time, and that a P-boat chased by a destroyer would find a capability of 24 knots as futile as 22.
In 1917, the P-boats were equipped with hydrophones and explosive paravanes, an important improvement in their offensive power, matched by the installation of 30 depth charges in place of the tubes. At the end of 1916, eleven were earmarked for conversion to decoy vessels; this involved building up the superstructure to resemble a small coaster. Originally designated PQ-boats, they were renamed PC-boats to avoid confusion with the "Q” ships. Although it was clear that the decoy technique was yielding diminishing returns, ten more PC-boats were ordered in 1917.
The chief point of interest about the P-boat design is that the Admiralty showed unusual foresight in laying down specialized ASW vessels so early in World War I, before the full potential of the submarine had been realized. What is more, the P-boat was perfectly adequate for her tasks, and needed no drastic modification. By the time of the Armistice, P- and PC-boats had sunk five U-boats, but as any student of ASW knows, success is not measured in terms of submarines sunk. All reports on their handling and steering showed that they performed their duties well.
Although hampered initially by lack of weapons, the P-boat was easily adapted to use the new weapons developed in 1916 and 1917. No more convincing proof of the P-boat’s reputation as a U-boat hunter is needed than the Admiralty’s decision in 1919 to use P31, P38, P4o, and P59 for evaluation of the early sonar devices, and to gain a final contribution from a worthy design.