British P-Boats (1915)

British P-Boats (1915)

United Kingdom (1915-18)
Submarine-chasers, 43 ships

The Mass-built British ww1 sub-chasers
The submarine total war in the Atlantic by 1914-18 was no less savage and critical than in the second world war. With her fleet prisoner of the Baltic and confined to the western cost of Denmark, the German Empire unleashed dozens of U-boats, ranging from coastal UB and UC types to oceanic types capable of roaming the western Atlantic in search for preys.

Fortunately the British Admiralty quickly setup a convoy system and organized an intense shipbuilding program, with a whole range of civilian and naval yards producing patrol boats and gunboats, while trawlers were armed to join the effort. Some of these ships were rather ingenious, like the deadly Q-ships, patrollers in disguise. The P-Boats of 1915 were the most most specialized and arguably, most efficient of all.

Genesis of the P-Boats

P-Boats for “Patrol boats” has been designed in the early days of this submarine warfare by the admiralty to serve as “utility destroyers”.
The admiralty designed a simple ship, enough to be constructed by shipyards that usually built tramp steamers and colliers. As far as 18 were contracted for this task. Therefore there were small difference between ships, mostly delivered in pairs. These small yards were proud of their contribution to the war effort and usually built models.

John Readhead & Sons of South Shields for example, but also Robert Thompson & Sons of Sunderland and R A Bartram & Sons of Sunderland. Those models are now displayed by TWAM’s collections.
They had a particular and odd profile, had a very low profile, were relatively fast (faster than submerged U-boats and surfacing ones) oil-fed boilers and steam turbines, were very agile and well armed to surprise, ram or gun U-boats, and built by a variety of civilian and naval yards all around the country, each building one ship or a pair.

Of the 73 or so planned (P-11 -P-64) only 54 were actually put into service until 1917. A second serie called PC-65 to PC-74 was started in 1918 but saw little service.

Design of the P-Boats

The most striking features for these ships than can best be described as compromises between escort destroyers and smaller ASW chasers, was their very low profile, made to disguise them as submarines, contrary to PC-boats that were Q-ships disguised as civilian coasters and freighters.

Waterline profile of a P-Boat, admiralty builder model in brass and iron, Tyne & Wear Archives & Museums Service 1:48 sloop HMS P23.

This made for early “escort destroyers”, or sloops designed to replace destroyers in coastal operations displaying twin screws and shafts, ram bows of hardened steel, sharply cutaway funnel. Some saw them as an evolution of the late 19th century steam torpedo boats and coastal destroyers. The deck was clean, having only a superstructure covering 1/3 of the hull length at the front. This comprised an elevated platform for the main gun, and the open command bridge behind, more elevated, with a map room and officers square below. Behind was located the radio room and a large and low raked funnel. Behind were located the other gun and the two torpedo tubes at the rear.

Despite their elongated hull they were agile, having a small turning circle. Their machinery, which developed 3,500 shp (2,600 kW) comprised two steam turbines fed by two cylindrical boilers on two screws. Maximum speed as designed was 20 knots (23 mph; 37 km/h) but on trials as noted by builder William Bartram on P26 trials in 21 June 1916, she reached 21.8 knots (40.4 km/h). The small size accommodated Oil fuel tanks only.

The main armament was made of guns. One 4-in gun (102 mm) comfortable enough to deal with destroyers and Germn hochseetorpedoboote, and knock out any submarine caught in the surface before it can dive. But because of its slow rate of fire, there was one 2-pdr (40 mm) ready to pummel the submarine at closer range. This weapon was however more dedicated to AA cover.

No ASW grenades at first as it was then still in development. However the P23 model 1/48 scale (TWCMS: B9663) show two at the rear, port and starboard in cradles.

These P-boats were actually fitted with two 14 in torpedo tubes, placed at the stern deck, and facing aft, port and starboard. According to Conway’s data, P52 was the only one fitted with two 4-in guns, two 2-pdr but no TT at all. The P23 model from Bartam & Sons showed above was only a proposal. The straight bow with a slight ram-like extension (as seen on this model) was considered a weapon, as submarines at that time were relatively slow divers, and when spotted by night or in the fog, there were chances that the ship was over them in a short notice. Plus the shape and size of the rudder and strongly cut up hull aft gave rapid turning, excellent agility.

The P-chasers in service
The serie P11-PP34 were ordered in May 1915, the P35-40 in February 1916, P41-54 in March, P55-62 in April-May, P63 and 64 in June. Of this total ten more (P65-74) were converted on the stocks at PC-Boats (PC-65-74). So the total of hulls was 64 but less were actually completed.

All these ships served with the Dover Patrol, based at Portsmouth, Nore Local Defense Flotilla.

Their details record with submarine kills are yet to be found, but PC56 (renamed and completed as Q-ship) help sinking the U-87 in December 1917. The P13 was renamed P75, and the P38 became the HMS Spey and was used as fishery protection vessel. There was apparebtly one loss, P12, sunk in collision in the Channel 4 November 1918.

Photos of the P58 with the cliffs in the background: –
Closeup of the model aft at tw museums:
The leander project, aerial view of a P-Boat:

Most of these ships survived the war, being broken up in 1921-23.
However during service many received an additional 14-in TT aft removed from older torpedo boats. It was though they could then cripple an enemy surface warship if attacked during one of the many east coast raids.
P 57 was sold to Egypt 21 May 1920 and renamed El Raqib (fate unknown).
One of the converted PC-Boats (PC 69) was sold to the Royal Indian Navy 5 August 1921, renamed Pathan 30 May 1922. She was sunk by explosion off Bombay 23 June 1940. PC73 made it until 1938 as HMS Dart. PC74 was renamed HMS Chatsgrove during WW2[ and served as Q-ship from late 1939 until July 1945 and was sold for breaking up 19 July 1948.


Sources, Read More

P boats of the First World War – William Bartram and P23

Author: dreadnaughtz

Naval Encyclopedia webmaster. Find more on the "about" page.

4 thoughts on “British P-Boats (1915)

    1. Thanks Peter,
      I hope to dive in detail in other less-well known naval vessels in the future. ASW ships classes during ww1 were already quite numerous.
      The dreadnaughtz aka David B

  1. Good Afternoon
    I am part of team working on a book about Workman Clar, the Belfast shipbuilder, in the Great War. I would be interested in using the photograph of the P-Class Patrol Boat model in the book and am enquiring about permission and acknowledgement requirements.
    I look forward to receiving your reply.
    Nigel Henderson
    Researcher, History Hub Ulster

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