Royal Navy coastal forces in the early Cold War period.

[Comrade Dave]

I’ve been researching the Royal Navy’s coastal forces build up during the Korean War, I have decided to attempt to collect and catalogue existing classes and shore bases while attempting to uncover more details about the “could have beens” during the period. I will explain the reasoning behind the decisions made as best I can but please feel free to add on or adjust if you have any information on the matter

Patrol boats/seaward Defence craft.
The end of World War II saw a massive reduction in Coastal Forces although the Royal Navy continued to use various types of fast patrol boats until the late 1970s. Coastal Forces bases around the British coast closed with cessation of hostilities although HMS Hornet, at Gosport, continued in commission until 1957. Some World War II Vosper, British Power Boats, Fairmile Bs and Camper and Nicholsons craft were retained until the mid1950s. Nine ex short British Powerboat MTBs were modified as the “Proud Class” and a large number of Harbour Defence Motor Launches were redesignated as Seaward Defence MLs and used for a wide range of coastal tasks. These were joined by the Gay Class, twelve interchangeable MTB / MGBs which entered service during 1953 and 1954 at the start of the Korean War. These Gay Class, a 71’ 6” craft with a displacement of 50 tons and of wood construction and with 3 Packard engines, proved to be the last of the traditional high octane petrol craft to enter service. These boats were largely a repeat of wartime designs, which served an interim purpose until the diesel machinery was available for a totally new design to be known as the Dark Class. Entering service at the same time in 1953 were two Bold Class 140 ton, 116 foot craft, Bold Pioneer and Bold Path Finder. These larger craft with two 4.5” guns and four 21” torpedoes, were powered by novel machinery for the time. Although initially fitted with captured Mercedes diesel engines, each was eventually fitted with two Metropolitan Vickers gas turbine engines and with the two Diesels, giving a speed of 40 knots. Nineteen Dark Class were eventually ordered, built with metal frames with wooden hulls, and each powered with two Napier Deltic engines; eventually eighteen were commissioned.

Following the Admiralty decision in 1957 to take nearly all fast patrol boats out of commission, nine of these new Dark class were to be laid-up. But on 20 December 1960 the Admiralty stated that the Coastal Forces were not being completely abandoned and a nucleus were to be kept alive so that the art would not be lost and in order to provide the foundations on which the Coastal Forces could be rapidly expanded if needed. A special boat squadron was nominated with two new Brave class and one Bold class, The Admiralty therefore considered that this preserved the foundations on which the focus could be rapidly expanded if needed.

Classes introduced during the period.
Brave class fast patrol boat.
(2 planned, 2 built)

Dark class fast patrol boat.
(27 planned, 19 built)

Bold class fast patrol boat.
(2 planned, 2 built)

Ford Class seaward Defence craft.
(20 planned, 20 built)

Gay Class fast Patrol boat.
(12 planned, 12 built)

Proud Class fast Patrol boat.
(6 planned, 6 acquired)

Classes existing during the period.
Harbour Defence motor launch.
(30 modified for seaward Defence)

Fairmile B type fast patrol boat.
(48 modified for seaward Defence)

MTB-601 type fast Patrol boat.
(44 on the Navy list, most likely in reserve)

MTB-511 type Fast Patrol Boat.
(8 on the Navy list, most likely in reserve)

Grey goose type steam gunboat.
(Trials boat)

Potential classes/modifications cancelled.
Ship systems.
CFS2 Gun Mount for 3.3in Gun.
(Cancelled as too big)

Rolls Royce RM60 gas turbines.
(Cancelled but source states returned for Type 45 Development)

Patrol craft.
The “ultimate” Patrol craft, Capable Of cruising to the Dutch Coast to fight an action and then returning. All while maintaining 50kts speed.
(the source material is quite vague on this one)

Further Brave Class orders potentially?

Next is mine Warfare Development.

 

[Comrade Dave]

Mine Warfare ships and systems.

At the start of the Cold War the principal minesweeper of the Navy was the Algerine class minesweeper, the Soviet Navy began to prepare for a massive play in the Mine Warfare Role, partly evidenced by the Korean War. 1950 estimates where that the Soviets could lay 4,500-5,00 mines in British waters a month, and as a rule of thumb It would take 25-30 mines laid for a ship to strike one. Losses of 50 merchant ships a month was considered “tolerable” and there Mine numbers had to be kept down the 1,500-2,000.

The new soviet type magnetic mines ruled out a modernisation of the Steel hulled Algerines as the mines could beat Degaussing procedures of the time. As the mines could also be activated in a number of different ways, meaning that each channel had to be swept 12 times before it could be considered cleared of mines.

Classes introduced during the period.
Ton class coastal mine sweeper.
(167 planned, 118 built)

Ham class inshore minesweeper.
(167 planned, 93 built)
(Construction program Shared with Leys)

Ley Class inshore minehunter.
(167 planned, 11 built)

Classes existing during the period.
Abdiel Class Cruiser Minelayer.
(3 in service/converted to support ships)

Miner class minelayer.
(8 in service)

Plover/Linnet Class minelayers.
(3 on Navy list/most likely in reserve)

Algerine Class minesweeper.
(72 on Navy list/some modernised/most in reserve)

Bangor Class minesweeper.
(5 on Navy list/most likely in reserve)

Halcyon Class minesweeper.
(3 on Navy list/most likely in reserve)

Isles class trawler minesweeper.
(25 on Navy list/in reserve)

Motor minesweepers.
(50 on Navy list/in reserve)

Cancelled classes.
The Ocean minesweeper.
(Essentially an updated Algerine at 1,500 tonnes. Cancelled due to lack of relevancy for the type, there’s a good picture of this on shipbucket for those curious)

The Improved Algerine.
(Either a new class similar to the OMS or just modernised Algerines)
(50 planned in case of CMS program delays)

Thorpe Class minehunter.
(Development Of the Ton Class)
(3 ordered before cancellation)

Ship Systems.
Anti-pressure Mine plastic bags.
(Later developed into Dracones to carry oil)

Compound Deltic engine.
(Based on the Nene engine but work stopped when coastal forces abandoned)

Next is shore establishments.

 

[Yellow Palace]

Classes introduced during the period.
Ton class coastal mine sweeper.
(167 planned, 118 built)

Ham class inshore minesweeper.
(167 planned, 93 built)
(Construction program Shared with Leys)

Ley Class inshore minehunter.
(167 planned, 11 built)

Curious numbers, I have 50 ALGERINE, 135 TON class and 167 HAM/LEY class as the planning figures; I think this was from Vanguard to Trident but can't check at the moment.

 

[Comrade Dave]

I could have been clearer on the Ham/Ley Part. the 167 ships in shared between the two not 167 each, Rebuilding the Royal Navy states 167 coastal minesweepers, not necessarily ton class entirely so maybe there were plans for 32 of the “Thorpe” class before cancellation.

 

[Comrade Dave]

Shore establishments.
Coastal forces shore establishments, were either attached to main naval dockyards, akin to Dolphin at gosport, or standalone establishments. Most were closed down by the end of the Second World War.

Overseas establishments were not true Coastal forces bases, more general supply, refit bases with coastal forces attached.

Shore establishments.
Home:
HMS Cochrane. (Rosyth)
(closed 1998)

HMS Diligence. (Southampton)
(closed 1963)

HMS Hornet. (Gosport)
(Closed 1957)

HMS Lochinvar (south queensferry)
(Closed 1975)

HMS Vernon (Portsmouth)
(Closed 1996)

Overseas:
HMS Jufair. (Bahrain)
(Closed 1971)

HMS Sheba. (Aden)
(Closed 1967)

HMS St Angelo. (Malta) (Msaida Creek)
(Closed 1964)

Next is support vessels and depot ships.

 

[Hood]

Compound Deltic engine.
(Based on the Nene engine but work stopped when coastal forces abandoned)

I just want to query this. I thought the Compound Deltic was based on Napier's work on the Nomad?

This is a very useful set of summaries of the coastal forces.

 

[Comrade Dave]

Development of the engine started at Napier’s but was based on the Nene engine, not the Nomad.

 

[Comrade Dave]

Support and Depot ships.
Classes existing during the period.
HMS Mull Of galloway. (Headquarters ship)
(Scrapped 1965)

HMS Mull Of Kintyre. (Maintenance ship)
(Scrapped 1969)

HMS rame Head. (Depot ship)
(Scrapped 1967)


Classes introduced during the period.
Hms Woodbridge Haven. (Maintenance ship)
(Former Frigate, Scrapped 1965)

HMS derby Haven. (Maintenance ship)
(Former Frigate, Sold 1949)


Links for the information I have found are below plus other non-internet sources.

Ton class association.

TON CLASS ASSOCIATION

Navypedia.

NAVYPEDIA - fighting ships of the world

Navypedia - historical reference site dedicated to all the world fighting ships and navies of XIX - XXI centuries including both World wars. Site contains information about fates of ships, their technical data, their armaments. New volume 'World Naval Balance' is dedicated to modern navies...

www.navypedia.org

Naval history.

https://naval-history.net/xGW-RNOrganisation1947-2013.com

RFA nostalgia.

RFANostalgia - Recent

Royal Fleet Auxiliary Service, Serving the RFA Community,Home page of the RFAA Plymouth& District Branch Website

www.rfanostalgia.org

Rebuilding the Royal Navy by D.K. Brown Andy george Moore. (Book)

Logistics in the Falklands War. (Somehow)
By Kenneth L. Privratsky. (Book)

 

[Grey Havoc]

A few old posts that may be of interest from over in the 'Naval Guns' thread:

Coastal Forces System Mark 2

The gun armament of coastal force craft had for many years been a combination of automatic weapons up to 40 mm calibre and some larger guns such as the six pounder (57mm) and 4.5” (113 mm). The bigger weapons had greater hitting power but doubtful accuracy when used from the poor gun platform provided by a fast moving boat in a seaway. After the war attention was directed to the design of a gun mounting and control system suitable for coastal forces from which the Coastal Forces System Mark 2 (CFS2) was evolved. CFS2 was a fully stabilised, power operated mounting comprising a 3.3” (84 mm) Mk 1N gun on a Mk 1 mounting, with a combined tachometric and eye shooting sight. It was designed for surface vessel engagements and had a training arc of ±135° with a maximum elevation of 20° and maximum depression of 15°. The mounting was normally controlled by the aimer using visual aiming and joystick control. Either navigational radar range or estimated range could be used in the computing mechanism and target bearing indication could be received from either a sight or a navigation radar.

The mounting was a development from the STAAG [Stabilized Tachymetric Anti Aircraft Gun] principles and the gun carried in the standard Centurion tank (20 pounder). It was of 3.3” (84mm) calibre and had a muzzle velocity of 2,600 fps (793 mps), together with a rate of fire of 10 to 14 rounds per minute. The projectile weighed 17 lb 3 oz (7.79 kg) with a total ammunition weight of 34 lb 4 oz (15.54 kg), this being the maximum weight a man could be expected to handle when being subjected to vertical accelerations of the order of 2-3 G, likely to be experienced at the forward gun position in fast patrol boats. The maximum range was 5,000 yards (4,572 m), with an effective range of just 3,000 yards (2,743 m).

Trials of the prototype mounting in HMS Bold Pioneer demonstrated that very high accuracy and rate of fire could be maintained even at high speed in a seaway. This considerable achievement brought its penalty in weight, power, and complication. The weight of the mounting was approximately 6 tons 3 cwt (5,596 kg), excluding ammunition and the three man crew and the power requirements were 220 V DC at 8.5 kW.

Development of the CFS2 was abandoned as part of the RN’s decision not to maintain coastal forces.

From Les Brown’s http://www.smallwarshipgroup.org.uk/.

The CFS2 was very different to the Oto Gun. The CFS2 was a stabilised gun mount with the same 20 pounder gun as fitted to the Centurion tank (later rebored to become the world famous 105mm L7 tank gun). It was manually loaded and aimed unlike the Oto Gun which fired automatically from an under deck carousel and needed a fire control system to find targets.

The CFS2 was to go to sea on the Brave class MTB/MGBs and the deck plan drawings above show it fitted. Those Brave class built all had 40mm Bofors guns except the three for Libya which had a heavier anti boat armament. This was SS.12 guided missile launchers which replaced the CFS2 capability. The missiles replaced the torpedos enabling these boats to retain the fore and aft 40mm guns. Each side of the bridge were racks for four SS.12s each and a stabilised sight forward of the open bridge connected to a gunner’s seat underneath in the pilot house. The SS.12 put a 63 lbs warhead onto a target out to 6,600 yards with high accuracy with a well-trained controller. This is far better performance than the CFS2 in the anti Komar/Osa role.

Each side of the bridge were racks for four SS.12s each

The racks could have taken both SS.12 and SS.11 missiles, as may be seen in the photo attached to your post. If I am not mistaken the French tried a similar system, albeit with a trainable launcher, aboard their (experimental) Combattante-class boats. And there were some, also experimental vehicle-mounted installations with the SS.12 as well as the SS.11.
It seems that both types of missiles used the same guidance system.

Piotr

 

[Grey Havoc]

Great thread,

The very last UK flying boats get little attention here. The P.162 is especially interesting, Buttler mentions it in BSP Jet Bombers. Ken, you mention that the type was to have turboprops but eh graphic states 'compounded diesel engines', I take this to be a reference to the Napier Nomad which was theoretically an ideal engine for an MPA and was in vogue for the Shackleton for quite some time.

Interesting that the original tender was for 80 aircraft; How does this fit in with Shackleton fleet? Of that aircraft 77 Mk1s and 69 Mk2s were acquired. Would the P.162 have been supplemental to this fleet or were additional Shackletons acquired after the death of the Saro bird?

There seems to have been considerable interest in land based naval defence around the UK, the Corsair (Type 191) sonar system was proposed as a defensive net to help direct aircraft to targets. There was also the never deployed Type 188 harbour defence sonar. The Coastal forces existed until 1957 and considerable effort went into developing gas turbine powered boats for them. In addition there were early plans to use the Valiant as a launch platform for the Green Cheese AShM. That there was also an effort to provide a replacement for the Sunderland is another interesting layer to this.