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The orders "Up periscope" and "Down periscope" are, for most of us, completely tied in with our notion of submarines. These are phrases that we've heard countless times in submarine movies, in which there's usually a dramatic scene of a submarine captain hanging onto the handles of a periscope, looking out at the enemy above the water. Standing watch at the periscope like this is called "dancing with the grey lady".

A periscope's basic purpose is to allow submarine crews to see objects above the water while the ship remains submerged. A simple periscope can be constructed out of a vertical tube with mirrors placed at a 45-degree angle at the top and bottom of the tube. These devices basically collect light from an image and direct that light from one mirror at the top of the periscope to the mirror at the bottom of the periscope. Of course, modern submarine periscopes are far more sophisticated than that.

Sir Howard Grubb (1844-1931) designer of the first practical periscope
Sir Howard Grubb (1844-1931) designer of the first practical periscope

Sir Howard Grubb

Although the principles of the periscope were well known beforehand, Sir Howard Grubb (1844-1931) was the first to design a practical periscope for use in a royal Navy submarine.

For all its innovations the early USS Holland submarines had at least one major flaw; lack of vision when submerged. The submarine had to broach the surface so the crew could look out through windows in the conning tower. Broaching deprived the submarine of one of its greatest advantage, stealth. Lack of vision when submerged was eventually corrected when Simon Lake used prisms and lenses to develop the omniscope, forerunner of the periscope.

Sir Howard Grubb, designer of astronomical instruments, developed the modern periscope that was first used in the Royal Navy Holland Class submarines.

Thomas Grubb (1800-1878) founded a telescope-making firm in Dublin. Sir Howard Grubb's father was noted for inventing and constructing machinery for printing. In the early 1830s, he made an observatory for his own use equipped with a 9-inch telescope. Thomas Grubb's youngest son Howard (1844-1931) joined the firm in 1865, under his hand the company gained a reputation for the first-class Grubb telescopes. During the First World War, demand was on Grubb's factory to make gunsights and periscopes for the war effort and it was during those years that Grubb perfected the periscope's design.

Early Periscopes

Traditionally, a submarine has two periscopes: an attack periscope and a search periscope. The search periscope is used to look for targets and also for guidance as the sub navigates through the water. The attack periscope is smaller than the search periscope and therefore harder to detect as it breaks the surface, it is used by the sub during an attack, hence its name.

The first boats to be fitted with two periscopes were the C Class, although then it was for entirely different reasons as Domville-Fife in his book published in 1910 states:

The C boats were fitted with two periscopes instead of one. The reason being that the range of vision of this instrument is barely 60° and thus, as we suppose to have been the case in the accident to A1. It is impossible for the officer in command to keep constantly in view a certain portion of the surface when the vessel is submerged. The two periscopes obviate this difficulty.

Vision when submerged is most difficult. The range of vision is small and in a rough sea it is impossible to see any distance ahead. Much has been said about the vibration of the periscope caused by the propelling machinery and the water friction on the periscope tube.

Prior to 1911, Sir Howard Grubb held the monopoly for periscopes for RN submarines. The periscopes were bad both as regards strength and vibration. Furthermore Vickers (who built for Grubb) apparently did not use non-magnetic steel tubes since they could not be obtained in this country. In 1911 representatives of DNC and Commodore (S) visited the works of Officino Galileo in Florence, Messrs Goertz in Berlin and Messrs Lacour-Berthiot in Paris. In all cases the periscopes shown were optically and mechanically better than the British types.

As a result of these visits orders were placed in 1912 for six German (Goertz) periscopes, and a further six were ordered later, and for one French (Lacour-Berthiot) periscope for trial.

The Lacour-Berthiot periscope was fitted in C34 for trial and proved very satisfactory especially in the small diameter of the top of the periscope of only 2⅝in. This was a good feature in all French periscopes.

What exactly happened to the Goertz periscopes is not known but neither the French nor the German periscopes appear to have been adopted. However some good came from this exercise and the Grubb periscopes were improved. In E1 to E6 the periscope tubes were made of brass and later boats had non-magnetic steel tubes.

Messrs Kelvin Bottomley and Baird manufactured Italian periscopes for S1 and presumably arranged to work the Galileo rights in this country. They later on got similar rights to work the Goertz patents.

The length and size of periscopes varied with the size of the vessel and the policy at the time.

For Example:

  • The K Class had one Grubb and one Kelvin type 30ft periscope, the longest yet fitted.
  • In the M Class one of the main periscopes was used for range finding. An extra periscope for gun control was fitted to the director tower just abaft the 12-inch gun.
  • Although much smaller boats the R Class had 30ft periscopes with a travel of about 13ft. When housed the tops of the periscopes were below the level of the bridge side plating,
  • X1 had three periscopes one 7½in 30ft long, one 7½in 36ft long and one 8½in 42ft long.
  • The Oberon Class and Odin Class, Parthian Class and Rainbow Class had two 40ft periscopes, one 9½in and one 7½in . In Oxley and Otway both 40ft periscopes were 7½in.

Development of the Modern Periscope

Beginning WWI Inter War WWII Cold War Electronic age Remote Control Systems Optronic Mast Era
Grubb CH1 CK1 CH38 CH63 CL8 CH74 CK24 CH82 CH80 CK34/CH84 CK35/CH85 CK51/CH91 CK43/CH93 CM10 LPV ULPV
First Periscopes fitted to Holland Class boats First Non-Rangefider Periscope First True Binocular Periscope Periscopes for US and other export navy customers Free-French Navy Periscopes X-Craft Periscope First II Periscope First EW Periscope First IR Periscope First Laser Periscope First Electronic Perscopes First Remote Control Periscopes First Optronic Periscopes First Full Remote Control Periscopes Optronic Mast Sea Trails Astute Production 2nd Generation Surveillance Optronic mast Stealth Ootimised Next-gen System
1901 1918 1925 1930 1942 1943 1965 1974 1978 1979 1983 1986 1991 1993 1998 2000 2018  

In 1888, Professor Archibald Barr and Dr William Stroud, in response to a tender issued by the War Office, submitted an application for an optical range-finder patent to the Patents Office. This patent would both cement the collaboration between Barr and Stroud and, from 1917, form the core of the next 100 years of periscope development.

Between the years 1888 and 1915, Professor Barr and Dr Stroud expanded their business to become the number one range-finder company in the UK; developing a reputation for technical excellence in range-finding technology.

In December 1915, Commander S S Hall of the Royal Navy had approached Glasgow based Barr & Stroud Ltd, now part of the modern-day Thales UK, to investigate the feasibility of integrating an optical rangefinder into a periscope. As the UK's leading supplier of military rangefinders, the Company rose to the challenge and within 7 months had built a fully-functioning mock-up. That led to their first contract for a quantity of 6 FY1 periscopes being placed on 15th September 1916. According to company records, one of those first periscopes was shipped via Liverpool to the US Navy in New York in May 1918.

The 25th of August 1917 was the day on which Barr and Stroud officially delivered its first submarine periscope to the Royal Navy. The very first periscope, FY1 Serial Number 1, was fitted to HM Submarine M3 which was then based at Rosyth Royal Dockyard.

M3 while she still had her gun
M3 while she still had her gun

The inter-war period from 1919–1939 marked a time of technical innovation and customer growth for the periscope business including the Royal Navy's first true binocular periscope; the CK1, which made watch keeping for extended periods much easier.

Lieutenant Basil Charles Godfrey Place VC
Lieutenant Basil Charles Godfrey Place VC
Lieutenant Donald Cameron, VC. Royal Naval Reserve
Lieutenant Donald Cameron, VC. Royal Naval Reserve

During the defence of Britain in WWII, one of the most incredible missions of this period, Operation Source, took place in September 1943 when a small group of X Craft midget submarines, each fitted with a single Barr & Stroud CL8 periscope, attacked the 52,000 ton German battleship Tripitz in Kåfjord in northern Norway. The mission resulted in the Victoria Cross being awarded to Lt Donald Cameron, the commanding officer of X6 and Lt Basil Place, the commanding officer of X7, both of whom subsequently visited Glasgow to thank the workforce for their efforts.

Tirpitz in Norway
Tirpitz in Norway

After the Second World War, as the world moved into the Cold War era, submarine operations highlighted the need for periscopes optimised for surveillance and intelligence gathering roles. The CK24 Search and CH74 Attack Periscopes fitted to the Royal Navy's diesel electric Oberon Class Submarines provided the benchmark.

From the late 1960's through to the early 1980's, the Royal Navy acquired unprecedented levels of operational capability with the world's first thermal imaging periscope (CH82) and the world's first laser rangefinder periscope (CH80). The change to an electronic system set the standard for the future and provided the basis for subsequent leading edge sensor upgrades, ensuring the Royal Navy maintained its world class operational capability.

The advent of the electronic age, during the late 1970's saw the introduction of Thermal Imaging sensors and Laser Rangefinders to Royal Navy periscopes in 1978 and 1979 respectively. The use of electronics in periscope design architecture facilitated a transition to limited remote control, followed by full remote control systems.

In the mid to late 1980's, the Royal Navy's Upholder Class (now the Royal Canadian Navy Victoria Class) CK35 and CH85 periscopes introduced remote control of key functions such as elevation and depression of line of sight, image magnification, range measurement and periscope rotation. Imagery from thermal imaging and TV sensors could now be controlled and displayed on screens in the control room and made available to the entire command team, not just the commander. Fully implemented Vanguard Class CK51/CH91 periscopes during the early to mid-1990's, remote control technology had finally reached a level of maturity to enable the next generation of above water sensor systems – the optronic mast.

Optronic masts

Optronic masts are electronic imaging systems and do not penetrate a submarine's hull, but are contained in the conning tower or 'fin'. The smaller size of the periscope well allows for more freedom in determining the location of the ship's control room. With conventional periscopes, the control room had to be placed in the cramped upper deck. A photonics periscope allows the control room to be located on the roomier second deck. Images from the photonics masts are sent via fibre-optics to two workstations and a commander's control console.

In 1998, the first CM10 optronic mast was sea-trialled on HMS Trenchant and brought about a significant change in the Royal Navy's above water visual system capabilities. Today, each Astute Class submarine has two Thales CM10 optronic masts, each fitted with a fully integrated ESM/EW sensor package and with TV, thermal imaging or images being remotely controlled and displayed on consoles within the control room.

Ambush with a CM010 mast raised. Each mast system comprises a single-window sensor head unit, which houses the electro-optical sensors.
Ambush with a CM010 mast raised. Each mast system comprises a single-window sensor head unit, which houses the electro-optical sensors.

Today state-of-the-art optronic masts can complete a full 360° sweep of the horizon, looking for potential threats, in only a few seconds, providing high definition images of the battle space to commanders before they are detected by an adversary.

Thales are currently bidding competitively to have their optronic masts procured for the BAE Systems Maritime build of four new Dreadnought nuclear deterrent submarines which will come into service in the 2030s. The company will conduct sea trials of their latest mast in 2018.


1 comment

The image supposed to be of twin CM010 optronic masts appears to be the attack and search of the former Upholder class of submarine. CH085 & CK035 respectively.

Interesting stuff, though. Thanks.
   George McLean Sat, 10 Apr 2021

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The History Of The British Submarine PeriscopeSubmarine Camouflage Schemes