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HYDROGRAPHIC SURVEY WORK UP TO THE 1980's

 

by Geoffrey B Mason, Lieutenant Commander, RN (Rtd) (c) 2007

Survey ship HMS Dampier  (Navy Photos, click for enlargement) return to Contents List
 

Introduction

 

As. the 200th anniversary of the introduction of the office of Hydrographer of the Navy approaches, it seems appropriate to place on record a little of the history of hydrographic surveying by the Royal Navy. The work of those who carried out survey work has been given little public recognition, the detached parties who spent long periods in very isolated places and undertook almost herculean tasks deserves particular acknowledgement. This articles is intended to set out a little of the background to hydrographic surveying by the Navy since 1930.

 

In 1683, the King Charles II appointed Captain Grenville Collins as Hydrographer to the King and placed him in command of the Royal yacht MERLIN, which can be regarded as the first British warship dedicated to marine survey work as opposed to exploration. Collins completed the first comprehensive survey of the British coast whilst in command of the MERLIN.

 

The responsibility for all survey work considered necessary for the mobility and security of HM Ships has long been discharged by the Hydrographer of the Navy. His office was first established in 1795. Before that date the officer responsible for navigation of individual warship, the Master, was required to undertake survey work aimed at up-dating existing charts or providing new information to the Admiralty for future use. a special hydrographic organisation was first established by France in 1720 and a little later by Denmark. Before the end of the 18th century similar arrangements were made by the Spanish, American and other navies. The motivation for provision of navigational information depended upon the extent of colonial development and foreign trading by individual nations. An International Hydrographic Bureau was set up in Monaco in 1921 and conferences are held every five years. The British Hydrographic Service is represented, and sometimes an HM Survey Ship will go to Monaco to give demonstrations of equipment and to act as host ship for the British representatives.

 

Although the first Hydrographer of the Navy, Alexander Dalrymple, was a civilian employed by the East India Company, he was relieved by a naval officer, Captain Thomas Hurd in 1808. Since that date the office has been exclusive to qualified Surveying Officers of the RN. It was Hurd who established the requirement that surveys at sea should be carried out by HM Ships, and that all ships deployed specifically for survey work should be manned by Executive (Seamen) officers. These officers were to progress in rank based on their surveying capabilities as well as their basic seamanship abilities. In this way they would be totally fitted to command ships devoted to survey work. This principle still remains today.

 

The Hydrographer's Department produces a series of documents to assist ship navigation. These include charts, sailing directions, tide tables and other publications dealing with navigational lights. In order to ensure that users are made aware of changes or new information, details are promulgated in the form of Notices to Mariners and distributed to holders of Admiralty charts. With the introduction of steel ships, gyro compasses, radio beacons and, more recently, satellite navigational systems, additional supporting publications are now provided.

 

 

Surveying at Sea

 

Hydrography is concerned with accurate positioning of points on the surface of the Globe and, where appropriate, the depth of water available. Early seafarers are known to have used a type of compass and to have appreciated that some form of distance measurement was essential to navigation. Until it was generally accepted that the earth was not flat any charts produced were very inaccurate and parts of the land and other features were out of proportion. They did, however, describe coastlines and indicate shallow water but in many cases not the depth.

 

Before any chart can be produced it is essential that a datum position is established and expressed in terms of latitude and longitude. Latitude was determined by astronomical observations and became more accurate after the sextant replaced the seaman's quadrant. Once a reliable chronometer was available, the determination of longitude was greatly improved. Charts must show details of coastal features to assist the mariner to jdc his position and provided other information, such as, changes in depth of water, especially near coasts. Data for the preparation of sea charts is dependent upon accurate measurement of distances between fixed points whose positions have already been accurately established. However, whereas maps of land surfaces include details of the height of geographical features, which are under normal circumstances fixed, the depths of the seas and oceans are variable due to tidal conditions.

 

 

Principles

 

The properties of a triangle are used to establish the position of fixed points within the area to be surveyed. The triangulatfon process requires accurate knowledge of the distance between two of these points and subsequent angular measurements from these enables the third point to be precisely determined using theodolites or sextants. The position of the first points is established by using existing datum from earlier surveys, or by astronomical observations. Out of sight of land special provision has to be made to mark the fixed points with moored buoys. Extensive use is. therefore, made of small survey boats which are a distinctive feature of all Survey Ships. Angular measurements are made using sextants, theodolites, quadrants and station pointers. This latter device enables the position of a vessel to be plotted with reference to three other known positions.

 

 

Distant Measurement

 

Metallic tapes are used for measurements on land and taut wire measuring gear, for measurement between datum offshore. The latter device consisted of a reel of wire mounted in the stern of a survey ship, from which the wire was pulled off by the forward movement. These methods have been largely superseded by electronic equipment which is easier to use and more accurate. The first of these, the tellurometer, was developed in South Africa for land survey work and introduced into RN service about 1958. A similar instrument the hydrodist, specifically designed for marine survey work superseded the tellurometer and is now in common use.

 

 

Depth Measurement

 

Depth of shallow water is measured using graduated poles placed in selected sites for tidal records. At these tidal stations the depth of water is recorded every ten minutes around the times of high and low water and every thirty minutes intermediately for period of not less than 29 days. Automatically operated equipment is now available which makes this procedure much less arduous.

 

Offshore depth can be measured by the traditional lead and line or by the Kelvin wire sounding machine for depths up to 2,000 fathoms. The echo sounder was first developed during the 1930's and echo sounding equipment is now the method used. It can continuously record the depth of water below a moving vessel. This type of electronic equipment is fitted in all survey ships and craft.

 

In order to establish the minimum depth of water available in approaches to harbours, special procedures are used to confirm that the water is clear of obstructions. Minesweeping cable streamed astern of the survey ship and maintained at a fixed depth. Any wreck or obstruction above the selected depth will foul the wire and its position can then be marked for future attention. Clearance sweeping is more usually carried out by one ship, however two small craft can be used in shallow waters. The availability of more accurate sonar with improved display units enables wrecks and pinnacles of rock to be examined and positioned with great accuracy. Once an obstruction has been located it is now common practice to use shallow water divers to examine it thoroughly and place explosive charges, as necessary, to ensure no portion remains above the clearance required. Sonar which has evolved from the echo sounder is also used for the detection of obstructions.

 

 

Types of Hydrographic Work

 

Hydrographic work can be broadly divided into two areas — ocean survey and inshore survey. Large vessels able to carry out their work in sea areas far from land are used for ocean survey and small craft for inshore and coastal work. Since 1930. at least. 40 survey ships have been employed during peacetime. These are listed as an Appendix, and this shows that most of them were converted for survey work with only a few designed and built specifically for the purpose.

 

Detached parties with small survey boats are extensively used for inshore survey work. Their principal functions are to:

 

Establish clearly visible datum positions based on existing survey or accurately determined by normal  survey practice.

 

Fix the coastline and conspicuous features visible from the sea.

 

Fix the position of islands, shoals and dangerous obstructions.

 

Establish tidal stations and make recordings of depth of water.

 

Carry out sounding work in shallow areas not accessible by the parent ship.

 

Until radio position finding equipment became available survey work required good visibility for optical measurements and sea conditions had to be suitable for small craft. The advent of electronic equipment for accurate position finding enables survey work to be carried out by day and by night in weather condition: previously impracticable, this has revolutionised the output produced in each surveying season.

 

Radio Position Finding Equipment

 

Radio position finding systems operate on hyperbolic principles and allow distances from shore based transmitter stations to be obtained using special receiving equipment fitted onboard ships. Hyperbolic radio navigational aids were first used by aircraft during World War Two - the Gee system - and were adapted for use in ships. After the end of hostilities the British designed Decca Navigator System was set up to provide this facility for commercial use and Decca Navigator equipment was progressively fitted in RN ships. It had great potential as a tool for survey work and shipboard equipment was fitted in all survey ships during the early 1950's. This system enables a ship's position to be continuously obtained using charts overprinted with a special lattice network representing radio signal measurements for a given covered area. The receiving equipment incorporates a display unit from which readings corresponding with the lattice are obtained to determine position. A similar system was also developed in the USA during World War Two and is known as LORAN. A modified form - Two Range Decca - was developed for marine survey purposes and includes a radio transmitter carried on board the survey ship, which therefore, became totally independent of the commercial Decca system.

 

Detached parties ashore and in survey boats were provided with suitable portable receive sets to enable them to fix their positions accurately using large scale charts of the area. A lattice network corresponding with the shipboard equipment is overprinted on these charts. Ships fitted with this type of equipment are easily identified by the tall mainmast structure supporting the radio transmitting aerial system. A later variant of this special survey system - Hifix - has gradually replaced the Two Range Decca. This includes portable transmitters which are set up ashore in precisely located sites and provide a network of radio position lines over the survey area. A marine radar outfit specially designed for survey; work and with a range accuracy of within 10 yards is used for distance measurements between established datum. Radar transponder beacons, accurately positioned at datum points are also used to assist modern hydrographic survey work.

 

Tidal Measurements

 

Horizontal movement of water on the earth's surface is of great concern to ship navigation, and demands attention during hydrographic work. Tidal streams are influenced by many factors, apart from changes in the position of the sun and moon. Seasonal changes of wind direction and differences in atmospheric pressure are two examples. Observations are made at the average depth of water required by ships in the survey area. Records of mean direction and rate of flow are needed at hourly intervals for up to 50 hours and repeated in different lunar conditions, a uniform diameter spar is frequently employed and floated vertically. It must be long enough to reach the depth required and needs a distinctive marker so that its movement can be assessed from shore or from an accompanying craft.

 

 

Additional Equipment used in Hydrographic Survey

 

Satellite navigation equipment

 

Traditional methods of astro-fixing of position for latitude and longitude measurement have now been replaced by use of radio satellites. A ship's position is instantaneously available which is quite invaluable for survey use, as for example, when lines of soundings are being measured.

 

Magnetometers

 

In order to determine the extent of changes in the strength of the earth's magnetic field, magnetometer design has been much improved to provide equipment robust enough for towing by a survey ship. The 'Proton' variant, developed by London University, was extensively used in the Indian Ocean during an international scientific investigation in the 1960's. Changes in the natural magnetic field owing to the presence of submarines is one practical application of this type of unit.

 

Bathythermographs

 

Trials to establish the effect of different sea temperatures on acoustic underwater transmissions were first carried out in 1922 in the Mediterranean and the Red Sea. changes in salinity and temperature at different depths of water have a significant effect on the performances of sonar and echo sounding equipment. Bathythermograph equipment used to measure sea temperature at various depths was developed, during World War Two, by the famous Woods Hole Institute of Oceanography. Charts and tables issued by The Hydrographer are based on measurements now made as a matter of routine by all HM Ships.

 

Core sampling equipment

 

Study of the make up of the earth's crust has become increasing important. Progressive developments have resulted in the availability of devices suitable for shipboard use. Samples are obtained during ocean passages for use by scientists ashore who are carrying out mineralogical research.

 

Data processing outfits - Computers

 

Modern radar, sonar and navigational aids are able to provide a continuous supply of information. This has to be analysed and presented in a format suitable for use by hydrographers. Automatic data processing equipment is therefore an essential tool and allows speedy availability of the particular information needed.

 

 

Conclusion

 

The availability of modern techniques has made hydrographic survey a very complex activity and greatly reduce the time taken to complete survey work. It has not affected the need for dedicated and determined personnel, prepared to work long hours often far away for the amenities of the modern world. These characteristics are still a fundamental requirement and cannot be replaced by any of the technological advances of the latter years of the 20th century.

 

 


 

 

 

Chronological Summary

 

 

1801

First Admiralty Chart published.

1807

Naval Chart Committee came into being.

1819

Admiralty takes over Royal Observatory, Greenwich.

1819

Permission given to sell Admiralty Charts to the Merchant Marine

1823

First Sailing Directions published by Hydrographer.

1829

First Light List published by Hydrographer.

1832

Promulgation of information to keep charts up-to-date began in the Nautical Magazine.

1833

First Tide Tables published by Hydrographer.

1834

First Notices to Mariners issued by Hydrographer.

1842

Admiralty compass Department set by Rear Admiral Sir Francis Beaufort (1774-1857), who was the Hydrographer for 26 years. He gave his name to the scale used for wind and weather.

1902

International Council for the Exploration of the Sea established in Copenhagen.

1919

World's first International Hydrographic Conference.

1921

International Hydrographic Bureau established in Monaco.

1922

First Admiralty List of Wireless Stations published.

1967

International Hydrographic Bureau is renamed the International Hydrographic Organisation.

1968

Automatic Data Processing equipment (computers) first introduced in HM survey ships.

1971-80

International Decade of Ocean Exploration

1978

RN Hydrographic Apartment received the Queen's Award for Export Achievement.

 

 

 

 

ROYAL NAVY SURVEY SHIPS SINCE 1930

 

 

Ships Designed as Survey Ships

 

Class, Ship’s Name

Displacement Tonnage

Period of Service

Remarks

 

 

 

 

1 ENDEAVOUR

1280

1913-42

War Service as a Survey Ship

2 CHALLENGER

1140

1931-52

War Service as a Survey Ship

3 VIDAL

2000

1954-71

First to have Helicopter facility

 

 

 

 

HECLA Class

 

 

 

4 HECLA

2800

1965-

A133

5 HECATE

 

1965-90

A137 Disposal 1991

6 HYDRA

 

1966-86

Sold to Indonesian Navy in 1986 and renamed DEWA KEMBA

 

 

 

 

 

Improved HECLA Class

 

 

 

 7 HERALD

2900

1974-

A138

 

 

 

 

BULLDOG Class

 

 

 

 8 BULLDOG

1088

1968-

A317

 9 BEAGLE

 

1968-

A319

10 FOX

 

1968-90

A329

11 FAWN

 

1968

A325

 

 

 

 

12 GLEANER

20

1984

A86 Inshore Survey Craft

13 ROEBUCK

1400

1986

A130

 

 

Survey Ships converted from other hulls

 

ABERDARE Class

 

 

Minesweeper

 14 BEAUFORT

800

1920-35

 

 15 FITZROY

 

1920-38

 

 16 FLINDERS

 

1920-38

 

 17 KELLETT

 

1920-88

 

 

 

 

 

 RACEHORSE Class

 

 

Patrol Sloop

 18 IROQUOIS

1320

1923-31

 

 19 ORMONDE

 

1924-36

 

 20 HERALD

 

1924-39

ex MERRY HAMPTON was taken into Japanese service as HEIYO; she was mined in 1944.

 

 

 

 

 BITTERN Class

 

 

Sloop

 21 STORK

1190

1936-39

Then reverted to Escort role

 

 

 

 

 HASTINGS Class

 

 

 

 22 SCARBOROUGH

1025

1938-38

Then reverted to Escort role

 23 FOLKESTONE

 

1938-38

Then reverted to Escort role

 

 

 

 

 HALCYON Class

 

 

Minesweeper

 24 FRANKLIN

815

1938-52

War Service as Survey Ship

 25 SCOTT

 

1939-64

War Service as Survey Ship

 26 JASON

 

1938-39

Reverted to Minesweeper role

 27 GLEANER

 

1938-39

Reverted to Minesweeper role

 28 SEAGULL

 

1946-54

Converted 1945-46

 29 SHARPSHOOTER

 

1946-59

Renamed HMS SHACKLETON in 1955.

 

 

 

 

 LOCH/BAY Class

 

 

 

 30 DAMPIER

2600

1948-68

ex LOCH EIL, ex HERNE BAY.

 31 DALRYMPLE

 

1949-65

ex LOCH GLASS, EX LUCE BAY. sold to Portugal in 1966 and renamed

ALPHONSO DE ALBUQUERQUE.

 32 OWEN

 

1949-65

ex LOCH MUICK (2), ex THURSO BAY.

 33 COOK

 

1950-64

ex LOCH MOCHRUM, ex PEGWELL BAY.

 

 

 

 

E Class

 

 

 

34 ECHO

160

1958-84

A70 Ex Ham Class

35 EGERIA

 

1958-84

A72

36 ENTERPRISE

 

1959-84

A71

37 WOODLARK

 

1955-80

M2780 Ex YAXHAM

38 WATERWITCH

 

1966-81

M2720 Ex POWDERHAM

 

 

 

 

 Ton class

 

 

 

39 MERMAID

425

1964-68

M1184 Ex SULLINGTON

40 MYRMIDON

 

1964-68

M1111 Ex EDDERTON.   Sold to Malaysia in 1969 and renamed PERANTAU.

       

41 WHITE BEAR

 

 1939-45

Ex-Yacht ISOLAIRE

 

 

 

 

 Special

 

 

 

42 ENDURANCE

3706

1968-91

A171. Ex-ANITA DAN Ice Patrol Ship converted 1967/68

 

 

 

The Hydrographer's Navy — photographic profile (Photographs being sought)

 

 

Survey ships are painted in an internationally agreed colour scheme .white hull, buff funnel.

 

® SAS NATAL — this fine photograph illustrates the ex Loch/Bay class frigate HMS LOCH CREE. Launched by Swan Hunter on 19 June 1944 she was handed over to the South African Navy in 1945 and subsequently converted for service as a survey vessel. [South African Navy photograph via author]

 

® HMS COOK - ex Loch/Bay class frigate LOCH MUICK/PEGWELL BAY. Launched by Pickersgill in September 1945 she was converted for service as a survey vessel. While still resembling her frigate ancestry this photograph clearly shows the large davits required to handle her Survey Motor Boats. [Admiralty photograph via author]

 

® HMS BULLDOG — Bulldog class Coastal Survey Ship, built by Brooke Marine of Lowestoft and commissioned on 21 March 1968. Based on a commercial design, she and her three sisters are capable of worldwide operations. Powered by 4 8-cylinder diesel engines she has an endurance of 4,500 nautical miles at 12 knots. Manned by a crew of 4 officers, 9 senior rates and 38 junior rates — the 4 officers and one PO are surveyors. This ship is fitted Hydrosearch sonar which is considered the most advanced in the world. She also carries a 31 foot Survey Motor Boat and an 18 foot Survey Launch. [Builders photograph via ANRS]

 

® HMS HECATE — Hecla class Ocean Survey Ship, built by Yarrows at Scotstoun and commissioned in December 1965. Based on a commercial design, she and her two sisters were built for worldwide hydrographic and oceanographic operations. She has an ice strengthened hull, a fully equipped flight deck and helicopter hanger and two 31 foot Survey Motor Boats. Crew 12 officers and 104 ratings. Main propulsion is diesel-electric with 3 12-cylinder diesel engines; speed 14 knots This photograph clearly shows the Hifix position fixing system aerial atop the hangar. [WSPL]

 

® HMS EGERIA — E class Inshore Survey Craft. EGERIA and her two sisters — ECHO and ENTERPRISE formed the Inshore Survey Squadron. This squadron was first commissioned in 1958 and normally worked out of Chatham Dockyard. The main role of the squadron was to provide a continuous resurvey of the East Coast of Great Britain from Dover to the North of Scotland. EGERIA was launched in September 1958 and the hull design was based on that of the Ham class inshore minesweeper. Crew 2 officers and 16 ratings. [WSPL]

 

 

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