Code letters or ships call sign were a method of identifying ships before the introduction of modern navigation aids and today also. Later, with the introduction of radio, code letters were used as radio call signs. In 1857, the United Kingdom sponsored the Commercial Code of Signals for the Use of All Nations at Sea, the Commercial Code of Signals, c. 1900, was modified to become the International Code of Signals, by the 1860s, individual ships were being allocated code letters in the United States and Europe. From 1874, code letters were recorded in Lloyds Register as part of individual vessels entry in the register. Generally, code letters allocated to a ship remained with that ship, Code Letters were sometimes reallocated once a ship had been struck from the register, but no two ships bore the same code letters at the same time. With the introduction of radio for communications, code letters were used as radio call signs, Code letters used the twenty-six flags that represent the letters of the alphabet, plus the ten flags that represent the digits 0 -9 have been used.
The substitute flags have not been used for call signs, if the ships call sign is 3EJH2 the seamen never say Three E J H Two. They say Three Echo Juliet Hotel Two to avoid misunderstanding as every country seamen have own pronunciation of letters, if call sign has 4 characters, the first character or figure of ships call signs means country code for the ships registered under this country flag. If call sign has 5 characters, the first two characters or figure plus character of ships call signs means country code for the registered under this country flag. The variations 4 or 5 characters due to 36 characters are not enough for all countries, for or the Soviet Union was used character U as the first character in call signs, cargo ship Metallurg Anosov had call sign USMW. In case that the changes the flag she has to change call sign also. For example, the ship Heinrich Arp, Code Letters RDWL were changed to Code Letters DHKV, if the ship is scrapped or sunk, her call sign can be given to another ship and, usually after a long time.
The last three characters of ships call sign usually mean nothing, but can be one of them used as a code of the government Shipping Companies if the country has more than one Shipping companies and this book must be fresh due to renewal. In this book mentioned, Call sign formed from the call sign series in accordance with Article 19. The sign = in this column indicates that the name of the ship is used to identify the station in radiotelephony, some canals or narrow places have special requirements for the ships to hoist the ships call sign by flags during the transit of this places. It must be mentioned in the maritime books. The Suez Canal requirements includes it in XX century, but today it is not compulsory
Greenock is a town and administrative centre in the Inverclyde council area in Scotland and a former burgh within the historic county of Renfrewshire, located in the west central Lowlands of Scotland. It forms part of an urban area with Gourock to the west. The 2011 census showed that Greenock had a population of 44,248 and it lies on the south bank of the Clyde at the Tail of the Bank where the River Clyde expands into the Firth of Clyde. The name of the town has had various spellings over time and it was printed in early Acts of Parliament as Grinok, Grinock, Greinnock, and as Greinok. Old Presbyterial records used Grenok, a common spelling until it was changed to Greenock around 1700 and it has been suggested that Grian cnoc or sunny hill could refer to the hill on which the castle and mansion house stood, but this has not found much support. The towns modern indoor shopping centre is called The Oak Mall, the name is recalled in a local song. Significantly, no green oak appears on the coat of arms which features the three chalices of the Shaw Stewarts, a sailing ship in full sail and two herring above the motto God Speed Greenock.
Hugh de Grenock was created a Scottish Baron in 1296, around 1540 the adjoining barony of Finnart was passed to the Schaw family, extending their holdings westward to the boundary of Gourock, and in 1542 Sir John Schaw founded Wester Greenock castle. The coast of Greenock formed a bay with three smaller indentations, the Bay of Quick was known as a safe anchorage as far back as 1164. To its east, a sandy bay ran eastwards from the Old Kirk, the fishing village of Greenock developed along this bay, and around 1635 Sir John Schaw had a jetty built into the bay which became known as Sir Johns Bay. In that year he obtained a Charter raising Greenock to a Burgh of Barony with rights to a weekly market, further east, Saint Laurence Bay curved round past the Crawfurd Barony of Easter Greenock to Garvel Point. When a pier was built making the bay an important harbour, in 1642 it was made into the Burgh of Barony of Crawfurdsdyke, and part of the ill-fated Darien Scheme set out from this pier in 1697.
This town was renamed Cartsdyke, the fishing trade grew prosperous, with barrels of salted herring exported widely, and shipping trade developed. As seagoing ships could not go further up the River Clyde, a separate Barony of Cartsburn was created, the first baron being Thomas Craufurd. The work was completed in 1710, with quays extended out into Sir Johns Bay to enclose the harbour, in 1711 the shipbuilding industry was founded when Scotts leased ground between the harbour and the West Burn to build fishing boats. A whaling business operated for about 40 years, in 1714 Greenock became a custom house port as a branch of Port Glasgow, and for a period this operated from rooms leased in Greenock. Receipts rose rapidly from the 1770s, and in 1778 the custom house moved to new premises at the West Quay of the harbour. By 1791 a new pier was constructed at the East Quay, in 1812 Europes first steamboat service was introduced by PS Comet with frequent sailings between Glasgow and Helensburgh, and as trade built up the pier became known as Steamboat Quay
Marine steam engine
A marine steam engine is a steam engine that is used to power a ship or boat. Reciprocating steam engines were replaced in marine applications during the 20th century by steam turbines. The first commercially successful engine was developed by Thomas Newcomen in 1712. The steam engine improvements brought forth by James Watt in the half of the 18th century greatly improved steam engine efficiency. In 1807, the American Robert Fulton built the worlds first commercially successful steamboat, simply known as the North River Steamboat, following Fultons success, steamboat technology developed rapidly on both sides of the Atlantic. The first successful transatlantic crossing by a steamship occurred in 1819 when Savannah sailed from Savannah, Georgia to Liverpool, the first steamship to make regular transatlantic crossings was the sidewheel steamer Great Western in 1838. As the 19th century progressed, marine engines and steamship technology developed alongside each other. A wide variety of reciprocating steam engines were developed over the course of the 19th century.
The two main methods of classifying such engines are by connection mechanism and cylinder technology, most early marine engines had the same cylinder technology but a number of different methods of supplying power to the crankshaft were in use. Thus, early engines are classified mostly according to their connection mechanism. Some common connection mechanisms were side-lever, walking beam, steam engines can be classified according to their cylinder technology. One can therefore sometimes find examples of engines which were classified under both methods, such as the walking beam. Over time, as most engines became direct-acting but cylinder technologies were growing more complex, Some of the more commonly encountered types of marine steam engine are listed in the following sections. Note that not all of these terms may have been used exclusively in relation to marine applications, the side-lever engine was the first type of steam engine to be widely adopted for marine use in Europe. The side-lever was an adaptation of the earliest form of steam engine and these levers extended, on the cylinder side, to each side of the bottom of the vertical engine cylinder. A piston rod, connected vertically to the piston, extended out of the top of the cylinder and this rod attached to a horizontal crosshead which, at each end, was connected to vertical rods.
These rods connected down to the levers on each side of the cylinder and this formed the connection of the levers to the piston on the cylinder side of the engine. The other side of the levers were connected to each other with a horizontal crosstail and this crosstail in turn connected to and operated a single connecting rod, which turned the crankshaft
A hospital ship is a ship designated for primary function as a floating medical treatment facility or hospital. Most are operated by the forces of various countries, as they are intended to be used in or near war zones. Although attacking a ship is a war crime, belligerent navies have the right to board such ships for inspections. In the nineteenth century redundant warships were used as moored hospitals for seamen, Hospital ships possibly existed in ancient times. The Athenian Navy had a ship named Therapia, and the Roman Navy had a ship named Aesculapius, their names indicating that they may have been hospital ships. The earliest British hospital ship may have been the vessel Goodwill, however this experiment in medical care was short-lived, with Goodwill assigned to other tasks within a year and her complement of convalescents simply left behind at the nearest port. It was not until the mid-seventeenth century that any Royal Navy vessels were designated as hospital ships. In addition to their crew, these seventeenth century hospital ships were staffed by a surgeon.
The standard issue of supplies were bandages, needles. Patients were offered a beds or rug to rest upon, the quality of food was very poor. Hospital ships were used for the treatment of wounded soldiers fighting on land. An early example of this was during an English operation to evacuate English Tangier in 1683, an account of this evacuation was written by Samuel Pepys, an eyewitness. One of the concerns was the evacuation of sick soldiers. The hospital ships Unity and Welcome sailed for England on 18 October 1683 with 114 invalid soldiers and 104 women and children, arriving at The Downs on 14 December 1683. A1705 amendment provided for a further five male nurses, on 8 December 1798, unfit for service as a warship, HMS Victory was ordered to be converted to a hospital ship to hold wounded French and Spanish prisoners of war. According to Edward Hasted in 1798, two hospital ships, were moored in Halstow Creek in Kent. The creek is an inlet from the River Medway and the River Thames, the crew of these vessels watched over ships coming to England, which were forced to stay in the creek under quarantine to protect the country from infectious diseases including the plague.
From 1821 to 1870 the Seamens Hospital Society provided HMS Grampus, HMS Dreadnought, in 1866 HMS Hamadryad was moored in Cardiff as a seamens hospital, replaced in 1905 by the Royal Hamadryad Seamens Hospital
A sister ship is a ship of the same class as or of virtually identical design to another ship. Such vessels share an identical hull and superstructure layout, similar displacement. Often, sisters become more differentiated during their service as their equipment are separately altered, for instance, the U. S. warships USS Iowa, USS New Jersey, USS Missouri, and USS Wisconsin are all sister ships, each being an Iowa-class battleship. The most famous ships were the White Star Lines RMS Olympic, RMS Titanic. As with some other liners, the sisters worked as running mates, other sister ships include the Royal Caribbean Internationals Explorer of the Seas and Adventure of the Seas. Half-sister refers to a ship of the class but with some significant differences. Another example is the American Essex-class aircraft carriers of the Second World War that came in long-hull and short-hull versions, for example, the popular TESS-57 standard design built by Tsunishi Shipbuilding are built in Japan and the Philippines.
All the ships of this design are classed as sister ships, the International Maritime Organization defined sister ship in IMO resolution MSC/Circ.1158 in 2006. Criteria included these, A sister ship is a built by the same yard from the same plans. The acceptable deviation of lightship displacement should be between 1 and 2% of the displacement of the lead ship, depending on the length of the ship
Essex /ˈɛsᵻks/ is a county in England immediately north-east of London. It borders the counties of Suffolk and Cambridgeshire to the north, Hertfordshire to the west, Kent across the estuary of the River Thames to the south, the county town is Chelmsford, which is the only city in the county. Essex occupies the part of the old Kingdom of Essex, before this. As well as areas, the county includes London Stansted Airport, the new towns of Basildon and Harlow, Lakeside Shopping Centre, the port of Tilbury. Originally recorded in AD527, Essex occupied territory to the north of the River Thames, incorporating all of what became Middlesex and its territory was restricted to lands east of the River Lea. In changes before the Norman conquest the East Saxons were subsumed into the Kingdom of England and, following the Norman conquest, Essex became a county. During the medieval period, much of the area was designated a Royal forest, including the county in a period to 1204. Gradually, the subject to forest law diminished, but at various times included the forests of Becontree, Epping, Ongar.
County-wide administration Essex County Council was formed in 1889, however County Boroughs of West Ham, Southend-on-Sea and East Ham formed part of the county but were unitary authorities. 12 boroughs and districts provide more localised services such as rubbish and recycling collections and planning, parish-level administration – changes A few Essex parishes have been transferred to other counties. Before 1889, small areas were transferred to Hertfordshire near Bishops Stortford, Essex became part of the East of England Government Office Region in 1994 and was statistically counted as part of that region from 1999, having previously been part of the South East England region. Two unitary authorities In 1998 the boroughs of Southend-on-Sea and Thurrock were granted autonomy from the county of Essex after successful requests to become unitary authorities. Essex Police covers the county and the two unitary authorities. The county council chamber and main headquarters is at the County Hall in Chelmsford, before 1938 the council regularly met in London near Moorgate, which with significant parts closer to that point and the dominance of railways had been more convenient than any place in the county.
It currently has 75 elected councillors, before 1965, the number of councillors reached over 100. The highest point of the county of Essex is Chrishall Common near the village of Langley, close to the Hertfordshire border, the pattern of settlement in the county is diverse. Epping Forest acts as a barrier to the further spread of London. Part of the southeast of the county, already containing the population centres of Basildon and Thurrock, is within the Thames Gateway
Atmospheric diving suit
Divers do not even need to be skilled swimmers. Atmospheric diving suits in current use include the Newtsuit and the WASP, the Newtsuit is constructed from cast aluminum, the upper hull is made from cast aluminum, while the bottom dome is machined aluminum. The WASP is of glass-reinforced plastic body tube construction, in 1715, British inventor John Lethbridge constructed a diving suit. Essentially a wooden barrel about 6 feet in length with two holes for the divers arms sealed with leather cuffs, and a 4-inch viewport of thick glass. The first armored suit with real joints, designed as leather pieces with rings in the shape of a spring, was designed by Englishman W. H. Taylor in 1838, the divers hands and feet were covered with leather. Taylor devised a ballast tank attached to the suit that could be filled with water to attain negative buoyancy, while it was patented, the suit was never actually produced. It is considered that its weight and bulk would have rendered it nearly immobile underwater, lodner D.
Phillips designed the first wholly enclosed ADS in 1856. His design comprised an upper torso with domed ends and included ball and socket joints in the articulated arms. The arms had joints at shoulder and elbow, and the legs at knee, the suit included a ballast tank, a viewing port, entrance through a manhole cover on top, a hand-cranked propeller, and rudimentary manipulators at the ends of the arms. Air was to be supplied from the surface via hose, there is no indication, Phillips suit was ever constructed. The suit had 22 of these joints, four in each leg, six per arm, the helmet possessed 25 individual 2-inch glass viewing ports spaced at the average distance of the human eyes. Weighing 830 pounds, the Carmagnole ADS never worked properly and its joints never were entirely waterproof and it is now on display at the French National Navy Museum in Paris. Another design was patented in 1894 by inventors John Buchanan and Alexander Gordon from Melbourne, the construction was based on a frame of spiral wires covered with waterproof material.
The design was improved by Alexander Gordon by attaching the suit to the helmet and other parts and this resulted in a flexible suit which could withstand high pressure. The suit was manufactured by British firm Siebe Gorman and trialed in Scotland in 1898. American designer MacDuffy constructed the first suit to use ball bearings to provide joint movement in 1914, it was tested in New York to a depth of 214 feet, but was not very successful. A year later, Harry L. Bowdoin of Bayonne, New Jersey, the joints use a small duct to the interior of the joint to allow equalization of pressure. The suit was designed to have four joints in each arm and leg, four viewing ports and a chest-mounted lamp were intended to assist underwater vision
A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the blade, and a fluid is accelerated behind the blade. Their disadvantages are higher mechanical complexity and higher cost, the principle employed in using a screw propeller is used in sculling. It is part of the skill of propelling a Venetian gondola but was used in a less refined way in parts of Europe. For example, propelling a canoe with a paddle using a pitch stroke or side slipping a canoe with a scull involves a similar technique. In China, called lu, was used by the 3rd century AD. In sculling, a blade is moved through an arc. The innovation introduced with the propeller was the extension of that arc through more than 360° by attaching the blade to a rotating shaft. Propellers can have a blade, but in practice there are nearly always more than one so as to balance the forces involved. The origin of the screw propeller starts with Archimedes, who used a screw to lift water for irrigation and bailing boats and it was probably an application of spiral movement in space to a hollow segmented water-wheel used for irrigation by Egyptians for centuries.
Leonardo da Vinci adopted the principle to drive his theoretical helicopter, in 1784, J. P. Paucton proposed a gyrocopter-like aircraft using similar screws for both lift and propulsion. At about the time, James Watt proposed using screws to propel boats. This was not his own invention, though and Hays had patented it a century earlier, by 1827, Czech-Austrian inventor Josef Ressel had invented a screw propeller which had multiple blades fastened around a conical base. He had tested his propeller in February 1826 on a ship that was manually driven. He was successful in using his bronze screw propeller on an adapted steamboat and his ship Civetta with 48 gross register tons, reached a speed of about six knots. This was the first ship successfully driven by an Archimedes screw-type propeller, after a new steam engine had an accident his experiments were banned by the Austro-Hungarian police as dangerous. Josef Ressel was at the time a forestry inspector for the Austrian Empire, but before this he received an Austro-Hungarian patent for his propeller.
This new method of propulsion was an improvement over the paddlewheel as it was not so affected by either ship motions or changes in draft as the burned coal
SS Persia (1900)
SS Persia was a P&O passenger liner, built in 1900 by Caird & Company, Greenock, Scotland. It was torpedoed and sunk without warning on 30 December 1915, Persia was sunk off Crete, while the passengers were having lunch, on 30 December 1915, by German World War I U-Boat ace Max Valentiner. Persia sank in five to ten minutes, killing 343 of the 519 aboard, one reason for the large number of casualties, was that only four of the lifeboats were successfully launched. In this case the Persia was a British ship presenting itself openly to another belligerent, the U-Boat fired a torpedo and made no provision for any survivors. This action took place under Germany’s policy of unrestricted warfare, but broke the Imperial German Navy’s own restriction on attacking passenger liners. At the time of sinking, Persia was carrying a quantity of gold. Among the passengers to survive were Walter E. Smith, a British Member of Parliament, Colonel Charles Clive Bigham, son of Lord Mersey and his secretary Eleanor Thornton, who was the model for the Rolls-Royce Spirit of Ecstasy mascot by Charles Sykes, died.
The survivors on the four lifeboats were picked up during the night after the sinking by the minesweeper HMS Mallow. Only 15 of the women on board survived, among them British actress Ann Codrington, Ann lost her mother, Mrs. Helen Codrington. Sixty-seven crewmen from the Portuguese colony of Goa perished, the sinking was front page news on many British newspapers, including the Daily Mirror and the Daily Sketch. The wreck of Persia was located off Crete in 2003 at a depth of 10,000 feet, the salvage attempt met with limited success, retrieving artifacts and portions of the ship, and some jewels from the bullion room. Some of the gems have since been made into commemorative jewelery, treasure hunting The Persias fateful voyage, Indy Almroth-Wright, BBC
Marine salvage is the process of recovering a ship and its cargo after a shipwreck or other maritime casualty. Salvage may encompass towing, re-floating a vessel, or effecting repairs to a ship, protecting the coastal environment from spillage of oil or other contaminants is a high priority. The legal significance of salvage is that a successful salvor is entitled to a reward, the amount of the award is determined subsequently at a hearing on the merits by a maritime court in accordance with Articles 13 and 14 of the International Salvage Convention of 1989. Originally, a successful salvage was one where at least some of the ship or cargo was saved, otherwise the principle of No Cure, in the 1970s, a number of marine casualties of single-skin-hull tankers led to serious oil spills. Such casualties were unattractive to salvors, so the Lloyds Open Form made provision that a salvor who acts to try to prevent environmental damage will be paid and this Lloyds initiative proved so advantageous that it was incorporated into the 1989 Convention.
All vessels have a duty to give reasonable assistance to other ships in distress in order to save life. Any offer of salvage assistance may be refused, but if it is accepted a contract automatically arises to give the successful salvor the right to a reward under the 1989 Convention. Typically, the ship and the salvor will sign up to an LOF agreement so that the terms of salvage are clear, in the Early Modern Period, diving bells were often used for salvage work. In 1658, Albrecht von Treileben was contracted by King Gustavus Adolphus of Sweden to salvage the warship Vasa, between 1663-1665 von Treilebens divers were successful in raising most of the cannon, working from a diving bell. In 1687, Sir William Phipps used a container to recover £200. The era of modern salvage operations was inaugurated with the development of the first surface supplied diving helmets by the inventors and John Deane and Augustus Siebe, in the 1830s. Royal George, a 100-gun first-rate ship of the line of the Royal Navy, sank undergoing routine maintenance work in 1782, using their new air-pumped diving helmets, they managed to recover about two dozen cannons.
Following on from success, Colonel of the Royal Engineers Charles Pasley commenced the first large scale salvage operation in 1839. His plan was to break up the wreck of Royal George with gunpowder charges, pasleys diving salvage operation set many diving milestones, including the first recorded use of the buddy system in diving, when he ordered that his divers operate in pairs. In addition, the first emergency swimming ascent was made by a diver after his air line became tangled, Pasley recovered 12 more guns in 1839,11 more in 1840, and 6 in 1841. In 1842 he recovered only one iron 12-pounder because he ordered the divers to concentrate on removing the hull rather than search for guns. Other items recovered, in 1840, included the brass instruments, silk garments of satin weave of which the silk was perfect, and pieces of leather. By 1843 the whole of the keel and the timbers had been raised
The English Channel, called simply the Channel, is the body of water that separates southern England from northern France, and links the southern part of the North Sea to the Atlantic Ocean. It is about 560 km long and varies in width from 240 km at its widest to 33.3 km in the Strait of Dover and it is the smallest of the shallow seas around the continental shelf of Europe, covering an area of some 75,000 km2. The International Hydrographic Organization defines the limits of the English Channel as follows, a line joining Isle Vierge to Lands End. The southwestern limit of the North Sea, the IHO defines the southwestern limit of the North Sea as a line joining the Walde Lighthouse and Leathercoat Point. The Walde Lighthouse is 6 km east of Calais, and Leathercoat Point is at the end of St Margarets Bay. The Strait of Dover, at the Channels eastern end, is its narrowest point and it is relatively shallow, with an average depth of about 120 m at its widest part, reducing to a depth of about 45 m between Dover and Calais.
Eastwards from there the adjoining North Sea reduces to about 26 m in the Broad Fourteens where it lies over the watershed of the land bridge between East Anglia and the Low Countries. It reaches a depth of 180 m in the submerged valley of Hurds Deep,48 km west-northwest of Guernsey. The eastern region along the French coast between Cherbourg and the mouth of the Seine river at Le Havre is frequently referred to as the Bay of the Seine. There are several islands in the Channel, the most notable being the Isle of Wight off the English coast. The coastline, particularly on the French shore, is indented, several small islands close to the coastline, including Chausey. The Cotentin Peninsula in France juts out into the Channel, whilst on the English side there is a parallel channel known as the Solent between the Isle of Wight and the mainland. The Celtic Sea is to the west of the Channel, the time difference of about six hours between high water at the eastern and western limits of the Channel is indicative of the tidal range being amplified further by resonance.
It was never defined as a border and the names were more or less descriptive. It was not considered as the property of a nation, before the development of the modern nations, British scholars very often referred to it as Gaulish and the French one as British or English. The name English Channel has been used since the early 18th century. In modern Dutch, however, it is known as Het Kanaal, later, it has been known as the British Channel or the British Sea having been called the Oceanus Britannicus by the 2nd-century geographer Ptolemy. The same name is used on an Italian map of about 1450, the Anglo-Saxon texts often call it Sūð-sǣ as opposed to Norð-sǣ
The River Clyde is a river, that flows into the Firth of Clyde in Scotland. It is the eighth-longest river in the United Kingdom, and the second-longest in Scotland, flowing through the major city of Glasgow, it was an important river for shipbuilding and trade in the British Empire. In the early medieval Cumbric language it was known as Clud or Clut, the Clyde is formed by the confluence of two streams, the Daer Water and the Potrail Water. The Southern Upland Way crosses both streams before they meet at Watermeetings to form the River Clyde proper. At this point the Clyde is only 10 kilometres from Tweeds Well, the source of the River Tweed, and 13 kilometres from the Devils Beef Tub, the source of the River Annan. From there it meanders northeastward before turning to the west, its flood plain used for major roads in the area. On the banks of the Clyde, the industrialists David Dale and Robert Owen, built their mills, the mills harness the power of the Falls of Clyde, the most spectacular of which is Cora Linn. A hydroelectric power station generates electricity here, although the mills are now a museum.
Between the towns of Motherwell and Hamilton the course of the river has altered to create an artificial loch within Strathclyde Park. Part of the course can still be seen, and lies between the island and the east shore of the loch. The river flows through Blantyre and Bothwell, where the ruined Bothwell Castle stands on a defensible promontory, past Uddingston and into the southeast of Glasgow the river begins to widen, meandering a course through Rutherglen and Dalmarnock. From there, it flows past the shipbuilding heartlands, through Govan, Whiteinch and Clydebank, all of which housed major shipyards, of which only two remain. The river flows out west of Glasgow, past Renfrew, opposite, on the south shore, the river continues past the last Lower Clyde shipyard at Port Glasgow to Greenock where it reaches the Tail of the Bank as the river merges into the Firth of Clyde. At the mouth of the River Clyde there has been a significant issue of oxygen depletion in the water column, the valley of the Clyde was the focus for the G-BASE project from the British Geological Survey in the summer of 2010.
The success of the Clyde at the beginning of the Industrial Revolution was driven by the location of Glasgow and cotton trade began the drive in the early 18th century. However, the shallow Clyde was not navigable for the largest ocean-going ships, in 1768 John Golborne advised the narrowing of the river and the increasing of the scour by the construction of rubble jetties and the dredging of sandbanks and shoals. A particular problem was the division of the river into two channels by the Dumbuck shoal near Dumbarton. After James Watts report on this in 1769, a jetty was constructed at Longhaugh Point to block off the southern channel and this being insufficient, a training wall called the Lang Dyke was built in 1773 on the Dumbuck shoal to stop water flowing over into the southern channel