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A sea trial is the testing phase of a
watercraft Watercraft, also known as water vessels or waterborne vessels, are vehicles A vehicle (from la, vehiculum) is a machine A machine is any physical system with ordered structural and functional properties. It may represent human-made or ...
(including
boat A boat is a watercraft Watercraft, also known as water vessels or waterborne vessels, are vehicles A vehicle (from la, vehiculum) is a machine A machine is any physical system with ordered structural and functional properties. It m ...

boat
s,
ship A ship is a large watercraft Watercraft, also known as water vessels or waterborne vessels, are vehicles A vehicle (from la, vehiculum) is a machine A machine is any physical system with ordered structural and functional propertie ...

ship
s, and
submarine A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. It is also sometimes used historically or colloquially to refer to remotely operated ...

submarine
s). It is also referred to as a " shakedown cruise" by many naval personnel. It is usually the last phase of construction and takes place on open water, and it can last from a few hours to many days. Sea trials are conducted to measure a vessel's performance and general
seaworthiness Seakeeping ability or seaworthiness is a measure of how well-suited a watercraft is to conditions when underway. A ship or boat which has good seakeeping ability is said to be very seaworthy and is able to operate effectively even in high sea state ...
. Testing of a vessel's speed, maneuverability, equipment and safety features are usually conducted. Usually in attendance are technical representatives from the builder (and from builders of major systems), governing and certification officials, and representatives of the owners. Successful sea trials subsequently lead to a vessel's
certification Certification is the formal attestation or confirmation of certain characteristics of an object, person, or organization. This confirmation is often, but not always, provided by some form of external review, education, assessment, or audit ...

certification
for commissioning and acceptance by its owner. Although sea trials are commonly thought to be conducted only on new-built vessels (referred by shipbuilders as 'builders trials'), they are regularly conducted on commissioned vessels as well. In new vessels, they are used to determine conformance to construction specifications. On commissioned vessels, they are generally used to confirm the impact of any modifications. Sea trials can also refer to a short test trip undertaken by a prospective buyer of a new or used vessel as one determining factor in whether to purchase the vessel.


Typical trials

Sea trials are fairly standardized using technical bulletins published by ITTC,
SNAME The Society of Naval Architects and Marine Engineers (SNAME) is a global professional society A professional association (also called a professional body, professional organization, or professional society) usually seeks to advocacy, further ...
, BMT, regulatory agencies or the owners. They involve demonstrations and tests of the ship's systems and performance.


Speed trial

In a speed trial the vessel is ballasted or loaded to a predetermined draft and the propulsion machinery is set to the contracted maximum service setting, usually some percentage of the machinery's maximum continuous rating (ex: 90% MCR). The ship's heading is adjusted to have the wind and tide as close to bow-on as possible. The vessel is allowed to come to speed and the speed is continuously recorded using
differential GPS A Differential Global Positioning System (DGPS) is an enhancement to the Global Positioning System The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States gove ...
. The trial will be executed with different speeds including service (design) and maximum speed. The ship is then turned through 180° and the procedure is followed again. This reduces the impact of wind and tide. The final "Trials Speed" is determined by averaging all of the measured speeds during each of the runs. This process may be repeated in various sea states.


Crash stop

To test a crash stop, the vessel is ballasted or loaded to a predetermined draft and the propulsion machinery is set to the contracted maximum service setting, usually some percentage of the machinery's maximum continuous rating. The trial begins once the order to "Execute Crash Stop" is given. At this point the propulsion machinery is set to full-astern and the helm is put hard-over to either port or starboard. The speed, position and heading are continuously recorded using differential GPS. The final time to stop (i.e.: ship speed is 0 knots) track line, drift (distance traveled perpendicular to the original course) and advance (distance traveled along the original course line) are all calculated. The trial may be repeated at various starting speeds.


Endurance

During endurance trials the vessel is ballasted or loaded to a predetermined draft and the propulsion machinery is set to the contracted maximum service setting, usually some percentage of the machinery's maximum continuous rating. The fuel flow, exhaust and cooling water temperatures and ship's speed are all recorded.


Maneuvering trials

Maneuvering trials involve a number of trials to determine the maneuverability and directional stability of the ship may be conducted. These include a direct and reverse spiral manoeuvres, zig-zag, and lateral thruster use.


Seakeeping

Seakeeping trials were used exclusively for passenger ships, but are now used in a variety of vessels. They involve measurements of
ship motions Ship motions are defined by the six degrees of freedom Degrees of Freedom (often abbreviated df or DOF) refers to the number of independent variables or parameters of a system. In various scientific fields, the word "freedom" is used to descri ...
in various
sea state In oceanography Oceanography (from the Ancient Greek Ancient Greek includes the forms of the used in and the from around 1500 BC to 300 BC. It is often roughly divided into the following periods: (), Dark Ages (), the period () ...
s, followed by a series of analyses to determine comfort levels, likelihood of sea sickness and hull damage. Trials are usually protracted in nature due to the unpredictability of finding the correct sea state, and the need to conduct the trials at various headings and speeds.


Noteworthy sea trials

* – While steaming at high speeds, severe vibration was noted at the
stern The stern is the back or aft Aft :''For the acronym, see AFT (disambiguation).'' Aft, in naval A navy, naval force, or maritime force is the branch of a Nation's armed forces A military, also known collectively as armed forces, ...

stern
during her sea trials. This prompted her builder,
John Brown & Company John Brown and Company of Clydebank was a Scottish Naval architecture, marine engineering and shipbuilding firm. It built many notable and world-famous ships including , , , , , and the ''Queen Elizabeth 2 (ship), Queen Elizabeth 2''. At its ...
, to reinforce that area before acceptance by
Cunard Cunard Line is a British cruise line based at Carnival House at Southampton, England, operated by Carnival Corporation & plc#Carnival United Kingdom, Carnival UK and owned by Carnival Corporation & plc. Since 2011, Cunard and its three shi ...
. * – During sea trials, vibration was noted at the ship's stern. The stern was reinforced, accepted by her owners Compagnie Générale Transatlantique, and continued onto her
maiden voyage The maiden voyage of a ship A ship is a large watercraft Watercraft, also known as water vessels or waterborne vessels, are vehicles A vehicle (from la, vehiculum) is a machine A machine is any physical system with ordered ...
. The vibration was severe enough to necessitate relocating Tourist Class passengers and some crew members with cabins near the affected area. The problem was subsequently resolved by changing her
propellers A propeller is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral, that, when rotated, exerts linear thrust Thrust is a reaction Reaction may refer to a process or to a response to an actio ...
to four-bladed ones from the original three-bladed ones. * – At the start of World War II, it was decided that ''Queen Elizabeth'' was so vital to the war effort that she must not have her movements tracked by German spies operating in the Clydebank area. Therefore, an elaborate ruse was fabricated involving her sailing to Southampton to complete her fitting out. Another factor prompting ''Queen Elizabeth''s departure was the necessity to clear the fitting out berth at the shipyard for the battleship ,Maxtone-Graham, John. ''The Only Way to Cross''. New York: Collier Books, 1972, pp. 358–60 which was in need of its final fitting-out. Only the berth at John Brown could accommodate the ''King George V''-class battleship's needs.One major factor that limited the ship's secret departure date was that there were only two spring tides that year that would see the water level high enough for ''Queen Elizabeth'' to leave the Clydebank shipyard, and German intelligence were aware of this fact. A minimal crew of four hundred were assigned for the trip; most were transferred from for a short coastal voyage to Southampton. Parts were shipped to Southampton, and preparations were made to move the ship into the King George V graving dock when she arrived. The names of Brown's shipyard employees were booked to local hotels in Southampton to give a false trail of information and Captain John Townley was appointed as her first
master Master or masters may refer to: Ranks or titles *Ascended master Ascended masters in the Ascended Master Teachings of a number of movements in the theosophical tradition are believed to be spiritually enlightened beings who in past incarn ...

master
. Townley had previously commanded ''Aquitania'' on one voyage, and several of Cunard's smaller vessels before that. Townley and his hastily signed on crew of four hundred Cunard personnel were told by a company representative before they left to pack for a voyage where they could be away from home for up to six months.''Floating Palaces.'' (1996) A&E. TV Documentary. Narrated by Fritz WeaverBy the beginning of March 1940, ''Queen Elizabeth'' was ready for her secret voyage. The Cunard colours were painted over with
battleship grey Variations of gray or grey include achromatic grayscale shades, which lie exactly between white and black, and nearby colors with low colorfulness. A selection of a number of these various colors is shown below. Chart of computer web color ...
, and on the morning of 3 March, ''Queen Elizabeth'' quietly left her moorings in the Clyde and proceeded out of the river to sail further down the coast, where she was met by the
King's Messenger The Corps of Queen's Messengers are courier A courier is a company, an employee of that company or a person who delivers a message, package or letter from one place or person to another place or person. Duties and functions Couriers are d ...
, who presented sealed orders directly to the captain. While waiting for the Messenger, the ship was refuelled; adjustments to the ship's compass and some final testing of equipment were also carried out before she sailed to her secret destination.Captain Townley discovered that he was to take the ship directly to New York in the then neutral United States without stopping, or even slowing to drop off the Southampton
harbour pilot A maritime pilot, marine pilot, harbor pilot, port pilot, ship pilot, or simply pilot, is a mariner who maneuvers ships through dangerous or congested waters, such as harbors or river mouths. Maritime pilots are largely regarded as skilled profe ...
who had embarked on at Clydebank, and to maintain strict radio silence. Later that day, at the time when she was due to arrive at Southampton, the city was bombed by the
Luftwaffe The ''Luftwaffe'' () was the aerial-warfare branch of the German ''Wehrmacht The ''Wehrmacht'' (, ) was the unified armed forces of Nazi Germany from 1935 to 1945. It consisted of the German Army (1935–1945), ''Heer'' (army), th ...
. After a zigzagged crossing taking six days to avoid German U-boats, ''Queen Elizabeth'' had still crossed the Atlantic at an average speed of 26 knots. In New York she found herself moored alongside both ''Queen Mary'' and the French Line's , the only time all three of the world's largest liners would be berthed together. Captain Townley received two telegrams on his arrival, one from his wife congratulating him and the other from Queen Elizabeth thanking him for the vessel's safe delivery. The ship was then secured so that no one could board her without prior permission, including port officials. * – Her trials were conducted over two periods, September 25–29, 2003 and November 7–11, 2003, each lasting four days at sea, shuttling between the islands of Belle-Ile and L'
ile d'Yeu Ile may refer to: * iLe, a Puerto Rican singer * Ile District (disambiguation), multiple places * Ilé-Ifẹ̀, an ancient Yoruba city in south-western Nigeria * Interlingue (ISO 639:ile), a planned language * Isoleucine, an amino acid * Another n ...
off the French coast. On board for each set of trials were 450 people, including engineers, technicians, owner and insurance company representatives, and crew.Plisson, Philip; Queen Mary 2: The Birth of a Legend; Harry N. Abrams, Inc, Publishers; 2004; ppg. 24- 25 * – Lost during deep sea diving tests on April 10, 1963.


References

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