Sea trial

A sea trial is the testing phase of a watercraft (including boats, ships, and submarines). 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. 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 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

MS Sabine Howaldt - Kieler Förde - im Mai 1958 auf Probefahrt 1
Nobiskrug new ship Sabine Howaldt on sea trials in the Kiel Fjord in May 1958

Sea trials are fairly standardized using technical bulletins published by ITTC, SNAME, 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. 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.


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.[1]


Seakeeping trials were used exclusively for passenger ships, but are now used in a variety of vessels. They involve measurements of ship motions in various sea states, 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.[2]

Noteworthy sea trials

  • RMS Lusitania – While steaming at high speeds, severe vibration was noted at the stern during her sea trials. This prompted her builder, John Brown & Company, to reinforce that area before acceptance by Cunard.[3]
  • SS Normandie – 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 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 to four-bladed ones from the original three-bladed ones.[4][5]
  • RMS Queen Elizabeth – 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.[6] Another factor prompting Queen Elizabeth's departure was the necessity to clear the fitting out berth at the shipyard for the battleship HMS Duke of York,[6] 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,[6] and German intelligence were aware of this fact. A minimal crew of four hundred were assigned for the trip; most were transferred from Aquitania for a short coastal voyage to Southampton.[6] Parts were shipped to Southampton, and preparations were made to move the ship into the King George V graving dock when she arrived.[6] 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. Townley had previously commanded the 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.[7]
    By the beginning of March 1940, Queen Elizabeth was ready for her secret voyage. The Cunard colours were painted over with battleship grey, and on the morning of 3 March, the QE quietly left her moorings in the Clyde and proceeded out of the river to sailed further down the coast, where she was met by the King's Messenger,[6] 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 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.[6] 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 Normandie, the only time all three of the world's largest liners would be berthed together.[6] Captain Townley received two telegrams on his arrival, one from his wife congratulating him and the other from Her Majesty 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.[6]
  • RMS Queen Mary 2 – 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 off the French coast. On board for each set of trials were 450 people, including engineers, technicians, owner and insurance company representatives, and crew.[8]
  • USS Thresher (SSN-593) – Lost during deep sea diving tests on April 10, 1963.


  1. ^ Lewis, Principles of Naval Architecture , Volume II, Section 15, p. 316 (Maneuvering Trials and Performance
  2. ^ Lewis, Principles of Naval Architecture , Volume II, Section 7.3, p. 140 (Seakeeping Performance Criteria and Seaway Response).
  3. ^ Ballard Robert F. & Spencer Dunmore (with paintings by Ken Marschall); Exploring the Lusitania: Probing the Mysteries of the Sinking that Changed History; Warner/ Madison Press; 1995; ppg. 22- 23
  4. ^ Ballard Robert F. & Rich Archbold (with paintings by Ken Marschall); Lost Liners; ppg 168, 170
  5. ^ Braynard, Frank; Picture History of the Normandie; Dover Publications, Inc., 1987; pg. 16–17
  6. ^ a b c d e f g h i Maxtone-Graham, John. The Only Way to Cross. New York: Collier Books, 1972, pp. 358–60
  7. ^ Floating Palaces. (1996) A&E. TV Documentary. Narrated by Fritz Weaver
  8. ^ Plisson, Philip; Queen Mary 2: The Birth of a Legend; Harry N. Abrams, Inc, Publishers; 2004; ppg. 24- 25

AUV (Autonomous Underwater Vehicle) - 150 is an unmanned underwater vehicle (UUV) being developed by Central Mechanical Engineering Research Institute (CMERI) scientists in Durgapur in the Indian state of West Bengal. The project is sponsored by the Ministry of Earth Sciences and has technical assistance from IIT-Kharagpur.The vehicle was built with the intent of coastal security like mine counter-measures, coastal monitoring and reconnaissance. AUV 150 can be used to study aquatic life, for mapping of sea-floor and minerals along with monitoring of environmental parameters, such as current, temperature, depth and salinity. It can also be useful in cable and pipeline surveys.

It is built to operate 150 metres under the sea and have cruising speed of up to four knots.

Beetle Cat

A Beetle Cat is a 12-foot-4-inch (3.76 m) catboat first built in 1920 in New Bedford, Massachusetts by members of the Beetle family. Over 4,000 have been built. Beetle, Inc., now in Wareham, Massachusetts, is the sole builder of Beetle Cat boats.

Famous owners include or have included Senator John Kerry, Jacqueline Onassis, who had one shipped to Greece in 1969 for John F. Kennedy Jr. and Caroline Kennedy to learn sailing in, Steven Spielberg and Calvin Klein.

A new Beetle 14 catboat, with bench seating, accommodates four adults and has 80% more cockpit interior space. Designed by Bill Sauerbrey in 2006/2007, it underwent a sea trial in late April 2007.

Chinese aircraft carrier Liaoning

Liaoning (16; Chinese: 辽宁舰; pinyin: Liáoníng Jiàn) is a Chinese Type 001 aircraft carrier. The first aircraft carrier commissioned into the People's Liberation Army Navy Surface Force, she is classified as a training ship, intended to allow the Navy to experiment, train and gain familiarity with aircraft carrier operations.

Originally laid down in 1985 for the Soviet Navy as the Kuznetsov-class aircraft cruiser Riga, she was launched on 4 December 1988 and renamed Varyag in 1990. After the dissolution of the Soviet Union in 1991, construction was halted and the ship was put up for sale by Ukraine. The stripped hulk was purchased in 1998 and towed to the Dalian naval shipyard in northeast China.

The ship was rebuilt and commissioned into the People's Liberation Army Navy (PLAN) as Liaoning on 25 September 2012. Its Chinese ship class designation is Type 001. In November 2016, the political commissar of Liaoning, Commodore Li Dongyou, stated that Liaoning was combat ready.


FCS-3 is an integrated naval weapons system developed by the Japanese Defense Ministry for the Japan Maritime Self-Defense Force.

This system is composed of weapon-direction and fire-control subsystem and multi-function radar subsystem. The multi-function radar subsystem adopted active electronically scanned array (AESA) technology, and there are two sets of antennas: the larger one is a C-band radar for surveillance and tracking, the smaller one is a X-band radar as a fire-control radar.After a prolonged sea trial on board JS Asuka, this system was introduced in 2007 on the JS Hyūga (DDH-181). The enhanced version, FCS-3A, was employed on the Akizuki-class destroyers., and limited-function version, OPS-50, was also delivered for the Izumo-class helicopter destroyers. The fire-control function are omitted in the OPS-50 system, so they have only one set of antennas operating C-band.The Asahi-class destroyer features an FCS-3A radar that uses Gallium nitride technology to improve its performance.


Fitting-out, or "outfitting”, is the process in shipbuilding that follows the float-out of a vessel and precedes sea trials. It is the period when all the remaining construction of the ship is completed and readied for delivery to her owners. Since most of the fitting-out process is interior work, this stage can overlap with latter stages, such as the sea trials.

Guided missile destroyer

A guided-missile destroyer is a destroyer designed to launch guided missiles. Many are also equipped to carry out anti-submarine, anti-air, and anti-surface operations. The NATO standard designation for these vessels is DDG. Nations vary in their use of destroyer D designation in their hull pennant numbering, either prefixing or dropping it altogether. The U.S. Navy has adopted the classification DDG in the American hull classification system.

In addition to the guns, a guided-missile destroyer is usually equipped with two large missile magazines, usually in vertical-launch cells. Some guided-missile destroyers contain powerful radar systems, such as the United States’ Aegis Combat System, and may be adopted for use in an anti-missile or ballistic-missile defense role. This is especially true of navies that no longer operate cruisers, so other vessels must be adopted to fill in the gap.

HMS Vanguard (23)

HMS Vanguard was a British fast battleship built during the Second World War and commissioned after the end of the war. She was the biggest and fastest of the Royal Navy's battleships, the last battleship to be launched in the world, and the only ship of her class.

The Royal Navy anticipated being outnumbered by the combined German and Japanese battleships in the early 1940s, and had therefore started building the Lion-class battleships. However the time-consuming construction of the triple-16-inch turrets for the Lion-class would delay their completion until 1943 at the earliest. The British had enough 15-inch (381 mm) guns and turrets in storage to allow one ship of a modified Lion-class design with four twin-15-inch turrets to be completed faster than the Lion-class vessels that had already been laid down.

Work on Vanguard was started and stopped several times during the war, and her design was revised several times during her construction to reflect war experience. These stoppages and changes prevented her from being completed before the end of the war.

Vanguard's first task after completing her sea trial at the end of 1946 was, early the next year, to convey King George VI and his family on the first Royal Tour of South Africa by a reigning monarch. While refitting after her return, she was selected for another Royal Tour of Australia and New Zealand in 1948. This was cancelled due to King George's declining health and Vanguard briefly became flagship of the Mediterranean Fleet in early 1949. After her return home in mid-1949, she became flagship of the Home Fleet Training Squadron. Throughout her career, the battleship usually served as the flagship of any unit to which she was assigned. During the early 1950s, Vanguard was involved in a number of training exercises with NATO forces. In 1953 she participated in Queen Elizabeth II's Coronation Review. While she was refitting in 1955, the Admiralty announced that the ship was going to be put into reserve upon completion of the work. Vanguard was sold for scrap and was broken up beginning in 1960.

INS Kalvari (S21)

INS Kalvari (S21) is the first of the six Kalvari-class submarine currently in service with the Indian Navy. It is a diesel-electric attack submarine which is designed by DCNS (French naval defence and energy company) and was manufactured at Mazagon Dock Limited in Mumbai.

John Campbell (Royal Navy officer)

Vice-Admiral John Campbell (1720–1790) was born in the parish of Kirkbean in Kirkcudbrightshire, Scotland. Campbell was a British naval officer, navigational expert and colonial governor.

Campbell joined the Royal Navy at an early age and sailed around the world in 1740 on the Centurion. He later became known as a navigational expert, and was from 1782 to his death Governor and Commander-in-Chief in Newfoundland.

Project Deep Spill

Project Deep Spill was the first intentional deepwater oil spill, in order to study how crude oil behaved in-depth. A Joint Industry Project comprising 23 oil companies and the Minerals Management Service performed a sea trial in late June 2000 in the Helland Hansen region of the Norwegian Sea. The trial made several releases of varying combinations of crude oil (750 barrels), marine diesel, methane (18 cubic metres) and nitrogen gas from the seabed at 840 metres below sea-level.

Seahorse ROUV

Seahorse (Hai-Ma or Haima, 海马) remotely operated underwater vehicle (ROUV) is a Chinese ROUV developed by Shanghai Jiao Tong University (SJTU), and it received state certification in mid 2014.Seahorse ROUV program begun in 2008 and Professor Ma Xia-Fei (马厦飞) is the program manager, and the general designers of Seahorse ROUV are Professor Lian Lian (连琏) and Professor Ren Ping (任平). Seahorse ROUV is designed to dive to a maximum depth of forty-five hundred meters, and from April 20, 2014 thru April 22, 2014, Seahorse UAV conducted more than seventeen dives in three different phases of sea trial, reaching the maximum designed depth to 4502 meter. After the successful sea trials, state certification is received soon after, and there are plans to develop different models based on the original Seahorse. Seahorse ROUV is designed to perform a variety of research missions and it is equipped with sonar, cameras, mechanical arms, and in addition to research missions, Seahorse ROUV is also capable of performing maintenance work on scientific equipment on seabed. Seahorse utilizes modular design concept to enable different tools to be replaced rapidly based on mission needs while sharing a common chassis. During deployment, Seahorse ROUV is usually carried by Chinese scientific research vessel Ocean 6 (Hai-Yang or Haiyang 6, 海洋6号), though it can also be carried by other Chinese ships equipped to handle ROUVs.

Shakedown (testing)

A shakedown is a period of testing or a trial journey undergone by a ship, aircraft or other craft and its crew before being declared operational. Statistically, a proportion of the components will fail after a relatively short period of use, and those that survive this period can be expected to last for a much longer, and more importantly, predictable life-span. For example, if a bolt has a hidden flaw introduced during manufacturing, it will not be as reliable as other bolts of the same type.

Ship commissioning

Ship commissioning is the act or ceremony of placing a ship in active service, and may be regarded as a particular application of the general concepts and practices of project commissioning. The term is most commonly applied to the placing of a warship in active duty with its country's military forces. The ceremonies involved are often rooted in centuries old naval tradition.

Ship naming and launching endow a ship hull with her identity, but many milestones remain before she is completed and considered ready to be designated a commissioned ship. The engineering plant, weapon and electronic systems, galley, and multitudinous other equipment required to transform the new hull into an operating and habitable warship are installed and tested. The prospective commanding officer, ship's officers, the petty officers, and seamen who will form the crew report for training and intensive familiarization with their new ship.

Prior to commissioning, the new ship undergoes sea trials to identify any deficiencies needing correction. The preparation and readiness time between christening-launching and commissioning may be as much as three years for a nuclear powered aircraft carrier to as brief as twenty days for a World War II landing ship. USS Monitor, of American Civil War fame, was commissioned less than three weeks after launch.

Type 001A aircraft carrier

The Type 001A aircraft carrier is a first generation Chinese aircraft carrier that was launched on 26 April 2017 for the People's Liberation Army Navy (PLAN) of China. It is the country's second aircraft carrier after the completion of Liaoning, and the first built domestically.

Type 052D destroyer

The Type 052D destroyer (NATO code name Luyang III class, or Kunming class after the lead ship) is a class of guided missile destroyers being deployed by the Chinese People's Liberation Army Navy Surface Force. Currently it is being built at two different Chinese shipyards.

After the Type 052C destroyer (NATO code name Luyang II class, or Lanzhou class after the lead ship), two new hulls were spotted under construction at Changxingdao-Jiangnan Shipyard (JNCX) in August 2012. According to imagery, they were armed with a new 130 mm main gun and new AESA radar system. Altogether nine vessels of this class are now fitting out or under construction, two vessels are on sea trial and eleven vessels are active.

Despite being only halfway through the 052D production run, the PLAN has begun serial construction of the class successor, the larger and more powerful Type 055 destroyer. The Type 052D Luyang destroyers are not quite as large and capable as their latest Type 055 program. They are, nonetheless, modern and competent warships.

USCGC Matagorda (WPB-1303)

USCGC Matagorda (WPB-1303) is an Island-class patrol boat of the United States Coast Guard. She was commissioned 24 April 1986. Matagorda was one of eight of the 110-foot cutters to be modified under the Integrated Deepwater System Program aka. "Deepwater" to 123-foot. She was taken out of service about December 2006 due to problems with the Deepwater conversion.

USS Gravely

USS Gravely (DDG-107) is an Arleigh Burke-class guided missile destroyer in the United States Navy. She is named after Vice Admiral Samuel L. Gravely, Jr.Gravely is the 57th destroyer in her class. She was authorized on 13 September 2002 and her keel was laid down on 26 November 2007 at Northrop Grumman Shipbuilding's Ingalls Shipbuilding shipyard in Pascagoula, Mississippi. Gravely was launched on 30 March 2009. She successfully completed sea trial in June 2010.Alma B.C. Gravely, Admiral Gravely's widow, christened Gravely, Northrop Grumman’s 27th Aegis guided missile destroyer, on 16 May 2009. Retired Navy Adm. J. Paul Reason was the principal speaker at the ceremony, which was held at Northrop’s facility in Pascagoula.Gravely was commissioned at Wilmington, North Carolina on 20 November 2010. She is currently the Flagship of Standing NATO Maritime Group One.

USS Zumwalt

USS Zumwalt (DDG-1000) is a guided missile destroyer of the United States Navy. She is the lead ship of the Zumwalt class and the first ship to be named for Admiral Elmo Zumwalt. Zumwalt has stealth capabilities, having a radar cross-section similar to a fishing boat despite her large size. On 7 December 2015, Zumwalt began her sea trial preparatory to joining the Pacific Fleet. The ship was commissioned in Baltimore on 15 October 2016. She is homeported in San Diego, California.

You're in the Navy Now

You're in the Navy Now is a Hollywood film released in 1951 by Twentieth Century Fox about the United States Navy in the first months of World War II. Its initial release was titled USS Teakettle. Directed by Henry Hathaway, the film is a comedy starring Gary Cooper as a new officer wanting duty at sea but who is instead assigned to an experimental project without much hope of success.

Filmed in black-and-white aboard PC-1168, an active Navy patrol craft, You're in the Navy Now featured the film debuts of Charles Bronson, Jack Warden, Lee Marvin, and Harvey Lembeck in minor roles as crewmen. Screenwriter Richard Murphy was nominated by the Writers Guild of America for "Best Written American Comedy", basing his script on an article written by John W. Hazard in The New Yorker. Hazard, a professional journalist and naval reservist, had served during World War II as executive officer of the PC-452, a similar craft that served in 1943-44 as a test bed for steam turbine propulsion.

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