Feature 1 | CRUISESHIP TECHNOLOGY Maximum squats for Victoria
Up to November 2008, Dr Bryan Barrass* had collected a database of 104 vessels that had recently gone aground, attributable wholly or in part to ship squat. Here, Dr Barrass offers his views on what could happen, on the basis of what has happened, in the case of a particular ship - Queen Victoria. Forewarned is forearmed.
a reasonable rate of stowage, in a seaworthy vessel, at a predetermined speed, on a given radius of action, as cheaply as possible, all in conjunction with a General Arrangement suited to the ship’s trade. Not my words, but those of Ross
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Munro-Smith (senior lecturer at Newcastle University) in the mid-1960s. But what happens when the new ship moves from a deep-water situation to shallow waters? Once a new ship is designed, built and
delivered, the ship-handling challenge for retaining her seaworthiness becomes the responsibility of officers on watch on the vessel’s bridge. Ship design and ship performance must
be closely interlinked. Ship performance can become an issue where shallow water
*Dr Bryan Barrass worked as a ship draughtsman for 11 years at Swan Hunters Shipyard in Wallsend. In 1963, he then became a lecturer in naval architecture in Sunderland. From 1967 to 1993, he worked at Liverpool John Moores University, lecturing to maritime degree students, masters, mates, and marine engineers. In 1993 he retired from full-time work. He became a visiting lecturer and writer of six books on ship stability, ship design and ship performance. His interest in ship squat began in April 1972, starting on research for his Ph.D. degree. Dr Barrass has supplied squat information and details
to 21 countries worldwide. He has worked with many Port Authorities, including PLA, Milford Haven PA, Liverpool PA, Humberside PA, Tyne PA, Truro PA, Newhaven PA, Bordeaux PA, Klaipeda PA, Nantes PA and Hamburg PA. He has expressed his gratitude for the help and
encouragement given by: Captain Frank L Main, head of Maritime Studies Department, Liverpool Polytechnic; Dr Richard B Whittington, reader in Civil Engineering Department, Liverpool University; Captain Sergio Battera, vice chief (retired) pilot, Co-operation of Venice Port & Estuary Authority.
The Naval Architect February 2009
t has been said that the problem for a naval architect is to design a new ship that will carry a certain deadweight, at
less risk of a foreign-going vessel grounding. Because of the danger of grounding, below H/T values of 1.10 there are very few recorded measured squats for full sized ships. Te main aim and objective of this article
is to help prevent ships going aground because of ship squat effects. Based on my 36-plus years research on this topic, it is to give readers of Te Naval Architect an awareness and understanding of the dangers of ship squat.
Queen Victoria.
conditions exist in open water and in confined channels. Especially in this new Millennium, the phenomenon known as ship squat becomes much more important to consider. Up to November 2008, I have a database of
104 vessels that have recently gone aground, attributable wholly or in part, due to squat. This warns not what could happen, but what has happened. It could happen with the Queen Victoria (delivered in December 2007). Forewarned is to be forearmed. Squat exists when a 3-D body (the ship)
proceeds through a 3-D medium (the water). Tey are connected by a 3-D coefficient (the block coefficient or CB). Consequently, most of my squat formulae contain the component of CB. First, may I point out that it is not my
intention or aim to advise harbour masters and ship pilots how to handle ships. My background, as a humble Naval Architect, certainly does not permit me to even think about it. However, I wish to offer some guidance on the problems of ship squat in shallow waters. Troughout this article, the ratio of the
water depth (H) to the ship’s static draught (T) at amidships is for a range of 1.10 to 1.40. Above an H/T of 1.40 there is a great deal
Recent evolution The 334m length passenger liner QM2 delivered in 2003, is longer than the Statue of Liberty, the Tower of London and the Coliseum in Rome. In April 2006, ‘Freedom of the Seas’ was
delivered. She has an Lbp of 303.2m and a breadth moulded of 38.6m with a draught moulded of 8.50m. On 10 October 2007, Internet search
engines gave information that a new 92,000 tonne cruiseship would be entering service on the high seas in Autumn 2010. Her name is to be Queen Elizabeth. She will carry 2092 Passengers, with over 1000 Crew. Her first cost will be of the order of $700 million. Even larger will be the Genesis project
ships for the Royal Caribbean Shipping Line. Te order was placed in 2006 and delivery is due in the fall of 2009. Here, length is to be 360m with a beam of 47m. Te complement is to be 5400 passengers, plus officers and crew: certainly a mammoth ship. Back to the present day: consider now
the phenomena of ship squat for the Queen Victoria in shallow waters, by way of text, tables and graphics. Table 1 gives the general particulars for this vessel.
What is ship squat? When a ship proceeds through water, she pushes water ahead of her. In order not
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