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Keel

The keel is the bottom-most longitudinal structural element on a watercraft. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. The laying of the keel is often the initial step in the construction of a ship. In the British and American shipbuilding traditions, this event marks the beginning date of a ship's construction.[1]

Keel laid for the USS United States in drydock

Etymology edit

The word "keel" comes from Old English cēol, Old Norse kjóll, = "ship" or "keel". It has the distinction of being regarded by some scholars as the first word in the English language recorded in writing, having been recorded by Gildas in his 6th century Latin work De Excidio et Conquestu Britanniae, under the spelling cyulae (he was referring to the three ships that the Saxons first arrived in).[2][3]

Carina is the Latin word for "keel" and is the origin of the term careen (to clean a keel and the hull in general, often by rolling the ship on its side). An example of this use is Careening Cove, a suburb of Sydney, Australia, where careening was carried out in early colonial days.

History edit

Origins edit

 
Carvel-built hull construction (right) lines planks up edge to edge

The use of a keel in sailing vessels goes back to antiquity. The wreck of an ancient Greek merchant ship known as the Kyrenia ship establishes the origin of the keel at least as far back as 315 BC.[4][page needed] The Uluburun shipwreck (c. 1325 BC) had a rudimentary keel, but it may have been more of a center plank than a keel.[5]

Construction styles edit

Frame first edit

In carvel-built hulls, construction began with the laying of the keel, followed by the stern and stem. Frames were set up afterward, set at key points along the keel. Later, the keelson was attached to the keel, either bolted or with treenails.[6]

Plank first edit

Structural keels edit

A structural keel is the bottom-most structural member around which the hull of a ship is built. The keel runs along the centerline of the ship, from the bow to the stern. The keel is often the first part of a ship's hull to be constructed, and laying the keel, or placing the keel in the cradle in which the ship will be built may mark the start time of its construction. Large, modern ships are now often built in a series of pre-fabricated, complete hull sections rather than being built around a single keel, so the shipbuilding process commences with the cutting of the first sheet of steel.[7]

The most common type of keel is the "flat plate keel", and this is fitted in the majority of ocean-going ships and other vessels. A form of keel found on smaller vessels is the "bar keel", which may be fitted in trawlers, tugs, and smaller ferries. Where grounding is possible, this type of keel is suitable with its massive scantlings, but there is always a problem of the increased draft with no additional cargo capacity. If a double bottom is fitted, the keel is almost inevitably of the flat plate type, bar keels often being associated with open floors, where the plate keel may also be fitted.[citation needed]

Hydrodynamic keels edit

Hydrodynamic keels have the primary purpose of interacting with the water and are typical of certain sailboats. Fixed hydrodynamic keels have the structural strength to support the weight of the boat.[8]

 
Sailing yacht with a fin keel
 
Lateral resistance effect of a sailing keel
 
Righting effect of a keel, where A is the center of buoyancy and G is the centre of gravity (hypothetical example).

Sailboat keels edit

In sailboats, keels serve two purposes: 1) as an underwater foil to minimize the lateral motion of the vessel under sail (leeway) and 2) as a counterweight to the lateral force of the wind on the sail(s) that causes rolling to the side (heeling). As an underwater foil, a keel uses the forward motion of the boat to generate lift to counteract the leeward force of the wind. Related foils include centerboards and daggerboards, which do not have the secondary purpose of being a counterweight. As counterweight, a keel increasingly offsets the heeling moment with increasing angle of heel.

Moveable sailboat keels may pivot (a swing keel),[9] retract upwards (retracting keel),[10] or swing sideways in the water (canting keels) to move the ballasting effect to one side and allow the boat to sail in a more upright position.[11]

See also edit

Notes edit

  1. ^ Man, Myth & Magic: The Illustrated Encyclopedia of Mythology, Religion and the Unknown. M. Cavendish. 1995. p. 2364. ISBN 9781854357311.
  2. ^ "Gildas, The Ruin of Britain &c. (1899). pp. 4–252. The Ruin of Britain".
  3. ^ G. W. Whittaker (1970). Collected Essays. Ayer Publishing. p. 44. ISBN 0-8369-1636-0.
  4. ^ Katzev, Susan Womer; Swiny, Helena Wylde (2022). The Kyrenia Ship Final Excavation Report: Volume I - History of the Excavation, Amphoras, Pottery and Coins as Evidence for Dating. Oxbow Books. ISBN 9781785707520.
  5. ^ Pulak, Cemal (1998). "The Uluburun Shipwreck: An Overview". The International Journal of Nautical Archaeology. 27 (3): 210. doi:10.1111/j.1095-9270.1998.tb00803.x.
  6. ^ Adams, Jonathan R. (2013). A Maritime Archaeology of Ships: Innovation and Social Change in Late Medieval and Early Modern Europe: A Maritime Archaeology of Early Modern Europe. Oxford: Oxbow Books. ISBN 978-1-78297-047-7. OCLC 862401040.|p=76}}
  7. ^ Walton, Thomas (1901). Know Your Own Ship. London: Charles Griffin & Company. pp. 57–60. ISBN 9783861951643.
  8. ^ Streiffert, Bo (September 1994). Modern Boat Maintenance: The Complete Fiberglass Boat Manual. Sheridan House, Inc. p. 173. ISBN 978-0-924486-71-5.
  9. ^ Spurr, Daniel (2004-07-02). Your First Sailboat: How to Find and Sail the Right Boat for You. McGraw Hill Professional. p. 10. ISBN 9780071778770.
  10. ^ Kent, Duncan (2011-02-04). The Insider's Guide to Choosing & Buying a Yacht: Expert Advice to Help You Choose the Perfect Yacht. Fernhurst Books Limited. ISBN 978-1-119-99918-8.
  11. ^ Slooff, J. W. (2015-04-25). The Aero- and Hydromechanics of Keel Yachts. Springer. p. 190. ISBN 9783319132754.

Bibliography edit

  • Rousmaniere, John, The Annapolis Book of Seamanship, Simon & Schuster, 1999
  • Chapman Book of Piloting (various contributors), Hearst Corporation, 1999
  • Herreshoff, Halsey (consulting editor), The Sailor's Handbook, Little Brown and Company
  • Seidman, David, The Complete Sailor, International Marine, 1995
  • Jobson, Gary, Sailing Fundamentals, Simon & Schuster, 1987

keel, other, uses, disambiguation, keel, bottom, most, longitudinal, structural, element, watercraft, some, sailboats, have, hydrodynamic, counterbalancing, purpose, well, laying, keel, often, initial, step, construction, ship, british, american, shipbuilding,. For other uses see Keel disambiguation The keel is the bottom most longitudinal structural element on a watercraft On some sailboats it may have a hydrodynamic and counterbalancing purpose as well The laying of the keel is often the initial step in the construction of a ship In the British and American shipbuilding traditions this event marks the beginning date of a ship s construction 1 Keel laid for the USS United States in drydock Contents 1 Etymology 2 History 2 1 Origins 2 2 Construction styles 2 2 1 Frame first 2 2 2 Plank first 3 Structural keels 4 Hydrodynamic keels 4 1 Sailboat keels 5 See also 6 Notes 7 BibliographyEtymology editThe word keel comes from Old English ceol Old Norse kjoll ship or keel It has the distinction of being regarded by some scholars as the first word in the English language recorded in writing having been recorded by Gildas in his 6th century Latin work De Excidio et Conquestu Britanniae under the spelling cyulae he was referring to the three ships that the Saxons first arrived in 2 3 Carina is the Latin word for keel and is the origin of the term careen to clean a keel and the hull in general often by rolling the ship on its side An example of this use is Careening Cove a suburb of Sydney Australia where careening was carried out in early colonial days History editOrigins edit nbsp Carvel built hull construction right lines planks up edge to edgeThe use of a keel in sailing vessels goes back to antiquity The wreck of an ancient Greek merchant ship known as the Kyrenia ship establishes the origin of the keel at least as far back as 315 BC 4 page needed The Uluburun shipwreck c 1325 BC had a rudimentary keel but it may have been more of a center plank than a keel 5 Construction styles edit Further information Boat building Frame first edit In carvel built hulls construction began with the laying of the keel followed by the stern and stem Frames were set up afterward set at key points along the keel Later the keelson was attached to the keel either bolted or with treenails 6 Plank first edit nbsp Look up planking in Wiktionary the free dictionary This section is empty You can help by adding to it Find sources plank first shipbuilding news newspapers books scholar JSTOR December 2023 Structural keels editA structural keel is the bottom most structural member around which the hull of a ship is built The keel runs along the centerline of the ship from the bow to the stern The keel is often the first part of a ship s hull to be constructed and laying the keel or placing the keel in the cradle in which the ship will be built may mark the start time of its construction Large modern ships are now often built in a series of pre fabricated complete hull sections rather than being built around a single keel so the shipbuilding process commences with the cutting of the first sheet of steel 7 The most common type of keel is the flat plate keel and this is fitted in the majority of ocean going ships and other vessels A form of keel found on smaller vessels is the bar keel which may be fitted in trawlers tugs and smaller ferries Where grounding is possible this type of keel is suitable with its massive scantlings but there is always a problem of the increased draft with no additional cargo capacity If a double bottom is fitted the keel is almost inevitably of the flat plate type bar keels often being associated with open floors where the plate keel may also be fitted citation needed Hydrodynamic keels editHydrodynamic keels have the primary purpose of interacting with the water and are typical of certain sailboats Fixed hydrodynamic keels have the structural strength to support the weight of the boat 8 nbsp Sailing yacht with a fin keel nbsp Lateral resistance effect of a sailing keel nbsp Righting effect of a keel where A is the center of buoyancy and G is the centre of gravity hypothetical example Sailboat keels edit In sailboats keels serve two purposes 1 as an underwater foil to minimize the lateral motion of the vessel under sail leeway and 2 as a counterweight to the lateral force of the wind on the sail s that causes rolling to the side heeling As an underwater foil a keel uses the forward motion of the boat to generate lift to counteract the leeward force of the wind Related foils include centerboards and daggerboards which do not have the secondary purpose of being a counterweight As counterweight a keel increasingly offsets the heeling moment with increasing angle of heel Moveable sailboat keels may pivot a swing keel 9 retract upwards retracting keel 10 or swing sideways in the water canting keels to move the ballasting effect to one side and allow the boat to sail in a more upright position 11 See also editCoin ceremony Kelson False keel Daggerboard Leeboard Bilgeboard Bruce foil Keelhauling an archaic maritime punishment Keel blockNotes edit Man Myth amp Magic The Illustrated Encyclopedia of Mythology Religion and the Unknown M Cavendish 1995 p 2364 ISBN 9781854357311 Gildas The Ruin of Britain amp c 1899 pp 4 252 The Ruin of Britain G W Whittaker 1970 Collected Essays Ayer Publishing p 44 ISBN 0 8369 1636 0 Katzev Susan Womer Swiny Helena Wylde 2022 The Kyrenia Ship Final Excavation Report Volume I History of the Excavation Amphoras Pottery and Coins as Evidence for Dating Oxbow Books ISBN 9781785707520 Pulak Cemal 1998 The Uluburun Shipwreck An Overview The International Journal of Nautical Archaeology 27 3 210 doi 10 1111 j 1095 9270 1998 tb00803 x Adams Jonathan R 2013 A Maritime Archaeology of Ships Innovation and Social Change in Late Medieval and Early Modern Europe A Maritime Archaeology of Early Modern Europe Oxford Oxbow Books ISBN 978 1 78297 047 7 OCLC 862401040 p 76 Walton Thomas 1901 Know Your Own Ship London Charles Griffin amp Company pp 57 60 ISBN 9783861951643 Streiffert Bo September 1994 Modern Boat Maintenance The Complete Fiberglass Boat Manual Sheridan House Inc p 173 ISBN 978 0 924486 71 5 Spurr Daniel 2004 07 02 Your First Sailboat How to Find and Sail the Right Boat for You McGraw Hill Professional p 10 ISBN 9780071778770 Kent Duncan 2011 02 04 The Insider s Guide to Choosing amp Buying a Yacht Expert Advice to Help You Choose the Perfect Yacht Fernhurst Books Limited ISBN 978 1 119 99918 8 Slooff J W 2015 04 25 The Aero and Hydromechanics of Keel Yachts Springer p 190 ISBN 9783319132754 Bibliography edit nbsp Wikimedia Commons has media related to Keels Rousmaniere John The Annapolis Book of Seamanship Simon amp Schuster 1999 Chapman Book of Piloting various contributors Hearst Corporation 1999 Herreshoff Halsey consulting editor The Sailor s Handbook Little Brown and Company Seidman David The Complete Sailor International Marine 1995 Jobson Gary Sailing Fundamentals Simon amp Schuster 1987 Retrieved from https en wikipedia org w index php title Keel amp oldid 1188246554, wikipedia, wiki, book, books, library,

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