词条 | Jibboom |
释义 |
A jibboom (also spelt jib-boom) is a spar used to extend the length of a bowsprit on sailing ships.{{sfn|Smyth|2008|p=412}} It can itself be extended further by a flying jib-boom.{{sfn|Smyth|2008|p=412}} The heel (i.e. rear and lower) end of the flying jib-boom is attached to the jib-boom, and the heel of the jib-boom to the bowsprit. The point (i.e. higher and fore end) of the flying jib-boom is generally the fore-most extent of a ship. The jib- and flying jib- booms carry the tacks of the jib and flying jib sails, respectively, and the stay for the fore topgallant mast and the royal stay. Jib-boomThe jib-boom is—as the name suggests—the boom for the jib, extending its foot.{{sfn|Smyth|2008|p=412}} On smaller, merchant, sailing ships, it is commonly attached to the bowsprit by a cap and a saddle, either lashed down or secured with a crupper chain.{{sfn|Smyth|2008|p=412}}{{sfn|Nares|1868|p=45}}{{sfn|Jamieson|1829|p=530}} Alternatively, it can be attached by a boom iron and a cap, or even by two boom irons.{{sfn|Jamieson|1829|p=530}} The cap and saddle allow it to be withdrawn aft along the bowsprit as a ship enters harbour, reducing the opportunity for passing ships to glance against it and snap it off from the bowsprit.{{sfn|Jamieson|1829|p=530}} It is octagonal in cross-section at its heel end.{{sfn|Boyd|1864|p=133}} If secured by a chain to the bowsprit, it is iron-scored at the heel.{{sfn|Boyd|1864|p=133}} At its point it is also (partly) octagonal in cross-section, the same as is the boom iron that secures the flying jib-boom to it.{{sfn|Boyd|1864|p=133}} The flying jib-boom lies against the upper starboard side of the octagon.{{sfn|Boyd|1864|p=133}} The stay of the fore topgallant mast is attached to the jib-boom at the extremity of its point.{{sfn|Smyth|2008|p=412}}{{sfn|Boyd|1864|p=133}}{{sfn|Moore|1801}} The stay for the jib sail is attached to the shouldering at its heel.{{sfn|Boyd|1864|p=133}} Just as the bowsprit has bobstays, in order to counteract the upward force from the jib and fore topgallant stays a martingale hangs down from the point of the jib-boom to a dolphin striker, pulling downwards on the jib-boom.{{sfn|Biddlecombe|1925|p=20}} Flying jib-boomThe flying jib-boom is secured, at its heel end, to the jib-boom by a boom iron and lashing.{{sfn|Smyth|2008|p=412}} At its point, it has a sheave for the royal stay.{{sfn|Boyd|1864|p=133}}{{sfn|Moore|1801}} Another sheave at the heel is for a heel rope.{{sfn|Boyd|1864|p=133}} It is to the point that the tack of the flying jib sail is drawn out.{{sfn|Jamieson|1829|p=530}} ReferencesCross-referenceSources used{{refbegin}}
Dover Maritime Series|first=George|last=Biddlecombe|edition=reprinted 1990 by Courier Dover Publications|location=Salem, Massachusetts|publisher=The Marine Research Society|isbn=978-0-486-26343-4|article=Martingale|year=1925}}
Further reading
1 : Sailing rigs and rigging |
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