A diagram of the three spars and some of the rigging that can make up a bow: A.) Bowsprit, B.) Jibboom, C.) Flying jib-boom, D.) Jibstay. E.) Fore Topgallant Stay, F.) Flying Jibstay, G.) Fore Royal Stay, H.) Topmast stays, I.) Outer Forestay, J.) Inner Forestay

A jibboom (also spelled jib-boom) is a spar used to extend the length of a bowsprit on sailing ships.[1] It can itself be extended further by a flying jib-boom.[1] 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.

In yachts it is a boom attached to the foot of the jib, to keep the shape of the sail in different wind angles and to allow self tacking.


The jib-boom is—as the name suggests—the boom for the jib, extending its foot.[1] 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.[1][2][3] Alternatively, it can be attached by a boom iron and a cap, or even by two boom irons.[3] The cap and saddle allow it to be withdrawn aft along the bowsprit as a ship enters harbour, reducing the opportunity for passing ships to glance against it and snap it off from the bowsprit.[3]

It is octagonal in cross-section at its heel end.[4] If secured by a chain to the bowsprit, it is iron-scored at the heel.[4] 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.[4] The flying jib-boom lies against the upper starboard side of the octagon.[4]

The stay of the fore topgallant mast is attached to the jib-boom at the extremity of its point.[1][4][5] The stay for the jib sail is attached to the shouldering at its heel.[4] 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.[6]

Flying jib-boom

The flying jib-boom is secured, at its heel end, to the jib-boom by a boom iron and lashing.[1] At its point, it has a sheave for the royal stay.[4][5] Another sheave at the heel is for a heel rope.[4] It is to the point that the tack of the flying jib sail is drawn out.[3]



  1. ^ a b c d e f Smyth 2008, p. 412.
  2. ^ Nares 1868, p. 45.
  3. ^ a b c d Jamieson 1829, p. 530.
  4. ^ a b c d e f g h Boyd 1857, p. 133.
  5. ^ a b Moore 1801.
  6. ^ Biddlecombe 1925, p. 20.

Sources used

Further reading