The jib-boom is—as the name suggests—the
boom for the jib, extending its foot. 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. Alternatively, it can be attached by a
boom iron and a cap, or even by two boom irons. The cap and saddle allow it to be withdrawn aft along the bowsprit as a ship enters harbour, reducing the opportunity for passing ships to glance against it and snap it off from the bowsprit. It is octagonal in cross-section at its heel end. If secured by a chain to the bowsprit, it is iron-scored at the heel. 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. The flying jib-boom lies against the upper starboard side of the octagon. The stay of the fore topgallant mast is attached to the jib-boom at the extremity of its point. The stay for the jib sail is attached to the shouldering at its heel. 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. == Flying jib-boom ==