Flat-iron gunboat

Flat-iron gunboats (more formally known as Rendel gunboats) were a number of classes of coastal gunboats generally characterised by small size, low freeboard, the absence of masts, and the mounting of a single non-traversing large gun, aimed by pointing the vessel. They acquired their nickname from the physical similarity with the flat iron used for ironing clothes during the 19th century.

The first flat-iron gunboat was launched in 1867, and the last in 1894, with the vast majority being built in the years 1870 - 1880. They were designed as a cheap coastal defence weapon, a role they failed to achieve successfully; they found their greatest utility in offensive coastal bombardment. Strongly built, they lasted in some cases into the late 20th century, and saw action in both World Wars. The hull of the British flat-iron Medway lies in shallow water off Bermuda. The Norwegian flat-iron Tyr remains in service under the name Bjorn West, at last report entering Eidsvik shipyard in May 2014 for restoration.