A ship's wheel or boat's wheel is a device used aboard a

ship A ship is a large watercraft, vessel that travels the world's oceans and other Waterway, navigable waterways, carrying cargo or passengers, or in support of specialized missions, such as defense, research and fishing. Ships are generally disti ...

boat A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size or capacity, its shape, or its ability to carry boats. Small boats are typically used on inland waterways s ...

submarine A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...

, or

airship An airship, dirigible balloon or dirigible is a type of aerostat (lighter-than-air) aircraft that can navigate through the air flying powered aircraft, under its own power. Aerostats use buoyancy from a lifting gas that is less dense than the ...

, with which a helmsman steers the vessel and controls its course. Together with the rest of the steering mechanism, it forms part of the helm (the term ''helm'' can mean the wheel alone, or the entire mechanism by which the rudder is controlled). It is connected to a mechanical, electric servo, or hydraulic system which alters the horizontal angle of the vessel's rudder relative to its hull. In some modern ships the wheel is replaced with a simple toggle that remotely controls an electro-mechanical or electro-hydraulic drive for the rudder, with a rudder position indicator presenting feedback to the helmsman.

History

Until the invention of the ship's wheel, the helmsman relied on a tiller—a horizontal bar fitted directly to the top of the rudder post—or a whipstaff—a vertical stick acting on the arm of the ship's tiller. Near the start of the 18th century, a large number of vessels appeared using the ship's wheel design, but historians are unclear when the approach was first used.

Design

A ship's wheel is composed of eight cylindrical wooden spokes (though sometimes as few as six or as many as ten or twelve depending on the wheel's size and how much force is needed to turn it.) shaped like balusters and all joined at a central wooden hub or ''nave'' (sometimes covered with a brass ''nave plate'') which houses the axle. The square hole at the centre of the hub through which the axle runs is called the ''drive square'' and was often lined with a brass plate (and therefore called a ''brass boss'', though this term was used more often to refer to a brass hub and nave plate) which was frequently etched with the name of the wheel's manufacturer. The outer rim is composed of sections each made up of stacks of three ''felloes'', the ''facing felloe'', the ''middle felloe'', and the ''after felloe''. Because each group of three felloes at one time made up a quarter of the distance around the rim, the entire outer wooden wheel was sometimes called the ''quadrant''. Each spoke runs through the middle felloe, creating a series of handles beyond the wheel's rim. One of these handles/spokes was frequently provided with extra grooves at its tip which could be felt by a helmsman steering in the dark and used by him to determine the exact position of the rudder—this is the ''king spoke'', and when it pointed straight upward the rudder was believed to be dead straight to the hull. The completed ship's wheel and associated axle and pedestals might even be taller than the person using it. The wood used in construction of this type of wheel was most often either teak or mahogany, both of which are very durable tropical

hardwood Hardwood is wood from Flowering plant, angiosperm trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal ecosystem, boreal latitudes they are mostly deciduous, but in tropics and subtropics mostl ...

s capable of surviving the effects of salt water spray and regular use without significant decomposition. Modern design—particularly on smaller vessels—can deviate from the template.

Mechanism

The steering gear of earlier ships' wheels sometimes consisted of a double wheel where each wheel was connected to the other with a wooden ''spindle'' that ran through a ''barrel'' or ''drum''. The spindle was held up by two ''pedestals'' that rested on a wooden ''platform'', often no more than a grate. A ''tiller rope'' or ''tiller chain'' (sometimes called a ''steering rope'' or ''steering chain'') ran around the barrel in five or six loops and then down through two ''tiller rope/ chain slots'' at the top of the platform before connecting to two sheaves just below deck (one on either side of the ship's wheel) and thence out to a pair of pulleys before coming back together at the tiller and connecting to the ship's rudder. Movement of the wheels (which were connected and moved in unison) caused the tiller rope to wind in one of two directions and angled the tiller left or right. In a typical and intuitive arrangement, a forward-facing helmsman turning the wheel ''counter''clockwise would cause the tiller to angle to starboard and therefore the rudder to swing to port causing the vessel to also turn to port (see animation). Having two wheels connected by an axle allowed two people to take the helm in severe weather when one person alone might not have had enough strength to control the ship's movements. When at the full extent of travel, the wheel and rudder are said to be "hard over", hence the order "hard

port A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Hamburg, Manch ...

/ starboard" given by Captain/ Officer of the Watch.

Gallery

File:Britannia Yacht Club Commodore Boardroom.jpg, Britannia Yacht Club's Commodore Boardroom features a ship's wheel table File:Annunciator.jpg, USS ''LST-325'' ship's wheel and engine order telegraph, the latter also referred to in the

US Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

as the lee helm File:US Navy 050823-N-9076B-001 Electrician's Mate 1st Class Aaron Walker speaks to chief petty officer selectees as he stands at the helm of USS Constitution in Boston.jpg, U.S. Navy personnel aboard , by the ship's wheel File:Kitee.vaakuna.svg, Ship's wheel pictured in the coat of arms of Kitee

References

External links