HELM, in naval architecture, a lone and flat piecenf timber, or an assemblage of several pieces, suspended along the hind part of a ship's stern.post, where it turns upon hinges to the right or left, serving to direct the course of the vessel, as the tail of a fish guides the body. The helm is usually composed of three parts, viz. the rudder, the tiller, and the wheel, except in small vessels, where the wheel is unnecessary. As to the form of the rud der it becomes gradually broader in pro portion to its distance from the top, or to its depth under the water. The back, or inner part of it, which joins to the stern post, is diminished into the form of a wedge throughout its whole length, so as that the rudder may be more easily turned from one side to the other, where it makes an obtuse angle with the keel. It is supported upon hinges, of which those that are bolted round the stern. post to the after extremity of the ship are called googings, and are furnished with a large hole in the after-part of the stern 'post. The other parts of the binges, which are bolted to the back of the rud der, are called pintles, being strong cy lindrical pins, which enter into the goog ings and rest upon them. The length and thickness of the rudder is nearly equal to that of the stern-post. The rudder
is turned upon its hinges by means of a long bar of timber called the tiller, which is •fixed horizontally in its upper end within the vessel. The movements of the tiller, to the right and left, according ingly direct the efforts of the rudder to the government of the ship's course as she advances; which, in the sealanguage, is called steering. The operations of the tiller are guided and assisted by a sort of tackle, communicating with the ship's side, called the tiller-rope, which is usu ally composed of untarred rope-yarns, for the rurnose f t'aversing more readily through the blocks or pulleys. In order to facilitate the management of the helm, the tiller-rope, in all large vessels, is wound about a wheel, which acts upon it with the powers of a crane or windlass.
There are several terms in the sea lan guage relating to the helm ; as " bear up the helm ;" that is, let the ship go more large before the wind : " helm a mid ship," or "right the helm ;" that is, keep it even with the middle of the ship ; " port the helm," put it over the left side of the ship : " starboard the helm," put it on the right side of the ship.