Definition of helm in English

WordNet

Noun Plural: helms
helm - steering mechanism for a vessel; a mechanical device by which a vessel is steered
		steering mechanism, steering system a mechanism by which something is steered (especially a motor vehicle)
		motorboat, powerboat a boat propelled by an internal-combustion engine
		sailing ship, sailing vessel a vessel that is powered by the wind; often having several masts
		ship a vessel that carries passengers or freight
		towboat, tugboat, tug, tower a powerful small boat designed to pull or push larger ships
helm - a position of leadership; "the President is at the helm of the Ship of State"
Verb helms, helming, helmed
helm - be at or take the helm of; "helm the ship"
		steer, manoeuvre, manoeuver, maneuver, channelize, channelise, guide, head, direct, point direct the course; determine the direction of travelling

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Wiktionary

helm (Noun)
The steering apparatus of a ship, especially the tiller or wheel.
helm (Noun)
The member of the crew in charge of steering the boat.
helm (Noun)
A position of leadership or control.
helm (Noun)
A helmet.
helm (Noun)
A heavy cloud lying on the brow of a mountain.
helm (Verb)
To be a helmsman or a member of the helm; to be in charge of steering the boat.
helm (Verb)
To lead a project, etc..

Webster DictionaryWebster's Unabridged Dictionary 📘

helm (n.)
See Haulm, straw.
helm (n.)
The apparatus by which a ship is steered, comprising rudder, tiller, wheel, etc.; -- commonly used of the tiller or wheel alone.
helm (n.)
The place or office of direction or administration.
helm (n.)
One at the place of direction or control; a steersman; hence, a guide; a director.
helm (n.)
A helve.
helm (v. t.)
To steer; to guide; to direct.
helm (n.)
A helmet.
helm (n.)
A heavy cloud lying on the brow of a mountain.
helm (v. t.)
To cover or furnish with a helm or helmet.

Chambers DictionaryChamber's 20th Century Dictionary 📕

helm
helm, n. the instrument by which a ship is steered: the station of management or government.—v.t. to direct.—n. Helm′age, guidance.—adj. Helm′less, of a ship, without a helm.—n. Helms′man, the one who steers. [A.S. helma; Ice. hjálm, a rudder, Gr. helm, a handle.]
helm
helm, Helmet, hel′met, n. a covering of armour for the head: (bot.) the hooded upper lip of certain flowers.—adjs. Helmed, Hel′meted, furnished with a helmet.—n. Hel′met-shell, a genus of gasteropods having thick heavy shells with bold ridges: a cameo-shell. [A.S. helm—helan, to cover; Ger. helm.]

Marine DictionaryUniversal Dictionary of the Marine ⚓️

helm
gouvernail, (helme, Sax.) a long and flat piece of 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.
The length and breadth of the rudder are represented in plate VIII. where it is evident that it becomes gradually broader in proportion 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. The hinges upon which it is supported are also expressed in this figure. Those which are bolted round the stern-post to the after extremity of the ship, are called googings, and are furnished with a large hole on the afterpart of the stern-post. The other parts of the hinges, which are bolted to the back of the rudder, are called pintles, being strong cylindrical pins, which enter into the googings, and rest upon them. The length and thickness of the rudder is nearly equal to that of the stern-post, as represented in fig. 1. plate X.
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, accordingly, direct the efforts of the rudder to the government of the ship’s course as she advances, which, in the sea-language, 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 usually composed of untarred rope-yarns, for the purpose of traversing more readily through the blocks or pullies.
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. The rope employed in this service being conveyed from the fore-end of the tiller k, to a single block i, on each side of the ship, (plate III. DECK) is farther communicated to the wheel, by means of two blocks, suspended near the mizen-mast, and two holes immediately above, leading up to the wheel, which is fixed upon an axis, on the quarter-deck, almost perpendicularly over the fore end of the tiller. Five turns of the tiller-rope are usually wound about the barrel of the wheel, and, when the helm is amidship, the middle turn is nailed to the top of the barrel, with a mark by which the helmsman readily discovers the situation of the helm, as the wheel turns it from the starboard to the larboard side. The spokes of the wheel generally reach about eight inches beyond the rim or circumference, serving as handles to the person who steers the vessel. As the effect of a lever increases in proportion to the length of its arm, it is evident that the power of the helmsman, to turn the wheel, will be increased according to the length of the spokes, beyond the circumference of the barrel.
When the helm, instead of lying in a right line with the keel, is turned to one side or the other, as in BD, fig. 1. plate V. it receives an immediate shock from the water, which glides along the ship’s bottom in running aft from A to B; and this fluid pushes it towards the opposite side, whilst it is retained in this position: so that the stern, to which the rudder is confined, receives the same impression, and accordingly turns from B to b about some point c whilst the head of the ship passes from A to a. It must be observed, that the current of water falls upon the rudder obliquely, and only strikes it with that part of its motion which acts according to the sine of incidence, pushing it in the direction N P, with a force which not only depends on the velocity of the ship’s course, by which this current of water is produced, but also upon the extent of the sine of incidence. This force is by consequence composed of the square of the velocity with which the ship advances, and the square of the sine of incidence, which will necessarily be greater or smaller according to circumstances; so that if the vessel runs three or four times more swiftly, the absolute shock of the water upon the rudder will be nine or sixteen times stronger under the same incidence: and, if the incidence is increased, it will yet be augmented in a greater proportion, because the square of the sine of incidence is more enlarged. This impression, or, what is the same thing, the power of the helm, is always very feeble, when compared with the weight of the vessel; but as it operates with the force of a long lever, its efforts to turn the ship are extremely advantageous. For the helm being applied to a great distance from the centre of gravity, G, or from the point about which the vessel turns horizontally, if the direction P N of the impression of the water upon the rudder be prolonged, it is evident that it will pass perpendicularly to R, widely distant from the centre of gravity G: thus the absolute effort of the water is very powerful. It is not therefore surprizing that this machine impresses the ship with a considerable circular movement, by pushing the stern from B to b, and the head from A to a; and even much farther, whilst the sails with rapidity: because the effect of the helm always keeps pace with the velocity with which the vessel advances[31].
Amongst the several angles that the rudder makes with the keel, there is always one position more favourable than any of the others, as it more readily produces the desired effect of turning the ship, in order to change her course. To ascertain this, it must be considered, that if the obliquity of the rudder with the keel is greater than the obtuse angle A B D, so as to diminish that angle, the action of the water upon the rudder will increase, and at the same time oppose the course of the ship in a greater degree; because the angle of incidence will be more open, so as to present a greater surface to the shock of the water, by opposing its passage more perpendicularly. But at that time the direction N P of the effort of the helm upon the ship will pass, with a smaller distance from the centre of gravity G towards R, and less approach the perpendicular N L, according to which it is absolutely necessary that the power applied should act with a greater effect to turn the vessel. Thus it is evident that if the obtuse angle A B D is too much enclosed, the greatest impulse of the water will not counterbalance the loss sustained by the distance of the direction N P from N L; or by the great obliquity, which is given to the same direction N P of the absolute effort of the helm with the keel A B. If, on the contrary, the angle A B D is too much opened, the direction N P of the force of action of the helm will become more advantageous to turn the vessel, because it will approach nearer the perpendicular N L; so that the line prolonged from N P will increase the line G R, by removing R to a greater distance from the centre of gravity G: but then the helm will receive the impression of the water too obliquely, for the angle of incidence will be more acute; so that it will only present a small portion of its breadth to the shock of the water, and by consequence will only receive a feeble effort. By this principle it is easy to conceive, that the greatest distance G R from the centre of gravity G is not sufficient to repair the diminution of force occasioned by the too great obliquity of the shock of the water. Hence we may conclude, that when the water either strikes the helm too directly, or too obliquely, it loses a great deal of the effect it ought to produce. Between the two extremes there is therefore a mean position, which is the most favourable to its operations.
The diagonal N P of the rectangle I L represents the absolute direction of the effort of the water upon the helm. N I expresses the portion of this effort which is opposed to the ship’s head-way, or which pushes her astern, in a direction parallel to the keel. It is easily perceived that this part N I of the whole power of the helm contributes but little to turn the vessel; for if I N is prolonged, it appears that its direction approaches to a very small distance G V from the centre of gravity G, and that the arm of the lever B N=G V, to which the force is applied, is not in the whole more than equal to half the breadth of the rudder: but the relative force N L, which acts perpendicular to the keel, is extremely different. If the first N I is almost useless, and even pernicious, by retarding the velocity; the second N L is capable of a very great effect, because it operates at a considerable distance from the centre of gravity G of the ship, and acts upon the arm of a lever G E, which is very long. Thus it appears, that between the effects N L and N I, which result from the absolute effort N P, there is one which always opposes the ship’s course, and contributes little to her motion of turning; whilst the other produces only this movement of rotation, without operating to retard her velocity[32].
Geometricians have determined the most advantageous angle made by the helm with the line prolonged from the keel, and fixed it at 54° 44´ presuming that the ship is as narrow at her floating-line, or at the line described by the surface of the water round her bottom, as at the keel. But as this supposition is absolutely false, inasmuch as all vessels augment their breadth from the keel upward to the extreme breadth, where the floating-line or the highest water-line is terminated; it follows that this angle is too large by a certain number of degrees. For the rudder is impressed by the water, at the height of the floating-line, more directly than at the keel, because the fluid exactly follows the horizontal outlines of the bottom; so that a particular position of the helm might be supposed necessary for each different incidence which it encounters from the keel upwards. But as a middle position may be taken between all these points, it will be sufficient to consider the angle formed by the sides of the ship, and her axis, or the middle-line of her length, at the surface of the water, in order to determine afterwards the mean point, and the mean angle of incidence.
It is evident that the angle 54° 44´ is too open, and very unfavourable to the ship’s head-way, because the water acts upon the rudder there with too great a sine of incidence, as being equal to that of the angle which it makes with the line prolonged from the keel below: but above, the shock of the water is almost perpendicular to the rudder, because of the breadth of the bottom, as we have already remarked. If then the rudder is only opposed to the fluid, by making an angle of 45° with the line prolonged from the keel, the impression, by becoming weaker, will be less opposed to the ship’s head-way, and the direction N P, fig. 1. plate V. of the absolute effort of the water upon the helm drawing nearer to the lateral perpendicular, will be placed more advantageously, for the reasons above mentioned[33]. On the other hand, experience daily testifies, that a ship steers well when the rudder makes the angle D B E equal to 35° only.
It has been already remarked, that the effect of moving the wheel to govern the helm increases in proportion to the length of the spokes; and so great is the power of the wheel, that if the helmsman employs a force upon its spokes equivalent to 30 pounds, it will produce an effect of 90 or 120 pounds upon the tiller. On the contrary, the action of the water is collected into the middle of the breadth of the rudder, which is very narrow in companion with the length of the tiller; so the effort of the water is very little removed from the fulcrum B upon which it turns; whereas the tiller forms the arm of a lever ten or fifteen times longer, which also increases the power of the helmsman in the same proportion that the tiller bears to the lever upon which the impulse of the water is directed. This force then is by consequence ten or fifteen times stronger, and the effort of 30 pounds, which at first gave the helmsman a power equal to 90 or 120 pounds, becomes accumulated to one of 900 or 1800 pounds upon the rudder. This advantage then arises from the shortness of the lever upon which the action of the water is impressed, and the great comparative length of the tiller, or lever, by which the rudder is governed; together with the additional power of the wheel that directs the movements of the tiller, and still farther accumulates the power of the helmsman over it. Such a demonstration ought to remove the surprize with which the prodigious effect of the helm is sometimes considered, from an inattention to its mechanism: for we need only to observe the pressure of the water, which acts at a great distance from the centre of gravity G, about which the ship is supposed to turn, and we shall easily perceive the difference there is between the effort of the water against the helmsman, and the effect of the same impulse against the vessel. With regard to the person who steers, the water acts only with the arm of a very short lever N B, of which B is the fulcrum: on the contrary, with regard to the ship, the force of the water is impressed in the direction N P, which passes to a great distance from G, and acts upon a very long lever E G, which renders the action of the rudder extremely powerful in turning the vessel; so that, in a large ship, the rudder receives a shock from the water of 2700 or 2800 pounds, which is frequently the case, when she sails at the rate of three or four leagues by the hour; and this force being applied in E, perhaps 100 or 110 feet distant from the centre of gravity G, will operate upon the ship, to turn her about, with 270000 or 308000 pounds; whilst, in the latter case, the helmsman acts with an effort which exceeds not 30 pounds upon the spokes of the wheel.
After what has been said of the helm, it is easy to judge, that the more a ship increases her velocity with regard to the sea, the more powerful will be the effect of the rudder, because it acts against the water with a force, which increases as the square of the swiftness of the fluid, whether the ship advances or retreats; or, in other words, whether she has head-way or stern-way; with this distinction, that in these two circumstances the effects will be contrary. For if the vessel retreats, or moves astern, the helm will be impressed from I to N, fig. 1. plate V. and, instead of being pushed, according to N P, it will receive the effort of the water from N towards R; so that the stern wall be transported according to the same movement, and the head turned in a contrary direction.
When the helm operates by itself, the centre of rotation of the ship, and her movement, are determined by estimating the force of this machine; that is to say, by multiplying the surface of the rudder by the square of the ship’s velocity[34]. See the articles RUDDER, SAILING, STEERING, TRIM, and WORKING.

Sailor's Word-BookThe Sailor's Word-Book ⛵

helm
Properly is the tiller, but sometimes used to express the rudder, and the means used for turning it, which, in small vessels and boats, is merely a tiller, but in larger vessels a wheel is added, which supplies the leverage for pulling the tiller either way; they are connected by ropes or chains.--A-lee the helm, or Down with the helm! So place the tiller that the rudder is brought on the weather side of the stern-post. These, and the following orders, were established when tillers extended forward from the rudder-head, but now they often extend aft, which requires the motion of the tiller to be reversed. With the latter style of tiller the order "down with the helm" is carried out by bringing the tiller up to the weather side of the ship; which being done, the order "Helm's a lee" follows.--Bear up the helm. That is, let the ship go more large before the wind.--Ease the helm. To let the helm come more amidships, when it has been put hard up or down.--It is common to ease the helm before a heavy sea takes the ship when close-hauled.--Helm amidships, or right the helm. That is, keep it even with the middle of the ship, in a line with the keel.--Helm over. The position of the tiller to enable a vessel steaming ahead to describe a curve.--Port the helm. Place the tiller so as to carry the rudder to starboard. (See A-lee the helm.)--Shift the helm. Put it from port to starboard, and vice versâ, or it may be amidships.--Starboard the helm. Place the tiller so as to carry the rudder to port.--Up with the helm. Place the tiller so as to carry the rudder to leeward. (See A-lee the helm.)