WHAT we call the helm is the tiller, that turns the rudder on either side, of the after part of the keel and stern-post, for the water to act upon, as the management of the ship may require; and as ships differ in breadth abaft, so should the tiller in its length; that is, the tiller should be just long enough to reach close over to each side, when the rudder stands at an angle of 33 degrees or bears three points of the compass from the direction of the keel, which is generally allowed to answer best; for to make the rudder go over, is found from experience to increase the resistance of the ship's way, which lessens the power of the rudder, to steer and manage the ship, in proportion as she loses her way through the water. Fault of the helm going too much over. Yet in boats and larger vessels, where the rudder and tiller admit of it, I have seen people so stupid, as to put the helm in tacking almost right athwart the stern, which tends more to stop the vessels way, than to bring her head round against the wind and waves, from one tack to the other. This shews how necessary it is as far as possible, to have things fixed by the best rules, to prevent such bad practice.
To confirm that the angle of 33 degrees is sufficient, with a bevil I tried the rudders of many ships, some built sharp for sailing, others full for carrying, Dutch as well as English, and found some, tho' very few of their rudders, that stood at so large an angle as 33 degrees, Fault of the helm not going enough over. but most at about 30 degrees, and several at but about 28 degrees or two points and a half, which is certainly a fault, to loose any of the rudders outmost power, because it is often wanted on the most important occasions, when safety may depend upon it.
Moving the helm can have no effect to manage a ship but when she passes through the water, or the water passes by her, in a tide or currents way, then the water gives equal power to the helm, as if the ship went at that rate through the water.
When the helm is a midships, the rudder can have no effect to turn the ship either way, as it then stands in the same direction with the keel and sternpost; The effect of the water upon the rudder. but suppose the helm put to starboard, it turns the rudder towards the larboard side of the ship, which makes the larboard side of the rudder to resist the water, which acts with a power according to its velocity, or the ship's head way thro' the water, against the larboard side of the rudder, to turn the ship's stern to starboard, and consequently her head to port, and the center of this turning motion, is allow'd to be at the ships center of gravity, as mentioned page the 14th. It may easily be perceived that when the helm is put hard a port, how it acts, from the same causes to turn the ships head to starboard, as may be seen by looking at plate the 7th, where the plane of a ship, in three different situations is represented with the helm hard a-port, which makes it evident that when the ship has headway, the water must act against the starboard side of the rudder, in a direction so as to turn the ships stern to port, or towards that side the helm or tiller is put upon, and her head to starboard from that side that the helm lies, as abovementioned.
William Hutchinson: A Treatise on Practical Seamanship; with
Hints and Remarks Relating Thereto: Designed to Contribute
Something towards Fixing Rules upon Philosophical and Rational
Principles; to Make Ships, and the Management of Them; and
also Navigation, in General, more Perfect, and Consequently
less Dangerous and Destructive to Health, Lives, and Property.
Printed for the Author, Liverpool, 1777. pp 38-39.
Transcribed by Lars Bruzelius
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