Hedderwick: Marine Architecture (1830)


Steering Apparatus. — First, the Tiller. — This is a lever of wood or iron, as found most convenient; it is fixed at one end into the head of the rudder, and at the other end the power is applied for steering the vessel. Its length from the rudder-head should be about four times the breadth of the rudder; its thickness at the fore part of the mortise, the twartship way, about 5-11ths, or one half the siding dimension of the rudder-head, and its depth at the same place one a half times its breadth. In lining out this piece, it is generally kept about 3-4ths of an inch broader than the mortise the thwartship way at the rudder-head, and tapered from that to the end or tiller-head, to 1-3d of the breadth and depth added together. Thus suppose the breadth 5 inches, and depth 7 inches; then the 5 + 7 = 12, and 1-3d of 12 is 4 inches for the diameter of the head. The length of the tiller from the rudder-head to the end is divided into three equal parts; that next the rudder is left dquare; the middle division has the corners taken off in form of an octagon, and from that to the head is made round. The head is left about half an inch thicker, and paned up like a diamond, or carved to fancy.

It is found by experience, that a good steering vessel of 200 tons, having a rudder of 3 feet broad, and tiller of 12 feet (making a power of 4 to 1 with the extremity of the rudder), may be steered by one man without the assistance of any other power, when the weather is moderate. However, in strong winds the power must be increased. In vessels which have not a steering wheel, this is frequently done by fixing a block to the end of the tiller, and another to at the rail or side of the ship; a rope is then rove through these blocks, one end being made fast at the rail, and the other held in the hands of the man steering; the power is thus doubled, being 8 to 1.

Various methods of increasing the power for steering are adopted. Most vessels under 300 tons are steered with the tiller and tiller-ropes, as above mentioned. Larger vessels are commonly steered by a power produced with the wheel and axle. The wheel is called the Steering Wheel. It is erected on the deck a little before the tiller. It is also sometimes fitted abaft the rudder-head, or where found most convenient. The wheel is made similar to any common coach-wheel, only having the addition of hand-knobs or spokes on the outside of the rim, to lay hold of by the hands in turning it round. The wheel stands vertically, being fixed on a horizontal iron spindle (it must be copper, if near the compass), on which is also fixed a drum or barrel. The wheels vary in dimensions from 3½ to 5 feet in diameter over the extremity of the hand-knobs; the drum or barrel on which the tiller ropes are wound, is from 1-5th to 1-4th the extreme diameter of the wheel. The wheel-ropes are made fast to the end of the tiller, and pass through sheves [sic] or blocks fixed to the side rail of the vessel opposite the tiller-head, then to the barrel of the wheel, so that by turning the wheel either way, the tiller will move accordingly.

In the case of the tiller being of the common length, i.e. as long as to produce a power of three to one with the breadth of the rudder, the wheel rope is brought immediately from the tiller to the barrel of the vessel, having only the sheves or blocks at the rail to conduct the rope fair to the barrel. Suppose the breadth of the rudder of a ship of 300 tons to be 3½ feet, the length of the tiller 11 feet, making, by the tiller alone, a power of 3 to 1; that the tiller-rope is taken to the barrel of a wheel whose power is 4 to 1; then a power of 4 to 1, acting upon a power of 3 to 1, produces a total power of 12 to 1, as compared with the extreme breadth of the rudder; and with this, one man will be able to steer any common vessel of about this size. But for ships of 400 or 500 tons, the power must be made equal to about 18 or 20 to 1, to be steered in the same manner, with the common tiller and wheel, by one man only.

When the vessel is to be steered with a tiller abaft the rudder-head, which in this case must be very short (in many vessels it cannot be allowed longer than the breadth of the rudder), a great increase of power of the wheel, or by tackles from each side to the tiller and wheel, either by the one or other of these, or by both, is required. It is most frequently done by fixing a purchase of 2 or 3 to 1 on the end of the short tiller, and reducing the diameter of the barrel, to give the wheel more power over the barrel.

There are many other methods which might be employed for augmenting the power, as by wheels and pinions, &c. Whatever method may be employed, the power must always be adequate to steer the vessel by one or two men.

The wheel is considered to be of great advantage, not only in giving more power, but also in enabling the helmsman to steer the vessel nearer her true course. Mostly all vessels are fitted with steering wheels, even some of our one-masted vessels, such as smacks, have them, although it is considered to be a little more in the way of the main-sheet than the common tiller.

Peter Hedderwick: A Treatise on Marine Architecture, containing the theory and practice of shipbuilding, with rules for the proportions of masts, rigging, weight of anchors, &c including Practical Geometry and the Principles of Mechanics; observations on the Strength of Materials, Hydrostatics, &c. with many valuable tables calculated for the use of shipwrights and seamen; also the proportions, scantlings, construction, and propelling power of steam-ships. Illustrated with twenty large plates, containing plans and draughts of merchant-vessels from fifty to five hundred tons, with mast and rigging plans; plans and sections of a steam-boat of eighty-horse power; and eight quarto plates of diagrams, &c., by Peter Hedderwick.
Printed for the Author, Edinburgh, 1830. pp 323-324.

Transcribed by Lars Bruzelius

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