IMPROVEMENTS IN STEERING APPARATUS FOR SHIPS TO PRODUCE AN EVEN TENSION IN THE ROPE OR CHAIN AT ALL POSITIONS OF THE HELM TO AVOID SLACK
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by William Morgan-Brown at the Office
of the Commissioners of Patents on the 16th May 1881. A communication
from abroad by Heinrich Lindemann, of Wilhelmshafen, Germany.
WILLIAM MORGAN-BROWN, Patent Agent, of 38, Southampton Buildings,
London. "IMPROVEMENTS IN STEERING APPARATUS FOR SHIPS TO PRODUCE AN
EVEN TENSION IN THE ROPE OR CHAIN AT ALL POSITIONS OF THE HELM TO
AVOID SLACK." [A communication from abroad by Heinrich Lindemann, of
Wilhelmshafen, Germany.]
The arrangement of a tiller carrying at its end a pair of fixed blocks or blocks
turning upon a pivot or bolt, and having the standing parts attached to the vessel's
sides, has the great inconvenience that the standing parts in putting the helm
aport or to starboard become loose, their bight increasing with the angle under
which the helm is placed.
From the skeleton plan, Figure 1ª, Sheet I. (in which the line IC represents the
position of tiller amidships, and IC', IC positions under angles a' and a²), it will
be seen that the sides AC + C B of triangle A C¹B are smaller than the sides
AC + CB of triangle ACB, and that the sides A C" + C" B of triangle A C" B
are smaller than the sides of AC + CB of triangle AC B, etc., the decrease always
growing with the increase of the angles a¹, a², etc., and this explains the "slack" in
the standing parts.
According to this new arrangement, I attach the standing parts, instead of
fastening them to the sides, to the rudder head, or before or behind it, at a convenient
point in the middle line IC (Sheet I.)
Then I put the rudder over to starboard or to port, say, for any angle a¹, and I
straighten the excess of rope into its original tension by pressing the bight in an
angle, the vertex of which comes into the middle line I Č. Thus a point M will be
found in the middle line, and the standing parts fixed at this point will avoid slack
for the position of the helm under angle a'. In the same way similar points
M, M, etc., can be found in the middle line to avoid slack in the standing parts for
the position of the helm under angles a¹, a², etc.
If these points were falling together, the slack might be easily dispensed with
for all positions of the helm, by attaching the standing parts at this point (see
Sheet I., Figures 1 and 2, upper and side view of the steering apparatus).

page_text: This is however not so, and these points approach more and more to C with the
increase of the angle under which the tiller is placed.
The practical employment of the above explanations can be effected by putting
the helm close on board. Then the point M will be determined for this position of
the helm in the above described manner, and at this point a bolt with a turning
ring will be applied for fastening the standing parts of the rope (see Figures 1 and 2,
Sheet I.)
This will be sufficient for smaller ships with short tiller, or with rudder angles
not larger than 35-38°, but to avoid completely the slack in a steering apparatus
for larger ships with a rudder angle up to 41 or 42°, I make use of a second
arrangement (Sheet II). Having prepared the blocks and the standing parts in
the above described manner, and the rope has an even tension while the helm is
amidships (rudder angle=0), the helm is moved from amidships to a position of
10°, then the bight of the standing parts will be hauled tight to the middle line I C
(Figure 1ª, Sheet I.), till the rope has regained its former tension, hereafter a spun
yarn, better an iron wire of about 1/ thickness is fastened over the tiller in
the deck parallel to the standing parts.
This operation will be repeated for all positions of the tiller under 20-30-35°,
and finally under the maximum rudder angle. The wires form thus a curved line,
and a piece S, formed according to this curved line, will be made and fastened to
the deck in the middle line. When now the standing parts of the rope or chain
are guided through the eye in the piece S, the slack in the rope will be avoided for
all positions of the helm."
Instead of using the fixed pieces S, S, two sheaves S¹, S¹, turning on bolts (sheaves
of the ordinary size as those in the pin blocks) can be employed to avoid slack. In
the latter case at a rudder angle of 39-42°, a trifling difference in the tension will
remain, but in the practice, even when steel wire ropes are employed, this tension
can be considered as an even tension for all positions of the helm.
The ends of the standing parts can be fastened either to a common fixed point
(Sheet II., Figures 1 and 2) or single to convenient places.
Figure 3 (Sheet II.) shows the arrangement of loose pin blocks turning on a
bolt at the head of the tiller, which may be used just as well as fixed pin
blocks.
Sheet III. shows a third arrangement of the rope for avoiding the slack, applicable
for angles not larger than 35-38°. Instead of hauling tight both standing parts
(Sheets I. and II.) only one is hauled tight (always that one wherein the "slack
is formed), by the interference of a turning disc or a fixed curved piece M. The
point for fastening this disc or sheave or fixed piece M will be found by putting the
helm amidships in the above described manner, then putting it over to port and
pressing the sheave or piece M in the middle line forward along the loose standing
part till the slack is made up.
The advantages of the described steering apparatus, compared to the known
arrangement of guiding the pin blocks of the tiller in a straight line, are the
following:
1. For great simplicity in the construction, and therefore less and trifling
repair.
2. Economy in power (tiller supposed to be of the same length). The static
momentum is greater in the described steering apparatus, and grows with the
increase of the rudder angle till it has the whole length of the tiller as its arm of
lever when the helm is put close on board, whilst in the old arrangement the arm
of lever is only 3 of the length of tiller for all the positions of the helm.
The static momentum for the position of the helm amidships is (Figure 3,
Sheet III.)
In the arrangement with tiller blocks in a straight line IF × K.

page_text: For the position of the helm close on board the momentum is,-—
In the old arrangement, IF × K.
In the new arrangement, IP × K.
-
As IP IP¹ at a maximum rudder angle of 42° has nearly 1%, the length of IF,
the force can be consequently 3/, less, that is to say, whenever in the first case, four
parts will be necessary, three will be sufficient for the latter case.
3. The admittance of a rudder angle of utmost size.