IMPROVEMENTS IN FITTING SHIPS' RUDDERS
Year: 1867

page_text: LETTERS PATENT to John Medhurst, of 14, Drummond Road, Bermondsey,
in the County of Surrey, for the Invention of "IMPROVEMENTS IN FITTING
SHIPS' RUDDERS."
Sealed the 3rd March 1868, and dated the 9th September 1867.
PROVISIONAL SPECIFICATION left by the said John Medhurst at the
Office of the Commissioners of Patents, with his Petition, on the 9th
September 1867.
I, JOHN MEDHURST, of 14, Drummond Road, Bermondsey, in the County of
Surrey, do hereby declare the nature of the said Invention for "IMPROVEMENTS
IN FITTING SHIPS' RUDDERS," to be as follows:-
This Invention has for its object improvements in fitting ships' rudders.
Some sure and safe mode whereby the rudders of ships may be unshipped
and shipped for repairs when at sea is much needed, many disasters have
occurred in consequence of ships' rudders breaking and becoming useless.
According to my Invention I provide at the stern of the ship a rudder trunk
of such a size that the rudder can be raised up on to the deck through it, and
afterwards again lowered into its place, and in place of fixing the "braces" or the
sockets which receive the pintels of the rudder to the stern post as is usual
I make them capable of moving up and down a guide fixed on the stern post.
This guide I prefer to be a casting or forging fixed to the stern post and with
a dovetailed or under cut groove in it, and the braces are formed so as to fit
into this guide and be securely held by it. The pintels and braces are

page_text: modified in form so that they cannot escape the one from the other. I
prefer to make them to form with each other ordinary binge joints. When
the rudder is in its place the upper end of the trunk may receive a chock or
filling piece.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Medhurst in the Great Seal Patent Office on the 9th
March 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
MEDHURST, of 14, Drummond Road, Bermondsey, in the County of Surrey,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Ninth day of September, in the year of our Lord
One thousand eight hundred and sixty-seven, in the thirty-first year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Medhurst, Her special licence that the said John Medhurst,
my executors, administrators, and assigns, or such others as I, the said John
Medhurst, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
FITTING SHIPS' RUDDERS," upon the condition (amongst others) that I, the said
John Medhurst, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and seals, should particularly describe
and ascertain the nature of the said Invention, and in what manner the same
was to be performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date of the
said Letters Patent.
NOW KNOW YE, that I, the said John Medhurst, do hereby declare
the nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, that is to say :-
This Invention has for its object improvements in fitting ships' rudders.
Some sure and safe mode whereby the rudders of ships may be unshipped
and shipped for repairs when at sea is much needed, many disasters have
occurred in consequence of ships' rudders breaking and becoming useless.

page_text: According to my Invention 1 provide at the stern of the ship a rudder trunk
of such a size that the rudder can be raised up on to the deck through it and
afterwards again lowered into its place, and in place of fixing the "braces
the sockets which receive the pintels of the rudder to the stern post as is usual
I make them capable of moving up and down a guide fixed on the stern post.
This guide I prefer to be a casting or forging fixed to the stern post and with
a dovetailed or under cut groove in it, and the braces are formed so as to fit
into this guide and be securely held by it. The pintels and braces are
modified in form so that they cannot escape the one from the other. I
prefer to make them to form with each other ordinary hinge joints. When
the rudder is in its place the upper end of the trunk may receive a chock
or filling piece, or a hinge port may be fitted at the bottom of the trunk and
secured by a lashing, the top of the trunk being fitted with a hatch.
And in order that my said Invention may be most fully understood and
readily carried into effect I will proceed to describe the Drawings hereunto

page_text: the form to which the woodwork of the rudder is fashioned; it is such as will
be seen as to produce a nearly flush surface with the outside of the pintels
and their eyes, so that the binge pins cannot work up out of their places.
The lowest brace b¹ is fixed to the stern post as has heretofore been the custom,
and the lowest pintel c¹ of the rudder is also of the ordinary form, so that the
casting a may terminate immediately under the third pintel of the rudder
when in position; the weight of the rudder is taken by the brace b¹ assisted
it may be and as is usual by a dumb cleat fixed to the stern post on which the
pintel c' of the rudder rests. When the rudder trunk is deep, as may be the
case in a vessel having a full poop, the guide groove for the moveable braces
should be continued above the casting a, it may conveniently be formed in the
stern post, the wood being cut away to form it, and the groove being then
lined with sheet metal.
Figure 5 is a side elevation of the stern of a ship corresponding with
Figure 1, but here the rudder is shown in process of being lowered into its
place through the rudder trunk. In this operation the rudder is hauled by
tackle into an upright position over the rudder trunk and carefully steadied
by guy ropes; it is then gradually lowered, and the braces in succession
entered into the guide groove in the stern post. In order to fill the guide
groove
in the casting a to keep it clean and prevent the adhesion of marine
animals and vegetables, cakes of tallow and stearine may be used advantageously;
they are cast to form and cut off to the lengths required; these cakes are
entered into the guide groove between the braces as the rudder is lowered;
these cakes are unnecessary where the groove is not of iron. Fibre such as
coir or other cheap fibre should be mixed in with the tallow and stearine so
that the cakes may not readily break or crumble. In order that the rudder
may not rise when struck by a sea a turned metal ring is shrunk upon
its head at the level of the deck. Over this ring an exterior ring is fitted
which at the bottom has a flange on the outside by which it is bolted down to
the deck, and at the top an internal flange overlapping the upper end of the
ring on the rudder head, this flange ring is bolted down after the rudder has
been shipped, and it is removed prior to unshipping it.
It is not essential that the guide fixed to the stern post to lead the braces to
their position should be of groove form it may be a projecting guide, and Figure 6
shows a transverse section of such an arrangement, in this case the braces b, b, are
made with horns to embrace the guide. A side view of one of these braces is
shown at Figure 7.
Figure 8 is a side elevation of the stern of an iron ship fitted according to
my Invention. The guide a on the stern post is here made of inou either a

page_text: forging or a malleable casting and it is rivetted to the iron stern post. A trans-
verse section through this piece a is shown at Figure 9, and the corresponding
braces, and pintels c are also represented. In iron ships also the projecting
guide may be substituted for the guide groove, as is shown in the transverse
section Figure 10.
In witness whereof, I, the said John Medhurst, have hereunto set my
hand and seal, this Sixth day of March, in the year of our Lord One
thousand eight hundred and sixty-eight.
J. MEDHURST. (L.S.)