A SUBSTITUTE FOR AN ANCHOR, WHICH I DENOMINATE A BLOCK ANCHOR
Year: 1819

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
RODGER; of Suffolk Street, Charing Cross, in the County of Middlesex,
Lieutenant in the Royal Navy, send greeting.
WHEREAS His late most Excellent Majesty King George the Third, did,
by His Letters Patent under the Great Seal of the United Kingdom of Great
Britain and Ireland called England, bearing date at Westminster, the Fourth.
day of December, in the sixtieth year of His reign, give and grant unto me, the
said William Rodger, my exors, adñiors, and assigns, His especial licence, full
power, sole privilege and authority, that I, the said William Rodger, my
exors, admors, and assigns, during the term of years therein mentioned, should
and lawfully might make, use, exercise, and vend, within England, Wales,
and the Town of Berwick-upon-Tweed, and also in all His Majesty's Colonies
aud Plantations abroad, my Invention of "A SUBSTITUTE FOR AN ANCHOR, WHICH
I DENOMINATE A BLOCK ANCHOR;" in which said Letters Patent there is con-
tained a proviso that if I, the said William Rodger, shall not particularly
describe and ascertain the nature of my said Invention, and in what manner
the same is to be performed, by an instrument in writing under iny hand and
seal, and cause the same to be inrolled in His Majesty's High Court of
Chancery within six calendar months next and immediately after the date of
the said Letters Patent, that then the said Letters Patent, and all liberties
and advantages whatsoever thereby granted, shall utterly cease, determine, and
become void, as in and by the same, relation being thereunto had, will more
fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
William Rodger, do hereby declare that the nature of my said Invention,,

page_text: and the manner in which the same is to be performed, are particularly
described and ascertained in and by the Drawing hereunto annexed, and the
following the description thereof (that is to say):-
Fig. is a view of a block anchor with its shank turned towards the left.
Fig. 2, a plan of the same.
2.
Fig. 3, a view of the anchor in its middle situation, or in the act of turning
over towards the right,, and as shewn in Fig. 5. Fig. 4, a plan of it in the
situation shewn in Fig. 3.
Fig. 5, a view of the anchor with its shank turned towards the right. Fig. 6,
a plan of the same.
Fig. 7, a front view of the anchor.
Fig. 8, a side view of the shank of the anchor with an elongated stem.
Fig. 9, an edge view of the same. Fig. 10, an edge view of Fig. 8 taken in
front.
Figs. 11 and 12, two views of the shackles.
Fig. 13, an end view of the block part of the anchor inverted, without the
shank. Fig. 14, a plan of the same.
Fig. 15, the bolt and screw nut; Fig. 16, the nut shewn separately; and
Fig. 17 the square head of the bolt.
The same letters referring to the same parts in all the Figures.
A, A, the bills of the shank; B, the eye in the shank for the shackle bolt;
C, the hole in the shank for the connecting bolt; D, the shackle of the shank;
E, the shackle connecting it with the cable; F, F, the edges of the block part
of the anchor; G, the notch, gap, or recess in the block to receive the shank ;
H, H, the holes for the connecting bolt; I, the connecting bolt; K, the
square recess for the head of the bolt I; L, the square head of the connecting
bolt; M, the round recess for the screwed nut N of the connecting bolt I;
O, the crown or after part of the block; P, P, ribs to strengthen the block;
Q, Q, &c., circular holes through the after part of the block to lighten it, and
thereby give a greater preponderance to the edges F, F, or penetrating fore
parts of it, as well for attaching or fastening a buoy rope to it, or through
which holes ropes or chains may be reeved to back it with another anchor;
R, the bolt of the shackle D; S, the bolt of the shackle E; T, Fig. 6, a
swivel, to be used to take the turns or twist out of a hempen cable, which
must be attached or bent to the ring U. If a chain cable be used, the swivel
T and ring U must be taken away, and the end link of the chain cable be
attached to the shackle E.
I prefer to make the shank, on account of its lightness, and for the sake of
strength, of wrought iron or stout gun metal or other tough mixed metals, and

page_text: especially to preserve the sharpness of the bills, points, or edges A, A. The
block may be made of cast iron, for the sake of cheapness.
The principal novelties of this Invention, and on which I found my claim to
a Patent, consist in the introduction of a moveable shank, and in the new forin
which I have given to the block part of the anchor, which has both sides alike,
so as for the edges F, F, to enter the ground at the same angle of inclination,
and thus ensure the anchors acting on whatever side it may happen to fall, as
shewn in Figs. 1 and 5. I do not mean, however, hereby to confine myself to
the particular shapes thereof herein shewn and described, but to avail myself
of any other forms thereof by which a similar effect can be produced. The
particular advantages of this contrivance over the anchors hitherto used will
be best seen by a reference to Figs. 1, 3, and 5, in which the line V, V,
represents anchoring ground of considerable hardness. The block anchor on
reaching it will assume the position of Figs. 1 or 5, with the shank either to
the left or right, according to the direction of the ship. The lower bill or
point of the shank A, being as sharp as the bill of an anchor of the usual form,
will immediately sink into the ground, partly by its own weight and partly by
that of the block, until the edges F, F, of the block come into contact with
the ground; but as the edges F, F, form a line of greater length than the
point of the shank A, they will not begin to enter the ground till the strain
comes upon the anchor, but as soon as the ship or vessel begins to drag it, the
edges F, F, will enter, and continue to penetrate it deeper and deeper, until
it has taken a firm hold, and brings the ship up. In soft ground, however, its
weight will cause it to enter before the dragging commences, a short drag
being sufficient in either case to enable it to attain its greatest power of
resistance, as it will generally bury itself before it has dragged twice its own
length. When used in good anchoring ground, such as mud or clay, the
water is excluded from beneath its broad horizontally extended surface, in
consequence of which the cohesion, when assisted by the pressure of the atmo-
sphere and the weight of the superincumbent water, becomes so great that it
will hold much more than when used in very hard ground or shingle, where
the upward pressure of the water cannot be removed; but in either case I
believe it will hold as much as an anchor of the usual form, and of the same.
weight, including the stock. In the event of the ship going round the block
anchor (without a sufficient strain upon it to turn it round), it will be perceived
that there is not the least danger of fouling it, as is too often the case with
the common anchor, and consequently ships will ride at single anchor with
much greater safety with the former than with the latter, and thus the trouble
and expence of mooring may frequently be avoided, and the loss of time thereby
occasioned be saved. Should the ship go directly over it, it will disengage

page_text: itself from the ground, turn over on its crown, and again take fresh hold,
which is not the case with blocks having the property of holding on one side
only, and which require to be lowered to the bottom with great care and
attention to insure the right side being upwards, and which would merely hold
by their own weight, if upset in the manner I bave described, they having
no tendency to penetrate into the ground but in one position only. These
advantages, together with its compactness, which allows it to be stowed
away in a very small space, and also its cheapness (it being chefly made
of cast iron), will, I firmly believe, contribute to bring the block anchor into
general use.
An anchor made to the Drawing, which is on a scale of one inch to a
foot, would weigh about 15 cwt., nearly 12 cwt. of which would be cast iron.
I have also to observe that in soft ground the block anchor will hold much more
than the common anchor, as the latter derives very little benefit from the
pressure of the water upon it, owing to its fluke or arm lying obliquely to the
borizon, and its surface being small in comparison with the broad horizontally
extended surface of the block anchor. In the event of the block anchor being
found too hard to weigh, which may probably be the case in soft ground, on
account of the great weight of the superincumbent water, and the pressure of
the atmosphere upon it, the stem of the shank may be elongated to any extent,
and as shewn in Fig. 8, which will give it more leverage and power to break
the block part of the anchor out of the ground. .
In witness whereof, I, the said William Rodger, have hereunto set my
hand and seal, this Second day of June, in the year of our Lord One
thousand eight hundred and twenty.