IMPROVEMENTS IN DAVITS FOR LOWERING SHIPS BOATS
Year: 1883

page_text: LETTERS PATENT to Robert Hudson, Blacksmith, John Grantham, Plumber
and John Henry Broker, Master Mariner, all of Blyth, in the County of
Northumberland. for an Invention of IMPROVEMENTS IN DAVITS FOR
LOWERING SHIPS BOATS
"
"
PROVISIONAL SPECIFICATION left by the said Robert Hudson, John
Grantham, and John Henry Broker at the Office of the Commissioners of
Patents on the 21st September 1883.
ROBERT HUDSON, Blacksmith, JOHN GRANTHAM, Plumber, and JOHN HENRY
BROKER, Master Mariner all of Blyth in the County of Northumberland,
"IMPROVEMENTS IN DAVITS FOR LOWERING SHIPS BOATS
Our invention relates to what are called swinging davits or such as, from a fixed
fulcrum, can be projected over the ships side or fall backward "inboard" so that the
boat rests between them and the bulwarks of the ship.
Each davit consists of an upright (made in one or more pieces) and inclining
inboard" hinged at its lower end at level of deck and having at its upper end
an arm curved "outboard" to an extent sufficient to bring it exactly over the
centre of the boat when resting on the "chocks." The outer end of this arm is
made of a peculiar hooked or curved form and receives a crosshead from which
the boat is suspended direct, which we prefer. A wire or other rope or a chain
leads from the top of crosshead on each davit by suitable guide sheaves to a winch,
which stands between the davits on ships deck, having its main barrel so arranged
as to receive the rope or chain from each davit upon it so that it will hoist or
lower from both davits simultaneously. This winch may be single or double
acting and must be fitted with an efficient brake. The hinged arm of each davit
when the boat is on the "chocks" rests against the inclined back of a frame which
is bolted to deck and to the bulwarks, which frame carries a guide or guides, on
or between which the hinged arm moves when swinging "outboard" and which
protect it from side strains, and when it has reached its extreme position "outward "
it rests at the junction of this guide or guides with the bulwarks, being supported
[Price 6d1

page_text: in this position entirely between this point and its hinged lower end. These
frames may have attached to them brackets to receive or to form the "chocks" in
which the two ends of the boat are to rest.
When the boat is resting in the "chocks" and is required to be put out, &
slight winding of the ropes or chains upon the winch barrel draws the crossheads
up the hooked or curved part of the upper arm of each davit and raises the boat
to an extent sufficient to allow the "chocks" to be knocked clear. The winch
being now released and under the control of the brake, the crossheads descend in
the hooked curved part of the upper arms and increase the leverage of the banging
weight of the boat so as to cause the davits to swing "outboard" automatically
with the boat and crew, controlled by the brake on winch until they rest at the
junction of the guides with the bulwarks when the barrels of winch being further
allowed to run by the brake the boat is lowered into, or nearly into the water,
clear of side of ship and may be detached or disengaged by any of the usual well
known means.
When the boat is to be lifted out of the water it is attached at
each end to a hook or shackle on lower end of crosshead and the winch being put
in gear the ropes or chains to each davit head are wound upon the barrel raising
the boat until the crossheads reach the hooked upper part of the curved ends and
the further action of the winch now raises the boat and also brings it inboard, by
the radial action of the davits on their hinged lower ends, till the boat is over the
"chocks" into which it seats itself when the crossheads are allowed to descend in
the hooked or curved ends by lowering at the winch the davits now resting against
the inclined backs of their frames when safety pins may be inserted. When blocks
and tackle are preferred the upper block is attached to the crosshead, the action
of which, in the hooked or curved end of arm, is the same as above described, but
the crosshead is not able to disengage itself from the hooked or curved end, and
the rope or chain to the winch passes through and between the two blocks in the
usual way. For simplicity and efficiency we prefer to dispense with blocks and
adopt the single rope or chain

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Robert Hudson, John Grantham, and John Henry Broker in the
Patent Office on the 21st March 1884.
ROBERT HUDSON Blacksmith JOHN GRANTHAM Plumber and JOHN HENRY
BROKER Master Mariner all of Blyth in the County of Northumberland
IMPROVEMENTS IN DAVITS FOR LOWERING SHIPS BOATS.
Our invention relates to what are called swinging davits or such as, from a
fixed fulcrum can be projected over the ships side or fall backward "inboard" so
that the boat rests between them and the bulwarks of the ship
Each davit consists of an upright (made in one or more pieces) and inclining
"inboard" hinged at its lower end at level of deck and having at its upper end
an arm curved "outboard" to an extent sufficient to bring it exactly over the
centre of the boat when resting on the "chocks." The outer end of this arm is
made of a peculiar hooked or curved form and receives a crosshead from which the
boat is suspended direct, which we prefer. A wire or other rope or a chain leads
from the top of crosshead on each davit by suitable guide sheaves to a winch,
which stands between the davits on ships deck, having its main barrel so arranged
as to receive the rope or chain from each davit upon it so that it will hoist or
lower from both davits simultaneously. This winch may be single or double
acting and must be fitted with an efficient brake. The hinged arm of each davit
when the boat is on the "chocks" rests against the inclined back of a frame
which is bolted to deck, which frame carries a guide or guides, on or between
which the hinged arm moves when swinging "outboard" and which protect it
from side strains, and when it has reached its extreme position "outboard" it rests
in this guide or guides, being supported in this position entirely between this point
and its hinged lower end. These frames may havo attached to them brackets to
receive or to form the "chocks" in which the two ends of the boat are to rest
When the boat is resting in the "chocks" and is required to be put out, a
slight winding of the ropes or chains upon the winch barrel draws the crossheads
up the hooked or curved part of the upper arm of each davit and raises the boat
to an extent sufficient to allow the "chocks" to be knocked clear. The winch
being now released and under the control of the brake, the crossheads descend in
the hooked curved part of the upper arms and increase the leverage of the hanging
weight of the boat so as to cause the davits to swing "outboard" automatically
with the boat and crew, controlled by the brake on winch until they rest upon
the guides, when the barrels of winch being further allowed to run, by the brake,
the boat is lowered into, or nearly into the water, clear of side of ship and may
be detached or disengaged by any of the usual well known means. When the
boat is to be lifted out of the water it is attached at each end to a hook or shackle
on lower end of crosshead and the winch being put in gear, the ropes or chains
to each davit head are wound upon the barrel, raising the boat until the crossheads
reach the hooked upper part of the curved ends and the further action of the
winch now raises the boat and also brings it "inboard," by the radial action of
the davits on their hinged lower ends, till the boat is over the "chocks" into
which it seats itself when the crossheads are allowed to descend in the hooked or
curved ends by lowering at the winch, the davits now resting against the inclined
backs of their frames when safety pins may be inserted.
In exceptional cases of unusually large and heavy boats blocks and tackle may
be arranged to increase the lifting power without affecting the principle of the
invention but we do not anticipate any need for this and prefer to dispense with
blocks and adopt the single rope or chain

page_text: DESCRIPTION OF DRAWINGS
The accompanying drawings illustrate the mode in which our invention may be
carried into practical application, but the modes of application will require to be
varied to meet the different classes of vessels to which the davits are to be fitted
the essential features being the same
Figure 1 is an end view of a ship fitted with davits on main deck the boat
resting on the chocks on bridge deck the davits being shewn in their "inboard"
position
Figure 2 is an end view of the same with the davits swung fully outboard the
boat ready for lowering into the water from their projecting ends
Figure 3 is a view looking from deck seaward on side of boat which is resting in
chocks on bridge deck as in Figure 1
A A are the davits hinged on fulcrums B B in frames C C fixed to main
deck; DD are the curved jaws formed in the projecting upper ends of davits A A;
EE are ropes or chains leading from the barrel or barrels of a winch F fixed to
deck between the davits and carried by four leading sheaves (one of which G is so
placed either on top of framing C as shewn or other convenient point, in relation
to the top end of the davit as to give the rope leverage to bring the davit inboard
from the position shown on Figure 2.) to head of davits and thence to cross-
heads H H shewn in Figure 1 resting in lower portion of curved jaws D D and in
Figure 2 clear of jaws to lower with the boat. The boat being in chocks as in
Figure 1 a turn of the winch lifts her clear (the crossheads H H sliding up the
curve and against the upper portions of jaws) when the hinged flaps are knocked
over and the weight of the boat causes the crossheads to slide down and rest in the
lower portions of jaws and the davits now descend outboard on their fulcrums,
their motion being controlled by the winch under the power of the brake, till they
reach the extreme position shewn on Figure 2, when further lowering takes the
boat into the water or near enough to be detached. In raising the boat the winch
is put into operation winding both ropes equally on its barrel or barrels till the
crossheads come into the curved jaws against the upper portions of which they
engage and the further winding of the winch brings the boat inboard, by the davits
swinging on their fulcrums, till it is again over the chocks into which it seats itself
In some cases where the construction of the ship will allow we propose to
dispense with the framing C so far as relates to the sloping back and front parts
using only a deck plate and the fulcrum piece B, the back rest for the davits when
inboard as in Figure 1 being provided in the bridge and the front rest when out
board as in Figure 2 being formed in the side structure of the bridge or on the
Bulwarks, the main leading sheaves G G being then fixed in some convenient
position with regard to the leverage of the ropes to raise the ends of davits from
their outboard position Figure 2.
Having now described our invention and shewn one mode of applying it we
declare what we consider novel and claim as our invention secured to us by Letters
Patent to be
1st The construction and application of swinging davits so that the weight of
the boat when, "inboard" and clear of the chocks, will automatically cause them
to swing "outboard" on their fulcrumns substantially as shewn and described.
2nd With such swinging davits the use of a single rope or chain without blocks
and tackle, from each davit to a winch upon the barrel or barrels, of which such
ropes or chains will be equally coiled or uncoiled so as to raise the boat equally at
both ends and to bring the davits and boat "inboard" or to control their
automatic swinging outboard and the lowering of the boat into the water
substantially as shewn and described
3rd In swinging davits the construction of curved jaws, projecting from their
upper ends, of such a form that crossheads attached to the ends of the ropes or
chains will engage with or rest in the lower portions of the jaws, when the boat is

page_text: clear of the chocks, thus causing the weight of the boat to automatically cause the
davits to swing outboard and when they reach their extreme position to allow the
crossheads to clear the jaws, and the boat to be lowered into the water, said
crossheads when the boat is hoisted out of the water again engaging with the upper
portions of jaws and causing the davits to be brought inboard with the boat and on
to the chocks substantially as shewn and described
4th The combination of parts forming the apparatus as a whole consisting of the
davits A A working on fulcrums BB with curved jaws D D in their projecting
upper ends, ropes or chains E E leading from winch F over suitable guide sheaves
and by main sheaves G G (so placed as to cause the ropes, when davits are
outboard, to bring them inboard) over the heads of davits to crossheads HH
arranged to engage with or disengage from jaws D D and thereby to effect
automatic action of the davits to swing inboard or outboard and to lower or raise
the boat into or out of the water together constructed and operating substantially
as shewn and described
In witness whereof we the said Robert Hudson and John Grantham on behalf
of ourselves and the said John Henry Broker have hereunto set our hands and
seals this twentieth day of March in the year of our Lord one thousand eight
hundred and eighty four.
Witness:
T. J DANSON F. Inst P.A
Consulting Engineer & Patent Agent
Newcastle on Tyne
ROBERT HUDSON (L.S.)
JOHN GRANTHAM (LS.)