Improvements in Hopper Dredgers.
Year: 1885

page_text: Improvements in Hopper Dredgers.
I, ANDREW BROWN of London Works Renfrew in the County of Renfrew
Engineer and Shipbuilder do hereby declare the nature of my said invention for
"IMPROVEMENTS IN HOPPER DREDGERS" to be as follows:-
Said invention has for its object, to facilitate the propulsion and navigation of
Hopper Dredgers, backwards and forwards in Docks and narrow channels to avoid
the necessity of turning the Vessel round, this is effected in an improved and
advantageous manner by providing the Vessel with the means of propulsion and
steering at the forward or Bow end of the Vessel in addition to the usual propellers
and steering appliances at the stern.

page_text: Improvements in Hopper Dredgers.
1, ANDREW BROWN of London Works Renfrew in the county of Renfrew,
Engineer and shipbuilder do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
My invention has for its object to facilitate the propulsion and navigation of
hopper dredgers, backwards and forwards in docks and narrow channels, to avoid.
the necessity of turning the vessel round.
This is effected in an improved and advantageous manner by providing the
vessel with the means of propulsion and steering at the forward or bow end of
the vessel, in addition to the usual propellers and steering appliances at the stern.
The accompanying four sheets of drawings shew various modes of applying my
invention to a hopper dredger.
t
Figures 1 and 2, Sheet 1 are respectively a longitudinal section and a plan of a
hopper dredger having my improvements applied thereto.
Figures 3 and 4, Sheet 2 are respectively a longitudinal section and a plan of a
hopper dredger having my improvements applied thereto, in a modified form to that
shewn in Figures 1 and 2.
Figures 6 and 7 Sheet 3, Figures 8 and 9 Sheet 3, Figures 10 and 11 Sheet 4
and Figures 12 and 13, Sheet 4, are, in each case, respectively longitudinal sections
and plans of hopper dredgers having still further modifications of my improvements
applied thereto.
Figure 5 Sheet 2 is an enlarged view of the bevel gear screw shaft coupling, used
in Figures 3 and 4.
Similar parts of the dredger and apparatus are denoted by similar letters
throughout the drawings.
In Figures 1 and 2 Sheet 1, a hopper dredger with long bucket well W W and
side hoppers H H is shewn. The framing for the ladder traversing gear is also
shewn in Figure 1. E is the boiler and A A are a pair of main engines driving
twin screws S, S, at the stern in the ordinary way, a single rudder R being
provided.
The propeller shafts B B are carried forward of the engines, along each side of
the bucket well and drive another pair of twin screws S¹ S¹ at the bow or well
end of the dredger. The parts B¹ B₁ of the shafts are diverged outwards to keep
the screws S¹ S¹ clear of the bucket well and swivel couplings C, C, are introduced
in the shafts to permit of such divergence. Two rudders R¹ R¹ are provided one at
each side of the well.
The description of Figures 1 and 2 will apply equally to Figures 3 and 4 Sheet 2
with the exception that bevel gearing G G is employed in place of the swivel
couplings C, C, to permit of the divergence of the screw shafts.
Figures 6 and 7 Sheet 3 shew a hopper dredger with bucket well W W and side
hoppers H H provided with a similar arrangement of engines, screws and rudders
to that shewn in Figures 1 and 2, but in this case the screw shafts are parallel
throughout their whole length, thus avoiding the use of the swivel couplings CO
or bevel gears G G.

page_text: Figures 8 and 9 Sheet 3 shew a hopper dredger with a short bucket well W, and
a large central hopper H. In this case as it would be inconvenient to take the
screw shafts through the centre of the hopper a pair of engines A A drive twin
screws S S through shafts B B at one end of the vessel, while a similar pair of
engines A¹ A¹ drive twin screws S¹ S¹ through shafts B¹ B¹ at the other end.
Rudders R, R¹ R¹ are provided as before.
Figures 10 and 11 Sheet 4 shew a hopper dredger with long bucket well W and
side hoppers H H, here the engines A A drive twin screws S₁ S¹ directly through
the shafts B¹ B¹ at the well end of the vessel, while a single screw S is driven at
the other end from the engines by means of the spur gearing J.
Figures 12 and 13 Sheet 4 shew a hopper dredger with a short bucket well W
and large central hopper H, similar to the dredger shewn in Figures 8 and 9.
Twin screws S¹ S₁ at one end and a single screw S at the other end of the vessel
are provided as in Figures 10 and 11 but in order to avoid taking the shafts
through the hopper, the screw S is driven by a separate engine A and the twin
screws S¹ S¹ by separate engines A¹ A¹.
"
The arrangements of separate engines and shafts as shewn in Figures 8 and 9
and in Figures 12 and 13 may equally well be employed in dredgers with side
hoppers of the type shewn in Figures 1 and 2 if desired.
It will be seen that in all cases the two ends of the vessels are made similar to
each other, with the exception of the necessary opening at the well end, so that
they can move with equal facility in either direction. Suitable clutches are provided
to throw the screws in or out of gear as required.
It is obvious that these various screws and rudders not only afford equally good
means of propulsion in either direction, but they also give a very rapid and
effecient means of steering the vessel, and by driving the screws at the ends in
opposite directions the vessel can be turned round upon its centre and within its
own length.
The advantage to a hopper dredger in being able to enter and leave a narrow
channel at equal speed, without being turned round and having quick and powerful
means of steering is obviously very great.
The various ways of applying my invention to a hopper dredger are, as will be
clearly understood, not necessarily confined to the modes shewn in these four sheets
of drawings and described in this specification, but they include the principal ways
in which such invention' would be carried out in practice.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim, is :-
(1.) A Hopper Dredger having the means of propulsion and steering provided
at the forward or bow end of the vessel in addition to the usual propellers and
steering appliances at the stern, substantially as herein shewn and described.
(2.) The combination with a Hopper Dredger, having propellers and steering
appliances at the stern, of propellers and steering appliances at the bow, substan-
tially as herein shewn and described.
(3.) In a Hopper Dredger, the arrangement of propellers at the bow and stern,
whereby the said dredger may be turned around within its own length, substan-
tially as herein shewn and described.
AMBROSE MYALL, C.E.,
Agent for the Applicant.