Improvements in Propelling Canal Boats or other Vessels Navigating Shallow Water.
Year: 1889

page_text: Date of Application, 24th June, 1889
Complete Specification Left, 24th Mar., 1890-Accepted, 26th Apr., 1890
Improvements in Propelling Canal Boats or other Vessels
Navigating Shallow Water.
1, WALTER JAMES GRIFFITHS of 22 Annandale Road Greenwich in the County of
Kent, Mechanical Engineer, do hereby declare the nature of this invention to be as
follows:-
These improvements relate to propelling Canal Boats by means of the frictional
resistance on the bottom of the canal of an endless chain passing from bow to stern
beneath the boat and then back again from stern to bow over the boat.
Across the bow of the boat a shaft is placed having at one end a chain pulley with
projections in the rim to prevent the chain slipping, at the stern is a pulley the lower
part of which is level with the bottom of the boat, and which is carried by a suitable
bracket attached to the dead wood, another pulley attached to the stern above water
so as to keep the chain clear of the hull and at short intervals between this and the
chain-wheel at the bow rollers or small pulleys are arranged to support the chain in
passing along the boat, these being preferably close to one of the sides of the boat as
they are then out of the way of the cargo, and the water and mnd brought up by the
chain can be easily made to drain off overboard.
The engine is placed in the boat near the bow and a short shaft connects it with a
bevel wheel gearing into another on the shaft across the bow on the end of which the
chain-wheel is fixed. The engine may be attached to the boiler so that both may be
readily taken out of the boat for repairs or other reasons.
The endless chain descends from the chain-wheel at the bow into the water.and
ascends over the pulleys at the stern, as the power is exerted at the bow the slack of
the chain is kept in the water: the length of the chain is arranged so that in the
normal depth of the canal there is just enough to descend vertically from the chain-
wheel to the bottom of the canal, the chain lies on the bottom until approaching the
stern it rises in a catenary curve to the lower pulley from which it passes over the
upper pulley and along the rollers to the chain-wheel again.
If at any place the depth of water should be greater the chain will then assume a
catenary curve at the bow as well as at the stern and the length lying on the bottom
of the canal will be shorter, but owing to the chain-wheel at the bow being above the
level of the top of the boat and the stern pulley level with the bottom, their difference
in height will I find enable the chain to suit itself to such variations in the depth as may
be met with in a canal without the length remaining on the bottom becoming so short
as to cause much loss of efficiency in the propulsion.
The greatest pull on the chain due to the power exerted by the engine ought to be
kept rather less than that which would overcome the friction and cause the chain to
drag along the bottom; in passing through locks, in descending the boat could propel
itself in and out, but in ascending when the boat had to go out of the lock the depth
of water in the lock would prevent the chain touching the bottom, and in order to
enable the boat to pass out I propose to use a rope of about 3rds of the length of the
boat with a hook at one end, this hook being inserted in one of the links of the chain
near the bow and the other end of the rope secured by a turn or two round a post on
the bank the engine could be started and as the rope would prevent the chain slipping
on the lock-sill the boat would pass out of the lock. The rope could be cast off the
post when rather more than half the boat had passed out and when the hook came up
at the stern it could be removed from the chain, or a disengaging hook could be used
that would release itself when the pull was off.
The boat should be as long as the canal locks would allow, chain being used on
account of its weight and the stress very small in proportion to what good chain of

page_text: the section would stand, condemned cables would be sufficiently good, or a cheap
description of chain having alternate heavy links of cast iron could be used.
For canals of small section I consider the arrangement well suited, as the screw or
any propeller depending on the reaction of the water is least efficient in those and
they are most injured by the wash of the banks caused by the screw.
Boats fitted in the above manner could of course be used to tow others as well as
propel themselves.-
Dated this 22nd day of June 1889.
COMPLETE SPECIFICATION.
Improvements in Propelling Canal Boats or other Vessels
Navigating Shallow Water.
I. WALTER JAMES GRIFFITHS of 22 Annandale Road Greenwich in the County of
Kent, Engineer 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 :-
These improvements relate to propelling canal boats by means of the frictional
resistance on the bottom of the canal of an endless chain passing from bow to stern
beneath the boat and then back again from stern to bow over the boat.
Figs. 1, 2 and 3 are side view, plan and end view of a boat fitted in this manner.
Across the bow a shaft A is placed having at one end a chain pulley B with pro-
jections in the rim to prevent the chain slipping, at the stern is a pulley C the lower
part of which is level with the bottom of the boat, and which is carried by a suitable
bracket attached to the deadwood, another pulley D is attached to the stern above
water so as to keep the chain clear of the hull and at short intervals between this and
the chain-wheel at the bow rollers or small pulleys E, E are arranged to support the
chain in passing along the boat these being preferably close to one of the sides of the
boat as they are then out of the way of the cargo, and the water and mud brought up
by the chain can be easily made to drain off overboard.
The engine G is placed in the boat near the bow and a short shaft connects it with
a bevel wheel gearing into another on the shaft A across the bow on the end of which
the chain pulley B is fixed. The engine may be attached to the boiler so that both
may be readily taken out of the boat for repairs or other reasons.
The endless chain descends from the chain wheel A at the bow into the water and
ascends over the pulleys at the stern, as the power is exerted at the bow the slack of
the chain is kept in the water: the length of the chain is arranged so that in the
normal depth of the canal there is just enough to descend vertically from the chain-
wheel to the bottom of the canal, the chain lies on the bottom until approaching the
stern it rises in a catenary curve to the lower pulley C from which it passes over the
upper pulley D and along the rollers to the chain-wheel again.
If at any place the depth of water should be greater the chain will then assume a
catenary curve at the bow as well as at the stern and the length lying on the bottom
of the canal will be shorter, but owing to the chain wheel B at the bow being above
the level of the top of the boat and the stern pulley C level with the bottom, their
difference in height will I find enable the chain to suit itself to such variations in the
depth as will probably be met with in a canal without the length remaining on the
bottom becoming so short as to cause much loss of efficiency in the propulsion.
Fig. 4 shows a 60 ft. boat suited to a canal of 5 ft. minimum depth, the position
the chain would assume in depths of 8 feet and 11 feet is shown and also the extreme
position it could reach. The curve in Fig. 5 shows the length of chain that would lie
on the bottom at each depth, the greatest pull on the chain due to the power exerted
by the engine ought to be kept rather less than that which would overcome the
friction and cause the chain to drag along the bottom, and I find by experiment a
pull equal to one half of the weight of chain lying on the bottom may safely
be used.

page_text: In passing through locks, in descending the boat could propel itself in and out, but
in ascending when the boat had to go out of the lock the depth of water in the lock
would prevent the chain touching the bottom, and in order to enable the boat to pass
out I propose to use a rope of about 3rd of the length of the boat with a hook at one
end, this hook being inserted in one of the links of the chain near the bow and the
other end of the rope secured by a turn or two round a post on the bank the engine
could be started and as the rope would prevent the chain slipping on the lock-sill the
boat would pass out of the lock. The rope could be cast off the post when rather
more than half the boat had passed out and when the hook came up at the stern it
could be removed from the chain. Fig. 6 shows the boat leaving a lock by means of
the rope, should the system be much used however a platform in the lock could be
arranged to rise with the water and as the chain would rest on that the rope would
not be necessary.
The boat should be as long as the canal locks would allow, chain being used on
account of its weight and the stress very small in proportion to what good chain of
the section would stand, condemned cables would be sufficiently good or a cheap
description of chain having alternate heavy links of cast iron could be used.
For canals of small section 1 consider the arrangement well suited, as the screw or
any propeller depending on the reaction of the water is least efficient in those and
they are most injured by the wash of the banks caused by the screw.
Boats fitted in the above manner could of course be used to tow others as well as
propel themselves.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
The propulsion of canal boats by the frictional resistance on the bottom of the canal
of an endless chain which is rendered capable of adjusting itself to moderate
variations in the depth of the canal by the pulleys on the boat being arranged
substantially as hereinbefore described and shown on the drawings annexed.
Dated this 24th day of March 1890.
W. J. GRIFFITHS.