Improvements in or relating to Coast and similar Defences.
Year: 1889

page_text: Date of Application, 18th June, 1889-Accepted, 20th July, 1889
COMPLETE SPECIFICATION.
Improvements in or relating to Coast and similar Defences.
I, THOMAS RAFTERY, of 206 Broadway, New York, N.Y., United States of
America, Counsellor at Law, 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 :-
This invention relates to coast, river and harbour defences.
The object is to produce a defence in the nature of an obstruction to navigable
waters, which, while in the highest degree efficient against any attempt on the part
of those opposed to it to pass it, shall be capable, on the part of those employing it,
both of being readily opened or put out of position when it is desired not to impede
navigation, and of being readily shut, replaced or put into position when it is desirable
to obstruct.
With these objects in view the invention consists in a boom capable of being
readily opened and closed, constructed in two or more attachable and detachable
sections whereby it may readily be removed into or out of position; the whole
constituting what be termed a harbor-gate, raft-gate or gate-boom.
may
Fig. 1 is a plan view of the entire boom and surroundings; showing the boom
capable of detachment intermediately; Fig 1ª is a similar view but showing the
boom capable of detachment at an end.
Fig. 2 is a view in side elevation of one abutment and parts of two sections of
the boom.
Fig. 3 is a plan view of a portion of one section.
Fig. 4 is a view in side elevation showing the mode of attachment of a chain to
a log, that is by a half hitch.
Fig. 5 is a plan view with one of the chains and part of another fully drawn and
the position of the others indicated.
Fig. 6 is a plan view with two joining chains fully drawn and the position of
the others indicated.
There are several methods of guarding harbors now in vogue.
One is to extend chains across the narrowest parts of the entrance; but this impedes
navigation, and, owing to the great weight of the chains, it is difficult to keep them
in their entire length near enough to the surface; while moreover by reason of the
facilities for lifting and cutting them now possessed by modern war-ships their purpose
is easily obviated.
Another method is to extend a permanently fixed floating boom across the channel ;.
but such a boom impedes or blocks navigation, wants requisite strength to resist being
broken by concussion, is subject to be torn asunder by shot and may often be depressed
or jumped.
To overcome these objections I have devised a construction at once simple and
feasible and capable of any required strength and which may be called a gate-boom
or raft-boom with raft gates.
The invention is to be used not as a substitute for torpedoes and forts, but as an
aid to these, being employed especially under the aid of a fort or forts.
At a suitable distance beyond the inside of each fort at a suitable channel f
construct a strong stone abutment, built mostly underground and within this fasten
securely one or more, preferably four, large and strong chains and in addition
one or more preferably four, strong wire cables. Hereto I attach one or more,
preferably four, logs or bundles of logs, of suitable size, say of six feet in
diameter, and of thirty feet in length each log or bundle being provided with one or

page_text: more eye-bolts or ring-bolts on each end, and on its under surface with a perforation
from top to bottom about four feet from each end and with a peripheral groove or
collar near each perforation.
Each chain from the abutment passes to a log, passes upward through a ring bolt
at the end then along the upper surface to the perforation, then down through the
perforation then around the log at the groove or collar in a half hitch with the bight
underneath then along the under surface of the log through the ring bolts to the
other perforation then upward through the perforation, then around the log with a
half hitch to the bight on the upper side.
Each wire cable from the abutment passes to a log and is fastened to it, securely
holding the log by a timber hitch.
The boom is constructed in sections, preferably of four logs, or bundles of logs,
each, and in the manner above described the end sections will be flexibly but strongly
attached to the shore.
Other sections may be added to both or either end sections as follows;-The chains
from the logs will be crossed and each will pass to a log in corresponding position on
the opposite side, in this manner additional sections may be added at will, it being
understood that the fastening of the chains to and upon the additional sections will
be in manner similar to that of the first section. The cross chains are beneath the
surface of the water at the under portion of the logs. In addition to these at the
upper portion of the logs there are wire cables passing directly from log
to iog.
By the manner of attachment of chains and cables great strength is given to the
entire structure; and by the method of joining the sections not only is great resistance
presented to any concussive force brought to bear between them but sufficient
resiliency is afforded to give them tendency to come together and thus to bring a
crushing force to bear laterally upon the assaulting object thus also entangling it,
the momentum of the adjoining sections aiding in these respects. The purposes of the
double attachment of the boom at the shores is to give increased strength as most of
the pressure in case of an attempt to force the boom would fall bere. The logs
support the chains and so forth and these bear down the logs so that very little
target surface is offered.
A general objection to booms is that when once placed in position they present a
serious obstruction also to those employing them and with a boom constructed as
above described with its exceeding strength the objection might be even greater; but
to obviate this I make my boom capable of being parted intermediately that is of being
opened and shut one or more parts being then extended and moored or anchored
along shore.
To bring the boom into position it will only be necessary to tow the free ends
together or haul them together from shore and to fasten the boom in position I employ
a simple but very effective device in the nature of a cable bend; that is to say I form
of the projecting ends from the free ends of the meeting sections a bend consisting of
a loop a half-bitch and another half hitch and fasten the free part of the chain
sufficiently near its end to the standing or first position of the chain by whipping or
otherwise the chain itself being hooked, anchored or concealed in any suitable
manner.
When the boom is capable of being parted at either shore and re-attached the
wire cables will be fastened to the logs as before described.
With the construction above described it is not likely that any attempt would be
successful to submerge or jump the boom; but for additional security, 1 employ one
or more, strong and flexible wire cables which pass beneath some of the sections
preferably at the centre and are wound upon cylinders on the shore. The winding
of the cable or cables will elevate the boom as desired.
up
I may employ several booms side by side.
As my boom will be immediately under the guns of a fort it is obvious that there
could be no successful attempt to blow it up by dynamite or otherwise. The boom

page_text: itself.
propony given by electricity or Otherwise and be wen protected as the fort
In the drawings
A designates the boom formed in sections; B the section; C the abutments and D
one or more forts. The sections are made up of one or more logs or bundles of logs b
properly secured together in any suitable manner. The logs are perforated at b¹
and may he grooved or provided with collars at 6 and have one or more eye or ring
bolts at each end and one or more eye or ring bolts along the under surface of
each. The chains from the abutments are designated by c and the half hitches formed
by them on the logs at c¹, the extension of the chains on the surfaces of the logs
being marked and their crossings between sections . The wire cable from the
abutments to an end section of the boom are marked c being attached each to a log,
by a timber hitch c. The cable bends are designated at and c' is the cable for
supporting the boom against depression this cable to be wound up for use on a drum
or drums and to be removed or parted when the boom is to be swung open.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what 1
claim is :-
1. A gate boom or raft gate made in two or more parts detachably connected
consisting of buoyant sections flexibly joined the parts capable of being swung to
open or close the boom.
2. The combination with abutments of a gate-boom or raft gate consisting of
buoyant sections, flexibly connected the boom being made in two parts detachably
joined each part being capable of being swung.
3. The combination with a boom made in sections flexibly joined of a supplemental
cable joined to the sections and means for pulling upon the cable substantially as and
for the purpose set forth.
4. The combination with a boom made in one or more parts of chains joined by
fastening in the nature of a cable bend as shown and set forth.
5. The combination with an end section of a boom of an abutment and chains and
cables the chains and cables being firmly fixed in the abutment, and each chain being
attached to a log by a half bitch and each cable by a timber hitch substantially as
described.
6. In a sectional boom the combination of an end section formed of one or more
logs or bundles of logs each provided with a perforation of an abutment and of one or
more chains each chain passing to the upper surface of the log down through the
perforation then being formed in a half hitch around the log and passing on along
the under surface of the log substantially as set forth.
7. In a sectional boom the combination of an end section formed of one or more
logs or bundles of logs each provided with two perforations of an abutment and of one
or more chains each chain passing to the upper surface of the log to the second per-
foration then up through this perforation then formed in a half hitch around the log
and passing on along the upper surface of the log substantially as described.
8. In a sectional boom the combination of an end section formed on one or more
logs or bundles of logs the logs of each section being securely lashed or banded
together each log provided with two perforations and with one or more circumferential
grooves or collars of an abutment and of one or more chains each chain being securely
fastened to the abutment and passing to a ring bolt fixed in the log then over or under
the log to the nearest perforation then through this perforation and around the log in
a half hitch then along the log either guided or not by eye or ring bolts then through
the other perforation to the opposite side of the log then around the log in a half
hitch and then along the log to another eye or ring bolt substantially as
described.
9. In a boom formed of sections the combination with the sections of chains and
cables the chains being crossod and the cables being fastened to their respective
logs substantially as described.

page_text: 10. A gate boom or raft gate made in one or more detachable parts formed of
buoyant sections flexibly joined by cables and cross chains the whole boom or any
part capable of being swung to open or close.
'
Dated this 18th day of June 1889.
W. P. THOMPSON & BOULT,
Agents.