An Improved System of Side Lights for Indicating the Course of Ships and the like.
Year: 1884

page_text: An Improved System of Side Lights for Indicating the Course
of Ships and the like.
I CLARENCE ALFRED LIDSTONE of Calcutta in the East Indies Master Mariner
Licensed Senior Master Pilot Bengal Pilot Service do hereby declare the nature of
my said invention for AN IMPROVED SYSTEM OF SIDE LIGHTS FOR INDICATING
THE COURSE OF SHIPS AND THE LIKE" to be as follows :-
Under the system of side lights at present used by ships and steamers it is
impossible after a vessel's side is sighted to decide within an arc of nearly ten
points the direction of her head.
My present invention consists in supplementing the side lights as a means of
ascertaining within a few points of the compass the course a vessel is steering or
heading when her side lights are visible.
This I effect by placing a second light which I term the course-indicator light
say 15 feet abaft of and parallel to each of the side lights at present in use and so
that they will be cut off in such a way as to show three points red and four white
to port and similarly three points green and four white to starboard.
These additional lights would be distinctly visible only from say three points on
the bow to about two points abaft the beam shutting out simultaneously with the
side lights.
When the white and green lights of the Course Indicator, or the White light of
the Course Indicator and the green side light present themselves to the observer
the white light will be sufficiently clearly defined and distinguishable from the
green on the starboard side as the white is from the red on the port side.
In some positions the lights seen by the observer would be exactly the same as
at present.
When the vessel is on the most dangerous arc advancing nearly end on only the
red side light is seen by the observer.
By the present system the vessel may be heading on any point between South
or West, North West and it is absolutely impossible for the observer to know on
which of these points her head may lay.

page_text: The Course Indicator Light being obscured this shows at once that the vessel is
heading between South and South West by South or within few points to the left
of his line of sight the observer being supposed to head due North.
If the white Light of the Course Indicator is seen in conjunction with the side
light the vessel must be heading more than six and less than 10 points to the left
of the line of sight.
Similar remarks apply in the case of the Green light on the starboard side.
These lights would not interfere in any way with the present system of side
lights and might or might not be utilized by an observer who would have the side
Lights to guide him exactly as at present.
They would when not visible make the present side Lights seen singly serve as
a great danger signal and hence be of much greator significance than they are at
present by indicating at once to the observer that the vessel's head was on the
most dangerous and advancing arcs.
They would when visible and in conjunction with the side light showing either
two red or two green lights become a little danger signal and indicate to the observer
at once that the vessel's head was more than three and less than six points to the
left or right of his line of sight which would be determined by the color of the
lights.
•
They would when a side light and the white light of the Course Indicator were
visible in conjunction become a Caution' signal and indicate to the observer that
the vessel's head was more than six and less than ten points to the right or left as
the case might be of his line of sight.
Under ordinary circumstances (i e fairly clear weather) with this signal showing
there would not be any immediate necessity for action and time might be taken to
watch the strangers movements.
Hence my reason for suggesting the name 'Caution' signal.
It would be impossible for a vessel whose side lights were visible to alter her
course more than three points on the great danger or little danger signal arcs and
more than four points on the caution signal arc without its being indicated by the
lights and would enable an observer to form an opinion regarding any manoeuvre
the vessel might be making such as going about wearing round keeping away or
altering her course more than three points from that which she was steering when
she first sighted her light or lights.
Their introduction could scarcely be the cause of any accident or confusion on
the part of the observer. Vessels approaching nearly end on would still show the
single red or green side light and this would be a signal of great danger. Even
supposing the one vessel were not carrying the Course Indicator Lights their
general use would yet cause greater caution.
Two red lights or two Green lights seen so close together ought to confuse no
one even had he not heard of them. He would know that a red light meant
that the vessel was showing her port side to him and would act as under existing
circumstances.
I have used the terms less than three and less than six points as the Course
Indicator light would begin to show itself faintly about half a point before the
three point line on the great danger and the six point line on the little danger arcs
were opened. This I find would be necessary in order that they should shine
clearly and distinctly over their respective arcs.
It appears impracticable to cut off the light shown from a small lamp without
the use of very long screens placed outside it. This would not be desirable in
a lamp used as a vessel's side light as it would make it cumbersome and easily
injured. The fact of the red or green light of the Course Indicator showing faintly
before its arc opened is rather an advantage than an objection as it would inform
the observer of the actual course within half a point the vessel was steering on
that line.

page_text: If the white and colored light of the Course Indicator were visible at the same
time it would determine her actual course within one point of the six point line.
The Course Indicator lights will not interfere in any way with the present side
lights but act solely as a guide and help to commanders and officers of vessels as.
a Course Indicator and to be used solely for that purpose.
The Lights would probably assist Judges of Marine Courts in arriving at their
decisions in cases of Collision that take place at night by enabling them to
determine more accurately from the evidence the course and manoeuvres of either
vessel prior to the accident.
The extra expense namely the cost of the lamps and placing them in position
would be very small.

page_text: An Improved System of Side Lights for Indicating the Course
of Ships and the like.
I CLARENCE ALFRED LIDSTONE of Calcutta, in the East Indies, Master Pilot
Bengal Pilot Service, do hereby declare the nature of my invention for "AN
IMPROVED SYSTEM OF SIDE LIGHTS FOR INDICATING THE COURSE OF SHIPS AND
THE LIKE and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
-
Under the system of side lights at present used by ships and steamers it is
impossible after a vessels side is sighted to decide within an arc of nearly ten
points the direction of her head.
My present invention consists in supplementing the side lights as a means of
ascertaining within a few points of the compass the course a vessel is steering or
heading when her side lights are visible.
This I effect by placing a second light which I call the course indicator light
15 feet abaft of, and parallel to each present side light to be cut off in such a way
ps to show three points red and four white to port and similarly three points
green and four white to starboard.
These additional lights would be distinctly visible only from three points on the
bow to two points abaft the beam shutting out simultaneously with the side lights.
When the white and green lights of the course indicator, or the white light of
the course indicator and the green side light, present themselves to the observer
the white light will be sufficiently clearly defined and distinguishable from the
green on the starboard side as the white is from the red on the port side.
In diagram B Figures 1 and 2 the light or lights seen by the observer would be
exactly the same as at present.
In Figure 2 the vessel is represented on the most dangerous arc as she is
advancing nearly end on and showing only the red side light.
By the present system the vessel may be heading on any point between South or
West North West and it is absolutely impossible for the observer to know on
which of these points her head may lay.
The course indicator light which in this position is obscured shows at once that
the vessel is heading between South and South West by South or within three
points to the left of his line of sight.
If the red light of the indicator diagram B Figure 3 were also visible she must
be heading between South West by South and West South West or more than
three and less than six points. If the white light of the course indicator was
showing in conjunction with the side light diagram B Figure 4 the vessel must be
beading more than six and less than 10 points to the left of his line of sight.
The same remarks apply in the case of the green light on the starboard side.
These lights would not interfere in any way with the present system of side
lights and might or might not be utilized by an observer who would have the side
lights to guide him exactly as at present,

page_text: They would when not visible make the present side lights seen singly serve as a
great danger signal and hence be of much greater significance than they are at
present by indicating at once to the observer that the vessels head was on the most
dangerous and advancing arcs (vide diagram B Figure 2) and less than three points
to the left or right of his line of sight which would be determined by the color of
the light.
They would when visible and in conjunction with the side light showing either
two red or two green lights become a little danger signal and indicate to the
observer at once that the vessels head was more than three and less than six points
to the left or right of his line of sight which would be determined by the color of
the lights.
They would when a side light and the white light of the course indicator were
visible in conjunction become a 'caution' signal and indicate to the observer that
the vessels head was more than six and less than ten points to the right or left as
the case might be of his line of sight.
Under ordinary circumstances (i.e. fairly clear weather) with this signal showing
there would not be any immediate necessity for action and time might be taken to
watch the strangers movements. Hence my reason for suggesting the name
'Caution' signal.
It would be impossible for a vessel whose side lights were visible to alter her
course more than three points on the Great Danger or little danger signal arcs and
more than four points on the caution signal are without it being indicated (ville
diagram C) and would enable an observer to form an opinion regarding any
manoeuvre the vessel might be making such as going about wearing round keeping
away or altering her course more than three points from that which she was
steering when she first sighted her lighter lights.
Their introduction could scarcely be the cause of any accident or confusion on
the part of the observer. Vessels approaching nearly end on would still show the
single red or green side light and this would be a signal of great danger to him.
Even supposing the vessel were not carrying the course indicator lights it would
make him more cautious and ready to act at once should it be his duty to give way
than he would at present.
Two red lights or two green lights seen so close together ought to confuse no one
even had he not heard of them. He would know that a red light meant that the
vessel was showing her port side to him and would act as under existing
circumstances.
I have used the terms less than three and less than six points as the course
indicator light would begin to show itself faintly about half a point before the
three point line on the great danger and the six point line on the little danger arcs
were opened. This I find would be necessary in order that they should shine
clearly and distinctly over their respective arcs.
It appears impracticable to cut off the light shown from a small lamp without
the use of very long screens placed outside it. This would not be desirable in a
lamp used as a vessels side light as it would make it cumbersome and easily
injured. The fact of the red or green light of the course indicator showing faintly
before its are opened is rather an advantage than an objection as it would inform
the observer the actual course within half a point the vessel was steering on that
line.
If the white and colored light of the course indicator were visible at the same
time it would then determine her actual course within one point of the six point
line (see Diagram A).
The course indicator lights will not interfere in any way with the present side
lights but act solely as a guide and help to commanders and officers of vessels as a
course indicator and to be used solely for that purpose.
The lights would probably assist Judges of Marine Courts in arriving at
their decisions in cases of collision that take place at night by enabling them to

page_text: determine more accurately from the evidence the course and manoeuvres of either
vessel prior to the accident.
The extra expense namely the cost of the lamps and placing them in position
would be very small.
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
The whole invention substantially as specified and illustrated in the accompanying
drawings.

page_text: Fig. 1.
Represents the ure of the "honzerv
to the left or right of the observe
line of night over which, a rassili
may move without any medication,
wonder the present system

page_text: wels head.
&W'S Wor
itserver's
White lisible
Trilerates that the vessel's hond lay
belive WSW&WNW or more than
6 & less than 10 privits to the left of
The observer's line of sight