Shuggy
Well-known member
I was given this last night. Any ideas what it is? The compass rose doesn’t spin so I wonder if it some kind of electric/fluxgate compass. Any ideas?
What is this?
- Thread starter Shuggy
- Start date
Bouba
Well-known member
It should polish up nicely
jamie N
Well-known member
I'd say that it was a repeater, such as seen on a bridge wing.
Bouba
Well-known member
What is an M Motor ?
Shuggy
Well-known member
I d-don’t know.
Shuggy
Well-known member
What does it get its signal from? A master compass?
Slowboat35
Well-known member
I think it's a pelorus display in some sort of non-operational frame, minus much of the 'doings' underneath.
Both inner and outer scales are mirrored showing they are intended to be read both directly and via a rotating prismatic viewer which is missing. The inner card is a simple compass display (likely a gyro synchro repeater) that rotates in the usual way while the very outer ring (ivory colour) is fixed relative to the ship's head, thgus it simultaneously gives both the magnetic bearing to an object as well as its relative bearing from the ship's head. Its function is a more complex version of a hand-bearing compass with a relative bearing feature added. Ship's heading is currently 188' m. Turning the mising sighting device to align on an object at say 100'm from the ship would indicate that it's relative bearing is 088' port of the bow, cue the report "Object in sight Sir, Red zero eight eight".
Quite what the ABCDEF means doubtless someone more familiar with such things will explain in due course.
Both inner and outer scales are mirrored showing they are intended to be read both directly and via a rotating prismatic viewer which is missing. The inner card is a simple compass display (likely a gyro synchro repeater) that rotates in the usual way while the very outer ring (ivory colour) is fixed relative to the ship's head, thgus it simultaneously gives both the magnetic bearing to an object as well as its relative bearing from the ship's head. Its function is a more complex version of a hand-bearing compass with a relative bearing feature added. Ship's heading is currently 188' m. Turning the mising sighting device to align on an object at say 100'm from the ship would indicate that it's relative bearing is 088' port of the bow, cue the report "Object in sight Sir, Red zero eight eight".
Quite what the ABCDEF means doubtless someone more familiar with such things will explain in due course.
Last edited:
Shuggy
Well-known member
Thanks - I had to google pelorus but I think you’re right. It has an MOD sticker on the bottom. I wonder where it has been? And what on earth do I do with it? It hasn’t passed the Mrs Shuggy test…
ProDave
Well-known member
The MOD sticker means modification record, nothing to do with M.O.D
I think it's the remains of a synchro resolver master / slave system Synchro - Wikipedia
When complete and working, the slave (indicator) follows the position of the master, which in this case would have been a master compass. but it looks like the works are missing from yours
I restored a similar thing for a friend, except it was a wind direction indicator but the same slave follows master principle applies.
I think it's the remains of a synchro resolver master / slave system Synchro - Wikipedia
When complete and working, the slave (indicator) follows the position of the master, which in this case would have been a master compass. but it looks like the works are missing from yours
I restored a similar thing for a friend, except it was a wind direction indicator but the same slave follows master principle applies.
Alex_Blackwood
Well-known member
It is a motor used in instruments (repeater) Years since I worked with them so hazy on detail. That looks, as already stated, Like a repeater, for a (Very) old Admiralty magnetic compass system. (WWII) vintage originally.
Bilgediver
Well-known member
I suspect it is an electric repeater where a signal from the main gyro compass drives a stepper motor in the repeater in possibly 1/2. degree Stepps. That is possibly a 3 or 4 pin connecter . There would be one on each bridge wing as well as a steering compass at the helm. Some times the steering compass was digital and above the forward bridge windows .
Slowboat35
Well-known member
As I surmised last night, and here is a link to the user manual of a modern equivalent that explains how the various scales are used.
Still no idea about the ABCDEF though.
Pages 29 and 35 are where you'll find the useful info.
Chapter 2: Operation; Readout Elements, Indicators And Controls - Sperry Marine 5016-CA Operation, Installaion And Service Manual [Page 29]
Obviously the OP's instrument does not have the expanded 10degree scale.
Still no idea about the ABCDEF though.
Pages 29 and 35 are where you'll find the useful info.
Chapter 2: Operation; Readout Elements, Indicators And Controls - Sperry Marine 5016-CA Operation, Installaion And Service Manual [Page 29]
Obviously the OP's instrument does not have the expanded 10degree scale.
Pump-Out
Active member
Perhaps for reporting aircraft?
If aircraft are transiting quickly, it would be easier to report by compass sector, rather than a clear bearing.
Bouba
Well-known member
It’s in a polished wood bezel......so....probably not an aircraft instrument
Pump-Out
Active member
Not what I said.
If we accept the opinions up thread that it's from a large ship, used to report contacts, then reports of aircraft contacts might also be required.
Bouba
Well-known member
I know that...but I was leading up to it might be from a dashboard of a Jag
sarabande
Well-known member
Hmm, I tried a close-up of the coronet (?) below where the cardinal mark for North should be. Does it look like an Admiralty one, or slightlu foreign ?
The use of sextants (A to F) seems to indicate a lack of precision which might mean a 'general' direction ("Submarine at D") was acceptable. It puts me in mind of one of the Chernikeefe systems on sweepers in 1960s; they used to tick tick tick as the ship's head tracked round the horizon, and sometimes the ship swung faster than the gyro, which caused the helmsman some excitement. I think the display had some letters on it as well as degrees.
The use of sextants (A to F) seems to indicate a lack of precision which might mean a 'general' direction ("Submarine at D") was acceptable. It puts me in mind of one of the Chernikeefe systems on sweepers in 1960s; they used to tick tick tick as the ship's head tracked round the horizon, and sometimes the ship swung faster than the gyro, which caused the helmsman some excitement. I think the display had some letters on it as well as degrees.
Last edited:
Seastoke
Well-known member
Mr angry.
Shuggy
Well-known member
Thanks everyone - that’s been an informative thread! We will polish it up and decide what to do with it.
Slowboat35
Well-known member
Aircraft?
The pic below, and hundreds like it on t'internet shows the sighting system to be verical slots which is necessary to cope with sighting from a pitching and rolling vessel. Thus to some extent it would allow a degree of vertical freedom regarding the target - useful enough perhaps for an approaching lowish level maritime patrol aircraft though obviously unsuited for high-level/high vertical angle attacks.
So it would have some useful but limited function in that scenario but I'd suggest -nay - state categorically this is not the OP's device's intended function.. I don't doubt that specialised high-level aircraft-reoprting sighting devices exist/ed but this is not one of them, just a pretty standard but very accurate chart-and-pencil maritime nav-aid like a slightly advanced handbearing compas.
I think you'll find the almost exact equivalent on all His Majesty's ships today. A pelorus is an essential non-technological tool for super accurate dead-beat positioning of a ship in close quarters.
Nonetheless the OP's heirloom is a rather wonderful piece of maritine history and with some cleaning up and restoration would make a handsome, notable and enviable conversation piece on any mantlepiece.
If he doesn't want it I certainly have space for it on mine!
As I'm intrigued about the markings ABCDEF I've taken the liberty of asking about them on the ship's forum whre there might be wider/older knowlege.
I hope that's OK...
Curious Instrument Markings
The pic below, and hundreds like it on t'internet shows the sighting system to be verical slots which is necessary to cope with sighting from a pitching and rolling vessel. Thus to some extent it would allow a degree of vertical freedom regarding the target - useful enough perhaps for an approaching lowish level maritime patrol aircraft though obviously unsuited for high-level/high vertical angle attacks.
So it would have some useful but limited function in that scenario but I'd suggest -nay - state categorically this is not the OP's device's intended function.. I don't doubt that specialised high-level aircraft-reoprting sighting devices exist/ed but this is not one of them, just a pretty standard but very accurate chart-and-pencil maritime nav-aid like a slightly advanced handbearing compas.
I think you'll find the almost exact equivalent on all His Majesty's ships today. A pelorus is an essential non-technological tool for super accurate dead-beat positioning of a ship in close quarters.
Nonetheless the OP's heirloom is a rather wonderful piece of maritine history and with some cleaning up and restoration would make a handsome, notable and enviable conversation piece on any mantlepiece.
If he doesn't want it I certainly have space for it on mine!
As I'm intrigued about the markings ABCDEF I've taken the liberty of asking about them on the ship's forum whre there might be wider/older knowlege.
I hope that's OK...
Curious Instrument Markings
Last edited:
Other threads that may be of interest
