Hoods rangefinder (instrument)

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Nellie
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Hoods rangefinder (instrument)

Post by Nellie »

I am very curious about the rangefinder on hood and how it worked compared to the king george v and Nelson class rangefinders, do anyone know the differences between them and if one of them was better than the other. I have seen a picture of hoods rangefinder and it looked like some kind of klockface with pointers you could move but i didn´t understand exactly how it worked. Can i read about it somewhere?
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Re: Hoods rangefinder (instrument)

Post by Tiornu »

A rangefinder is one component of a ship's fire-control system, but I don't think it's the item you have in mind. A rangefinder exaggerates a person's binocular vision--almost as though a person's two eyes were 15 feet apart, or even more. It looks like a horizonal bar that is fixed to a pivoting structure. In fact, a turret may have a very large rangefinder; this would look like a pair of "ears" sticking out the side of the turret near the back.
The purpose of this device, as its name says, is to determine the distance from the ship to the target. This information is then sent to the ship's gunnery computer system. In the US Navy, this system included a component called a rangekeeper. That may be what's mixing you up.
Can you find a copy of Warship 2002-2003? It has an article called "Admiralty Fire Control Tables" which I think is the subject you're looking for.
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Clocks...

Post by Bill Jurens »

You are probably referring to what was typically known as a 'range clock'.
These items, which varied somewhat in appearance from navy to navy and from time to time, had a large (usually) circular clock-like dial facing fore-and-aft, with hands that could be moved to indicate (via a variety of systems) the range to target. The clocks were big enough so that they could be read from other ships up and down the battle-line who might otherwise not be able to obtain a reliable range. According to some sources, by setting the hands in various ways, one could transmit other messages as well.

Range clocks seem to have died out by the mid 1930s or so, replaced by other means of communication.

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Post by Monitor »

Take a look at this page from the Hood website.

http://www.hmshood.com/ship/specificati ... ntrol.html

I hope it helps.
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Nellie
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Re: Hoods rangefinder (instrument)

Post by Nellie »

Tiornu wrote:A rangefinder is one component of a ship's fire-control system, but I don't think it's the item you have in mind. A rangefinder exaggerates a person's binocular vision--almost as though a person's two eyes were 15 feet apart, or even more. It looks like a horizonal bar that is fixed to a pivoting structure. In fact, a turret may have a very large rangefinder;
this would look like a pair of "ears" sticking out the side of the turret near the back.
The purpose of this device, as its name says, is to determine the distance from the ship to the target. This information is then sent to the ship's gunnery computer system. In the US Navy, this system included a component called a rangekeeper. That may be what's mixing you up.
Can you find a copy of Warship 2002-2003? It has an article called "Admiralty Fire Control Tables" which I think is the subject you're looking for.
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Nellie
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Post by Nellie »

I see what you mean now, i have painting of h.m.s Nelson at home and when i look closer i can se some kind of lins inside those boxes sitting at the turrets. Is it a zooming function on the rangefinder to decide the range then?
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Hood's range finder

Post by turlock »

There is a large, old, British range finder at Katoomba, N.S.W., Australia, in the Blue Mountains. The optics were messed up when I looked through it in '85, but it was of a size that could have come from a capital ship. A shame it had to sit out in the weather and get ruined.
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Post by tommy303 »

Nellie,

Rangefinders work on a principle of triangulation. The left prism is fixed at 90 degrees to the base of the rangefinder, while the right prism is movable so that when it is adjusted to intersect the line of sight of the left prism, a right triangle is formed, solving a trignometric formula and providing a solution. The operator sees the true image of the target, from the left prism and a ghost image from the right. By turning a hand wheel or knob, he adjustst the right prism until the two images are brought into coincidence, thus completing the triangle. When has done this, range can be read off a scale at the hand wheel.

tom

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