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What Is This?

Discussion in 'Technical Discussion' started by discokachina, Sep 10, 2012.

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  1. discokachina

    discokachina Senior Member

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    What is this?

    whaisit.JPG

    I think I have seen these on a number of bridges but do not know what it is or does?
  2. K1W1

    K1W1 Senior Member

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    Hi,

    It looks like a magnetic compass. This is used to show which direction you are heading.
  3. discokachina

    discokachina Senior Member

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    Thanks K1W1, I thought I could almost make out a compass wheel but could not figure out what the optics do and how you would easily read it unless there is a gauge on the helm?

    Why is it located where it is on the ceiling?

    Is the ceiling mount any different than these

    compass.JPG

    I am familiar with?
  4. K1W1

    K1W1 Senior Member

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    Hi,

    It looks like it uses a mirror to show the heading the right way up.

    They are also sometimes used as the autopilot compass.

    One system I sailed with was a Segatron unit - not sure they are still going but it was reliable and simple to use.

    They are mounted where the person who runs the boat wants in most cases at build/install
  5. discokachina

    discokachina Senior Member

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    Thanks K1W1 for heading me in the right direction! I found that style is also known as a "telltale" compass and seems to be hard to find.

    Here is a picture of one from Cassens & Plath, looks pretty fancy to me!

    cassenspklath.JPG

    I guess you can tell that I have not been on many bridges of larger yachts. :(
  6. AlfredZ

    AlfredZ Senior Member

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    Hi,

    Saw it once only on a tug boat, the optical light was black and the degrees were florescent so at night is "greenish" like a radar screen, nice and soft on the eye.
  7. discokachina

    discokachina Senior Member

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    Just for fun I thought I would find out how much these babies cost, not for the faint hearted!

    Cassens & Plath OVERHEAD-COMPASS/180
    with steering compass Type/11 (180 card dia.),
    mirror and lens, illumination 24vdc, longitudinal gimbaled
    complete with
    1x compass mounting brackets, pair
    1x B+C corrector device, separate
    1x D corrector (Mu-Metal induction sheets) with centre pivot
    1x Heeling corrector, separate
    1x iIIumination dimmer with box 24vdc, 5VA for flat top compass

    PRICE: SGD 3,990.00 per set (DDP Singapore)

    I guess this is a case of the right tool for the right job!!!
  8. dennismc

    dennismc Senior Member

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    Actually I am looking for something similar, when my Yacht was built the owner was fairly tall and the dash mounted 8 " compass was a little too far forward for me to read in comfort from the helm seat, what I need is an overhead mirror system that I can attach to the underside of the overhead instrument rack that will let me read the compass in comfort, the small prism at the front of the compass was lost quite a while ago, any ideas or clues would be much appreciated.
  9. Beau

    Beau Senior Member

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    K1W1

    What need in the market does this type of compass fill over the standard flush/ surface mounted compass?
  10. sunchaserv

    sunchaserv Member

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    Lest I start a thread creep, but in this age of plotters and related electronic data, how many really use their compass?
  11. dennismc

    dennismc Senior Member

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    When I made a trip down the West coast to Mexico, my chartnav system became a bit unstable, I wanted to steer by compass course until everything stabilized, was a bit of an aggravation due to difficult reading as previous post.
    Backup is critical when in offshore waters.
  12. Fishtigua

    Fishtigua Senior Member

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    Before the days of GPS and chartplotters, we used to use No.1 eyeball navigation, a chart and a compass. In the South Pacific you may only get one fix in 14 hours from the SatNav.

    Sailing through the Torres Straits in Northern Australia at night, in a 220 footer at 12 knots, was not for the fainthearted. You needed every piece of equipment available. Those compasses are there for a very good reason.

    Attached Files:

  13. K1W1

    K1W1 Senior Member

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    Hi,

    The vessel I am on currently has the dash filled with all things electronic.

    We have a dual Gyro Compass setup.

    The Magnetic Compass is mounted in the overhead and has a mirror to make the numbers look the right way for the helmsman or woman.

    There is a repeater of this at the Emergency Steering Station should the brown stuff have really hit the fan.

    Fish, Don't forget about a well known Englishman who got from the Pacific to Singapore 200 some years ago in an open boat with very few if any navigational aids or instruments.
  14. Fishtigua

    Fishtigua Senior Member

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    There was another one who went from Antarctica to South Georgia with very little too.

    Thinking about it, most of the boats I've worked on have had overhead compasses mounted well away from electronics and other interferences to the magnets.

    When this thread came up, I honestly thought it was a joke one.

    Sorry. :(
  15. discokachina

    discokachina Senior Member

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    Try contacting these folks Alphatron Marine BV - Overhead compass