Compass?

[forestacademy]

Originally Posted by Old smart

I'm retired now, but yes I have, including an old K&E vernier sextant similar to the pictured. I haven't used my present Zeis micrometer drum sextant since retiring.

Hu Hu

You said Sextant

[Old smart]

Yup, sextant as in 1/6th of a circle (the graduated arc). Due to the nature of the light path, 60º of arc accomodates 120º of measurement, primarily vertical, but sometimes horizontal. At one time there were marine "octants," and there still are "quintants" and "quadrants" (special types of survey instruments used for horizontal angles and arcs of 140º or 180º).

[SmartChip]

Craven, My first thought for a really excellent accessory would be a nice, top of the line GPS unit. They will get you anywhere in the U.S. and they have a built in compass. Pick a brand, compare the specs and features you like and buy-buy-buy. Cheerz, SmartChip

[sunnyokanagan]

Originally Posted by jwight

Very old school and under 10 bucks: Amazon.com: Bell 24000-1 Traveler Compass: Automotive

Tried it. Three different makes at low/med/high price points. Magnetic compasses just do not work in my smart car!

[jediknight36]

Originally Posted by jetfuel

well...let me get you in a little secret...I believe Old smart(moderator) still uses one of this..




jetfuel

Uses? More like invented! When he talks about his days in the Navy, he is referring to the ROYAL Navy!

Got any propwash?

[jediknight36]

Originally Posted by forestacademy

Hu Hu

You said Sextant

I think I am the only other one young enough to get that.

[jediknight36]

Originally Posted by sunnyokanagan

Tried it. Three different makes at low/med/high price points. Magnetic compasses just do not work in my smart car!

Stupid question, but why?

[jwight]

Originally Posted by jediknight36

Stupid question, but why?

+1 Would like to know also.

[Old smart]

Originally Posted by jediknight36

Stupid question, but why?

Compensating (correcting) a magnetic compass when it is surrounded by iron/steel is a very complex endevor, and only accomplished by experts, and if the compass has a number of adjustable error compensators. Some advertisers tout that the compass has a "variation" adjustment - fine if the compass is well away from any magnetic influence and not installed in an automobile - a simple and known offset. It only compensates for the fact that the earth's north magnetic pole is a considerable distance from the geographic pole, now in far North-Central Canada (and the magnetic poles slowly wander over the eons).

The really tough nut is another form of error called "deviation," and in three forms - permanent, quadrantal and vertical. It is the influence of close-by iron or steel, and in a smart, that stuff is very close-by. No diddley eBay compass will have the many compensators needed, nor the buyer the knowledge to adjust them if they were there.

N.B. When a ship's engineering plant fails, as they sometimes do, and all the electronics stop and their internal batteries also soon fail, what do you do? You still break out a sextant and hope to hell that it is collimated and in good condition and your vessel's chronometers are working and their error rates recorded daily. No Mate or Master ever trusts the "ship's sextant;" that is why they carry their own

[John_H]

So are we hearing that the only way to have a compass on a smart (electronic or otherwise) is to extend it on a long boom away from the metal tridion cage of the Smart?