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Old 27-09-2015, 11:10   #16
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Re: What is a good steering compass?

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Originally Posted by alansmith View Post
Navigation is one of the most fascinating subjects there is. You should also educate yourself about magnetic deviation in your region.

China has already shown the international communities that it can destroy satellites in orbit. Do u have any idea how much I our military infrastructure depends on satellite gps info? If a war broke out do u think military commanders would leave that card untouched? I think map and compass work is one of the coolest mind stimulations there is in a boat. Don't miss the opportunity to improve your skills without gps... Use it as your backup plan. Just my way of thinking.

+1 About a year and a half ago, the British MOD put out an alert saying that due to military maneuvers, GPS may not be available or MAY PROVIDE FALSE LOCATIONS (emphasis mine). GPS may also be affected by solar storms. More likely, faulty wiring in the boat or GPS unit may affect the unit.
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Old 27-09-2015, 11:15   #17
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Re: What is a good steering compass?

For a 22ft cabin cruiser I would suggest purchasing an electronic compass, for a lot of reasons. To begin with, it will be more accurate as it is easier to calibrate than even the most expensive magnetic compass. It will be easier to read in rough conditions too when a traditional compass is bouncing all around.

On ebay and elsewhere, you can buy them for under 10 pounds if you are under a budget (and everyone is, just the number changes and not that I recommend purchasing the absolute cheapest thing possible). Anyway, I would get something there, and after calibrating it to your boat use it to calibrate your magnetic compass. You don't even need to fiddle with the magnetic compass, just make up a card:


Do this with your compass in its mount and the engine running. Just steer the magnetic course on the electronic compass and write in the box what the magnetic compass reads. You can also make up a second card taking the magnetic variation into account, so the card can tell you what compass course to take for a true heading. (there are other ways of doing it but since you are asking here you don't know them yet. When you do know them you won't necessarily need a second card but it can help for now and you will know when you do not need it any more).

Anyway, that is how I would approach your problem. To purchase a quality magnetic compass and have it professionally swung would cost more than purchasing a cheap electronic one AND paying to take a navigation class which actually might just cost less than the compass which is what I would recommend.
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Old 27-09-2015, 11:36   #18
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Re: What is a good steering compass?

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Originally Posted by MBWhite View Post
For a 22ft cabin cruiser I would suggest purchasing an electronic compass, for a lot of reasons. To begin with, it will be more accurate as it is easier to calibrate than even the most expensive magnetic compass. It will be easier to read in rough conditions too when a traditional compass is bouncing all around.

On ebay and elsewhere, you can buy them for under 10 pounds if you are under a budget (and everyone is, just the number changes and not that I recommend purchasing the absolute cheapest thing possible). Anyway, I would get something there, and after calibrating it to your boat use it to calibrate your magnetic compass. You don't even need to fiddle with the magnetic compass, just make up a card:


Do this with your compass in its mount and the engine running. Just steer the magnetic course on the electronic compass and write in the box what the magnetic compass reads. You can also make up a second card taking the magnetic variation into account, so the card can tell you what compass course to take for a true heading. (there are other ways of doing it but since you are asking here you don't know them yet. When you do know them you won't necessarily need a second card but it can help for now and you will know when you do not need it any more).

Anyway, that is how I would approach your problem. To purchase a quality magnetic compass and have it professionally swung would cost more than purchasing a cheap electronic one AND paying to take a navigation class which actually might just cost less than the compass which is what I would recommend.
Question? With a 22 ft. cabin cruiser how accurate is necessary? He is not likely to circumnavigate. Likely only needs to get to a sea buoy or range lights if that? A half assed descent magnetic compass will probably do him well. And magnetic deviation is probably not an issue? JMHO Sounds like making a mountain out of a mole hill.
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Old 27-09-2015, 11:55   #19
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Re: What is a good steering compass?

Here's ours. OK I'm just sharing because I think it's beautiful.

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Old 27-09-2015, 18:03   #20
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Re: What is a good steering compass?

steering a large ship holding course within half a degree is a job for an autopilot not a human. I don't know any sailors who would claim to be able to do it.
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Old 27-09-2015, 18:21   #21
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Re: What is a good steering compass?

Quote:
Originally Posted by alansmith View Post
Navigation is one of the most fascinating subjects there is. You should also educate yourself about magnetic deviation in your region.

China has already shown the international communities that it can destroy satellites in orbit. Do u have any idea how much I our military infrastructure depends on satellite gps info? If a war broke out do u think military commanders would leave that card untouched? I think map and compass work is one of the coolest mind stimulations there is in a boat. Don't miss the opportunity to improve your skills without gps... Use it as your backup plan. Just my way of thinking.
+1 About two and a half years ago the British MOD put out a notice that in one area GPS might not be available and MAY GIVE FALSE READINGS (emphasis mine) due to military exercises. Additionally, solar weather can affect GPS availability. On top of this, a more likely problem is that wiring and electronics may go bad. Think Murphy's Law; if it can go wrong it will (And usually at the worst possible time!).
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Old 27-09-2015, 18:37   #22
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Re: What is a good steering compass?

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steering a large ship holding course within half a degree is a job for an autopilot not a human. I don't know any sailors who would claim to be able to do it.
Actually us navy quartermasters have been doing it for close to a hundred years on all manor of ships from destroyer escorts ( now called fast frigates). To aircraft carriers
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Old 27-09-2015, 18:52   #23
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Re: What is a good steering compass?

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Question? With a 22 ft. cabin cruiser how accurate is necessary? He is not likely to circumnavigate. Likely only needs to get to a sea buoy or range lights if that? A half assed descent magnetic compass will probably do him well. And magnetic deviation is probably not an issue? JMHO Sounds like making a mountain out of a mole hill.
Voltaire quoted an Italian proverb when he said "Perfect is the enemy of the good." Put another way, a magnetic compass is likely good enough.
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Old 27-09-2015, 19:28   #24
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Re: What is a good steering compass?

Yes, the military has the ability to "dither" the GPS system in times of threat. I think if an ICBM with dozens of hydrogen bombs lit up san Francisco it would not matter if they had dithered the GPS or not.

There are many reasons to be good at compass work. Remember the line from the movie "White Squall" with Jeff Bridges...when the Cuban military boat commander smashes the ship compass...and Jeff B. tells the commander that a real sailor just has to look at the stars to know where he is...or something like that. There is a pride gained in skills learned is what I would say.

You will learn why you were a couple of miles off of your dead reckoning when your compass course was correct, wind steady, boat speed pretty well known...maybe you were traveling due north but a current was flowing across your course at some degree tangential to your course. Then when you travel that way again you will remember how much to offset that course heading to allow for the current.

Learning new skills is good for the brains development and I would say healthy for it to solve problems and make connections between hundreds of different little things. You will learn how to use map and compass, prevailing winds, currents, and obstacles to get where you want to go. How cool is that? Become your own master and depend on your own brain to solve issues involved with navigation. It is its own sweet reward. Any skipper here will tell you that there is deep satisfaction in knowing how to use map and compass without electronics. Sailors have been doing it for thousands of years. The south pacific sailors did it with stars and had no magnetic compasses. Only in the last several decades have sailors had the luxury of knowing where they are to a foot or less. Electronics are wonderful...but you better be good with map and compass if you are really planning serious blue water passages, caught in a fog bank, and you are trying to count the seconds between the blasts to know which buoy that represents on the charts...Map and compass work is just so much fun and deeply rewarding...
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Old 27-09-2015, 20:04   #25
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Re: What is a good steering compass?

For the OP... in the UK ( and most other places) I would be buying something from Plastimo Compasses - Compasses, Electronics & Navigation | Plastimo

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Old 27-09-2015, 20:23   #26
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Re: What is a good steering compass?

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Originally Posted by alansmith View Post
Navigation is one of the most fascinating subjects there is. You should also educate yourself about magnetic deviation in your region.

For example there is True North and Magnetic North. They are not the same. Depending on where you live you have to know what that deviation is for compass and map work. Read up or take a course it is really cool stuff.
Yes, good points.

Only thing is what you describe is actually called variation.

Yup, a little reading goes a long way.

The basic Chapmans and Duttons books are great for this material. Many books on compasses. Or find a reputable source on the internet. IU wouldn't be surprised if wikipedia has a good writeup.
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Old 27-09-2015, 21:34   #27
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Re: What is a good steering compass?

I believe the poster of #8 said he read his course if chart plotter or auto helm display. This would indicate he is using an electronic flux gate compass. Sudden (probably highly unlikely) gps outages will not affect this. Electronics failure on the boat is much more likely, but as he said he has back up with hand bearing compass.


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Old 28-09-2015, 00:52   #28
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Re: What is a good steering compass?

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For the OP... in the UK ( and most other places) I would be buying something from Plastimo Compasses - Compasses, Electronics & Navigation | Plastimo

Ping
Good on ya, Ping, ya answered the OP's question!

tat, he's given you good advice, and a link, too. Couldn't be much better than that!

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Old 28-09-2015, 02:57   #29
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Re: What is a good steering compass?

Thanks Ann , and also..

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.........the graduations were strange, and difficult to read. It made no sense to me at all. I want 0 degrees to 360 degrees, clear, and that it works well.

The one I bought had, if I remember, 60 divisions between, say, east and south. I would have thought it would be 90 divisions, or at least something divisible with 90.
Any small boat compass these days will most likely be marked every 5* ( about 'half a point' in old speak) so expect to find 72 'graduations' in total ....36 big ones...and 36 little ones...

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Old 28-09-2015, 03:10   #30
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Re: What is a good steering compass?

The Mil might look confusing but one mil is the angle subtended by one at a distance of one thousand- yards, metres or miles it does not matter.

So in gunnery terms quick and easy to make a corrections
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