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Old 09-03-2014, 03:16   #16
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Re: Is a compass your primary navigation instrument or back up?

Ok,

Try a sail from Sydney,BC to Victoria,BC.

By route of Enterprise Channel, and then inside Trial Island.

You can start on both ends in clear, and find yourself in peaSoup.

Now tell me that real time isn't involved.

I would never sail this route, without a proper swung floating card.

Nothing Digital could show me the way, in real time.

It's a course I make 2wice a year, for the last 16.

Lloyd

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Originally Posted by noelex 77 View Post
All instruments have some error and lag including the traditional analogue magnetic compass. Perhaps one day they will have zero mass compass cards and zero friction bearings, but not in my lifetime.

I am not sure this has such a great influence on our relatively slow turning cruising boats, but a GPS compass, or even a good gyrostabilised compass is superior.

My own boat has a simple gyrostabilised fluxgate compass which is probably on about par with the conventional magnetic compass. The biggest difference is the human interface. For autopilot steering the digital display is superior, but hand steering the analogue display is better (at least for me). More modern instrument systems can present the electronic compass in an analogue format when desired.
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Old 09-03-2014, 03:43   #17
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Re: Is a compass your primary navigation instrument or back up?

Given the cash, I would like a GPS Compass (in addition to the magnetic compass)

As an aside, I can give a practical comparison on the compasses, installed on a large tug boat, just for interest.

Following are installed
2 x Gyro Compasses
1 x GPS Compass
1 x Magnetic Compass in binnacle

The gyro's may have a small fixed error, usually no more than a degree and this can be removed via the electronics, or just allowed for.
They also suffer from a lag after a large course alteration, but nothing too much.
Big disadvantage is the initial cost, and then the maintenance costs. The supporting fluid and pump needs changing out each year, and the sphere will last about 5 years before the bearings start to give way. Replacement of the sphere is about $5,000.

GPS Compass, relatively low cost installation, any errors due to siting can be easily removed by the software, and so far, no maintenance costs.

Disadvantage of the above is that they both require power, but the GPS compass is not very power hungry

The Magnetic Compass, suffers from the vagaries of deviation and to a lesser extent, variation. The heeling error magnets need to be adjusted with change of latitude.
Also suffers from a lag when changing course, and if a course has been held for some time, it takes time for the compass to settle after a course change

My favourite compass, easy, thats the magnetic compass. Its the only one I can really get to play with. There is a tremendous sense of satisfaction in swinging the compass, then properly setting the correction magnets, Flinders Bar, and "Kelvins Balls". If done properly, deviation can be reduced to less than a degree on all headings and at all latitudes (excluding close to the magnetic poles)
The only subsequent correction is that to the heeling error magnets, but thats pretty easy, and takes a few minutes.
Big advantage, no power needed.

For every day use at work, its the gyro compasses that get used.
On the sail boat, its the flux compass with the AP, and the magnetic compass when hand steering
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Old 09-03-2014, 04:00   #18
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Re: Is a compass your primary navigation instrument or back up?

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Originally Posted by FlyingCloud1937 View Post
I would never sail this route, without a proper swung floating card.
On that we are in agreement. A simple magnetic compass requires no power and its hard to imagine any cruising boat would be properly equipped without at least one.

I would also give a push for more use of the Hand bearing compass. Although my preferred model is shock, horror, an electronic fluxgate model. (The Autohelm HB compass)
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Old 09-03-2014, 04:03   #19
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Re: Is a compass your primary navigation instrument or back up?

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Originally Posted by nigel1 View Post
The only subsequent correction is that to the heeling error magnets, but thats pretty easy, and takes a few minutes.
If you ever get the chance adjust your compass when on the magnetic equator you shouldn't have to bother with any of that again.
Did it once 42 years ago ( back when I was bright eyed and bushy tailed) in the phillipines , worked a treat.
Ship was running Taiwan/all ports/'Straya and hadn't had the compass adjusted properly since she was built in Scotland.
I always enjoyed compass work, owed it to the bloke taking us for compasswork in London around that time... top bloke.
Don't remember his name or exactly what I did but typically at building they stick in way too much soft iron in front of the compass ie they give her too much Flinder's bar...
Not much relevance to this thread but there you go....
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Old 09-03-2014, 04:07   #20
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Re: Is a compass your primary navigation instrument or back up?

Back on topic... I don't use the magnetic compass much ... I tend to just point in the general direction of where I want to go... but when you want it you wouldn't want to be without it.... try getting your crew to hand steer in very light airs in the middle of a moonless night without one and with only an electronic 'çompass'' to work with....
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Old 09-03-2014, 07:02   #21
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Re: Is a compass your primary navigation instrument or back up?

I must be the odd duck! I love to hand steer the boat and I sail by the ticks after trimming for the course. I watch the compass to pick up the wind shifts and refer to the gps and chartplotter for reference as to how we are doing on the course. Of course my electronics are very basic and autopilot is used mostly for motoring.
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Old 09-03-2014, 07:14   #22
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Re: Is a compass your primary navigation instrument or back up?

I grew up in the 1960's and 70's on wooden boats with a magnetic compass and charts-and an extremely useful device not mentioned or appreciated--the binocular (not binoculars). Sure I've used autopilots, GPS, chartplotters, radar and they are terrific but I am concerned that some sailors overly rely on electronics and may not even be familiar or comfortable with the good old compass--friend to the navigator since human history began. But, I think that on an ocean voyage, many who get overly comfortable with electronics may not keep a written log or keep a dr plot and nothing was said about that above. Even a noonsight with a sextant can be helpful and confirm--and it's a good thing to practice. I am certainly no expert compared to the more experienced bluewater navigators or ocean passage makers out there--and there are many--but the old and the new are both important and sometimes the old way may be the only way when all else fails. Most of us have enough time at sea to use both the old and new so why not? Thank you.
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Old 09-03-2014, 07:28   #23
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Re: Is a compass your primary navigation instrument or back up?

in the last few years i have delivered a few steel vessels without workable compasses,had to rely on wind direction and wave direction to keep the boat on coarse!

that is,untill i could get the auto pilot going again,and the gps track to catch up on the plotter!
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Old 09-03-2014, 07:33   #24
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Re: Is a compass your primary navigation instrument or back up?

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Originally Posted by Paul Annapolis View Post
I grew up in the 1960's and 70's on wooden boats with a magnetic compass and charts-and an extremely useful device not mentioned or appreciated--the binocular (not binoculars). Sure I've used autopilots, GPS, chartplotters, radar and they are terrific but I am concerned that some sailors overly rely on electronics and may not even be familiar or comfortable with the good old compass--friend to the navigator since human history began. But, I think that on an ocean voyage, many who get overly comfortable with electronics may not keep a written log or keep a dr plot and nothing was said about that above. Even a noonsight with a sextant can be helpful and confirm--and it's a good thing to practice. I am certainly no expert compared to the more experienced bluewater navigators or ocean passage makers out there--and there are many--but the old and the new are both important and sometimes the old way may be the only way when all else fails. Most of us have enough time at sea to use both the old and new so why not? Thank you.
Good points Paul and like you I started learning how to sail in the 70's. We never stop learning.
In the days prior to all this electrickery stuff I spent literally hours steering by compass, taking cocked hats, putting everything in logs and on charts. The pencil, dividers and compass ruled.
Now I have the gizmos I use them all the time and hardly look at the compass from year to year. I do practice from time to time just to remind myself but I prefer to relax, use the auto pilot and sail by the wind.
All the other stuff is important I agree but tend to think for me they have been delegated to a back up rather than the primary means of steering/ navigation.
Nowadays we have GPS in everything including phones, I pads and cameras besides a back up GPS, a spare computer with it in (long battery life)
Yes one day the electricity mail fail but all my back ups. If they all do then there is the compass as my weapon of last resort.
It is not right for everyone but works for me.
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Old 09-03-2014, 12:38   #25
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Re: Is a compass your primary navigation instrument or back up?

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Originally Posted by Nostrodamus View Post
There has been another thread running about this in the UK and I just though I would put a similar question on here and get all the flack again.

I have said that with the type of sailing I do my primary means of navigation is by electronic instruments.

I helm the boat as little as possible preferring to use the auto pilot which is most often set to sail by the wind.

I cannot remember the last time I looked at the ships compass let alone sailed by it.

My view is that it has been demoted from the primary navigational instrument to a back up should all go wrong.

I seem to be pretty much alone in my view as most in the UK said that they always use their compass to sail by, especially when crossing several tides.

I still stand by my assertion that for me and the type of sailing I do a electronics are better and the compass is just a backup very much like my lead line to the depth sounder.

What do you think?
I'm from the UK too, but I'm with you. Well, sort of. When crossing varied currents my favourite mode on my Garmin Chartplotter is the compass with the arrow inside which points to your destination waypoint. The compass lines up with the direction in which you are travelling over the ground and the arrow in effect shows the amount of drift due to current. (The compass shows where you are going and the arrow shows where you want to go).

Unfortunately it doesn't hook up to the autopilot so requires manual helming, but if you keep the arrow and compass direction lined up and adjust your heading whenever the current changes you are always taking the shortest course to your destination. The nearest thing to a straight line.
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Old 09-03-2014, 13:29   #26
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Re: Is a compass your primary navigation instrument or back up?

I mostly use my electronic stuff over my dinosaur technology compass. I keep that low accuracy, low readability, but highly dependable compass around as a back-up.
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Old 09-03-2014, 13:59   #27
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Re: Is a compass your primary navigation instrument or back up?

We use our GPS Chart-plotter with the autopilot for cruising. We use the compass mostly for identifying sightings along the way. For example, one of us might spot a big fish, boat, structure, or hazard in the distance. We would use the compass to show the other where it is.
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Old 09-03-2014, 15:02   #28
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Re: Is a compass your primary navigation instrument or back up?

We run auto helm a lot but we keep a compass course at hand. Auto does go nuts or get overpowered from time to time so the binnacle compass is valuable to us. I particularly like the lighted compass at night as an instant sanity check.

In the olden days, there was often a device on near the compass with the desired steer-to course noted. Helpful to anyone coming on watch. This was a drum with three wheels & digits that could be arranged to display the heading. Another version had 'dice' that could be flipped to display the course. I'd like to find one but, alas, it has no wires so nobody wants to make or buy them.
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Old 09-03-2014, 15:32   #29
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Re: Is a compass your primary navigation instrument or back up?

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Originally Posted by noelex 77 View Post
On that we are in agreement. A simple magnetic compass requires no power and its hard to imagine any cruising boat would be properly equipped without at least one.

I would also give a push for more use of the Hand bearing compass. Although my preferred model is shock, horror, an electronic fluxgate model. (The Autohelm HB compass)
I love everything about mine except the accuracy (as gauged by repeatability, even under ideal circumstances, ie on land)

I've heard and seen adverse comments about the accuracy from a couple of others, so I assumed there was nothing wrong with mine.

Does yours check out, N77, and if so, what sort of repeatability can you manage?
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Old 09-03-2014, 15:50   #30
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Re: Is a compass your primary navigation instrument or back up?

Depends on the compass.

Careful on this one - its like getting your tongue stuck on the pump handle.

http://towndock.net/img/6812.jpg
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