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Old 10-03-2014, 11:18   #46
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Re: Is a compass your primary navigation instrument or back up?

I'm usually looking for something to keep me occupied while zipping along at 6mph, so the old fashioned compass and paper chart is often used for a check of landmarks and depths... Of course I could look at OpenCPN and save the mental exercise.
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Old 10-03-2014, 12:41   #47
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Re: Is a compass your primary navigation instrument or back up?

I would say the depth sounder is my primary watch keeping tool in concert with the assumed charted positions that the various nav. instruments offer.

The standard compass is for me now mostly relegated to a ‘piloting tool” as I get better range and bearing fixes with my radar if coasting.

However, as someone said, at 6 knots, there is lots of time to verify your basic sensing equipment.

So whenever sailing in line with natural transits I regularly monitor and log the standard compass errors, so that if all else fails, I can more confidently DR or EP with it.

Of course like everyone else. I am easily sucked into the comfort zone of GPS…. But I will never let go of my navigating skills and depend on GPS always being there.
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Old 10-03-2014, 13:50   #48
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Re: Is a compass your primary navigation instrument or back up?

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Originally Posted by Jammer Six View Post
Puget Sound, charter fleet.

Primary is iNavX and SeaIQ on an iPad mini, followed by whatever plotter the boat I happen to be on has.

On a typical cruise, there are four or five people on board, three of whom will have an iPad and all of whom will have a phone. So there's usually at least six independent GPS systems running besides whatever electronics the boat has.

When we take shots to practice manual fixes, we use Steiners, not the compass. When we practice paper, we go from paper to Steiners and Steiners to paper.

I've never used the boat's compass for anything, and I'm not sure what I'd use it for in Puget Sound. It's too easy to look around and see where you are. In fog, there's no possible way I'd trust the compass over the electronics.

Fog is not the time to learn new skills, fog is the time to go with what you know. So in fog, I use what I use the most-- the iPad.

In Puget Sound, we don't really worry about the rhumb line, we set the destination according to the current, and then sail to it according to the wind.
I had a recent learning experience in extremely heavy fog while heading through a narrow passage. Although our Navigation was by GPS chartplotter on the binnacle, we quickly found that our Steering had to be by the compass. The COG indicator on the screen lagged too much and we were literally turning circles (we were under power in no wind) until we figured out we had to steer by the compass. It was the only thing that gave us adequate situational awareness to travel in a straight line.

Of course, using the autopilot would have done the same, but we were in tight quarters and hugging the shoreline, so monkeying with the AP would have made things worse, not better.
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Old 10-03-2014, 13:58   #49
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Re: Is a compass your primary navigation instrument or back up?

Here is a different situation in which we could not use a compass to steer by but the chart plotter was really useful.
If you could think of a better or easier way of doing it I would be happy to listen and learn.

The blog (quiet short) is here with photos of the water we went through.

Cygnus III | Sailing Cygnus into the cauldron. The Strait of Messina.
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Old 10-03-2014, 14:12   #50
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Re: Is a compass your primary navigation instrument or back up?

Depends which one of us has the watch! For me:

Long cruise:
We sail using DR - Compass, charts, decent timepiece, Steiner binocular.
Steering is done with a Monitor wind vane (non-electric).
Keep a "Running Log" book for tracking position, course/speed/etc.

We use GPS to compare and correct our DR. Extra columns in running log.
Pencil position notations entered on the charts reflect our GPS datum.

Over the years we've become better at DR and the GPS correction correspondingly smaller. "Better" not exactly meaning "really good"!

Coastal cruising:
Same as above but add radar as desired/dictated (fog, dense traffic, etc.). With our older model amp-hungry radar, that usually means firing up the Iron Horse to spin the alternator.

But if my wife has the con? Well, then things differ. It's why I added a 3-metre extension to the power cable for her hand-held Garmin GPS. She's younger. Kids these days - what can ya' do?

James
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Old 10-03-2014, 14:27   #51
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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
Jim I think your point that there needs to be a reasonable and variable current (relative to boat speed) is well made. I agree on many passages steering the rhumb line is perfectly satisfactory, but there are other times when it can make passage times much longer.

These passages are not confined to English Channel. Sailing around the opposite side of world, (in Queensland waters) in my early days, showed that passages could be very long and uncomfortable if you don't get this right. Admittedly I was cruising in small yacht which exacerbates the differences.

I also disagree that you necessarily need very predicable tides. A simple example is sailing across across a tidal stream that you know is going to strengthen. Rather than sailing the rhumb line an initial offset upstream is simple to incorporate and need not necessarily be precise to provide worthwhile gains. I am sure you instinctively do these sort of things, but many inexperienced navigators do not and even worse think the Rhumb line course is optimum so never even attempt to make these corrections.
Noelex, I'm sure that there are places where ad hoc course corrections can improve passage times, and I agree that one tends to do that without much data. On the other hand, using the YRA approved CTS calculations (or the improved versions posted in the linked thread) can lead one to be sailing far from the rhumb line. This can lead to encountering unexpected hazards unless one has good data enabling one to pre-calculate one's actual course over the bottom (a non-trivial practice IME).

Just curious: where in sunny Qld did you find these conditions? I haven't found many places that compare at all with the EC in terms of crossing strong tidal flows for many miles. Plenty of places where avoiding wind against tide situations can increase both speed and comfort (especially in a small and slow boat) such as the Whitsunday Channel. For me, the big tidal issues in Oz have been regarding bar crossings and voyages up and down rivers... fortunately, here in Oz pretty good tidal info is available, and these passages don't really tax things, for they are up and down rather than across the flows.

Cheers,

Jim
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Old 10-03-2014, 15:21   #52
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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
Here is a different situation in which we could not use a compass to steer by but the chart plotter was really useful.
If you could think of a better or easier way of doing it I would be happy to listen and learn.

The blog (quiet short) is here with photos of the water we went through.

Cygnus III | Sailing Cygnus into the cauldron. The Strait of Messina.

If you have a good radar onboard, parallel indexing is a really useful means of piloting in these situations.
Never been through the straits on a sail boat, but plenty of times when working on cargo ships. Always used PI to navigate through, (no GPS onboard either)
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Old 10-03-2014, 15:35   #53
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Re: Is a compass your primary navigation instrument or back up?

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If you have a good radar onboard, parallel indexing is a really useful means of piloting in these situations.
Never been through the straits on a sail boat, but plenty of times when working on cargo ships. Always used PI to navigate through, (no GPS onboard either)
See, I am learning. I know I have no idea what parallel indexing is.
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Old 10-03-2014, 16:16   #54
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Re: Is a compass your primary navigation instrument or back up?

Parallel indexing is a technique defined by William Burger in the 1957 book The Radar Observer's Handbook. This technique involves creating a line on the screen that is parallel to the ship's course, but offset to the left or right by some distance. This parallel line allows the navigator to maintain a given distance away from hazards.

Now I know.
Ok in a big ship but quiet difficult in those waters in a smaller yacht when you are also trying to avoid ferries bent on killing you and the current is sending you all over.

Intrestingly I looked at some time lapse video of a big ship going down there and it was quiet apparent they were being effected and snaking quiet a bit.
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Old 10-03-2014, 17:07   #55
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Re: Is a compass your primary navigation instrument or back up?

Quote:
Originally Posted by Jim Cate View Post
Just curious: where in sunny Qld did you find these conditions?
Crossing the whisunday passage you have already mentioned, but the currents further south are stronger.

Currents do not necessarily have to very strong. They just have to significant (and variable) in relation to boat speed.
Sailing to outer reef was a good example of this. The best times to visit were when the wind was going to be very light for several days and in small yacht low average speeds in the 2-3 knot (or less) range make even small current significant. There is always some time pressure as the reefs cannot be safely negotiated late in the day so efficient navigation is important.
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Old 10-03-2014, 17:25   #56
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Re: Is a compass your primary navigation instrument or back up?

Quote:
Originally Posted by Nostrodamus View Post
Parallel indexing is a technique defined by William Burger in the 1957 book The Radar Observer's Handbook. This technique involves creating a line on the screen that is parallel to the ship's course, but offset to the left or right by some distance. This parallel line allows the navigator to maintain a given distance away from hazards.

Now I know.
Ok in a big ship but quiet difficult in those waters in a smaller yacht when you are also trying to avoid ferries bent on killing you and the current is sending you all over.

.
Not difficult at all, I do it on my little boat as well as my big ship.....
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Old 10-03-2014, 17:32   #57
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Re: Is a compass your primary navigation instrument or back up?

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If you have a good radar onboard, parallel indexing is a really useful means of piloting in these situations.
Never been through the straits on a sail boat, but plenty of times when working on cargo ships. Always used PI to navigate through, (no GPS onboard either)
+1
Actually PI still remains my favorite standing order on larger yachts and every deck officer who has ever worked for me come to embrace it and have told me they now incorporate it into their own command as a North up navigational tool.

One great benefit specific to yachts sightseeing coastal areas, is that it allows you to prepare and preset your course and CPA off of the shoreline, based on studying soundings and off lying dangers.

You want to get close enough to make it interesting, but not have a Costa Concordia event.

PI preparation disciplines you to stay in that safe zone, even if the GPS lags or is compromised for some reason.

I still use it on StarGazer, day and night and can relax when not on watch.
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Old 10-03-2014, 18:59   #58
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Re: Is a compass your primary navigation instrument or back up?

If you don't have a chart plotter in the cockpit, then old fashioned compass it is. We navigate with OpenCPN on a laptop down in the nav station. Being a sail boat, it moves slowly, so an occasional duck down below to check position and COG is all thats needed. Compare with the compass course its obvious how much leeway there is and what correction is needed. With analogue wind vane, steering is not straight anyway. Near enough is good enough when out in the open sea.
Looks handy having a great chart plotter in your face all the time, but as I said, we're moving at walking pace! Compass does fine.
Don't do radar.
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Old 10-03-2014, 21:02   #59
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Re: Is a Compass your Primary Navigation Instrument or Back Up?

In keeping with the entreaties of the Punctuation Police and Anti-Acronym Activists on other threads, I am empowered to ask nicely, if it's not a bother:

Is your "Don't do radar" a personal disclosure, or something more along the lines of "Kid's, Don't Do Radar, OK?"

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Old 10-03-2014, 21:29   #60
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Re: Is a Compass your Primary Navigation Instrument or Back Up?

Interesting thread. Thanks for the headsup on PI, Nigel; I'd never heard of it neither, but it makes immediate intuitive sense, and it seems a nice simple -- but robust -- concept in terms of what it delivers.

As for the OP's question: I have personal misgivings about reliance on intelligent tech on my own boat.

I've spent much of my life as a baby sitter, or critical care provider, or agony aunt, for technology items and IT issues, and was until recently a chronic early adopter in land-based contexts. I have lost count of the number of CFOs (sorry, Chief Financial Officers) with whom that has caused me to cross swords.

But I like sailing for how it presents me with other, less contrived challenges.
(by which I mean, challenges which were not "written" by other humans)

Challenges which (unlike the IT challenges) are still as satisfyingly responsive to the same all-purpose problem-solving skillset as I found them to be decades ago, when I first struggled with them.

I'm increasingly dis-infatuated with the sort of rote-learning involved in keeping pace with an upgrade cycle measured in months rather than lifetimes.

I have a feeling that the capacity for an individual brain for rote-learned, time-stamped facts, such as (trivial example) how to configure an Ethernet crossover cable, is finite,

and I'm no longer interested in pushing up against that ceiling with facts which will serve no useful purpose in a few years (sometimes less).

I also find it hard to summon up much pleasure in the accomplishments of my technology as (to take one example) it spits out textbook solutions to navigational challenges.

Particularly if I'm sailing alone, it leaves me feeling perilously akin to a bit-player in the story of my life.

I suppose that partly reflects the sort of challenges inherent to the places I prefer to sail.
If I was forever threading the gauntlet of congested traffic separation lanes, I would be reaching for the technology with as much alacrity as anyone.

Those challenges arising from other seafarers, enabled by technology, are probably best met by similarly smart tech. These challenges are written by humans.

But when the challenges are organic, chaotic and unruly, as served up by nature and random circumstance, I prefer to approach them with my own comparably unruly skillset, typical of an organic lifeform.

And, to me, a magnetic compass is the nearest thing to authentic magic, far more so than a gyrocompass.

It's like perfect pitch, as opposed to relative pitch.
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