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Old 10-03-2015, 12:37   #61
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Re: True or Compas

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Portland plotters are the only way to go on a small boat. One advantage is that you can 'mark' your variation on the plotter and lay compass bearings directly onto the chart as true bearings.... if you still do stuff like that.
Yes I do do stuff like that. I haven't bought a Chartplotter yet. One day I will, I just haven't needed one more than I needed the thousand bucks yet, so I use my charts quite a bit still. I think I even have one of those plotters I got at a trade show. I'll try it out and maybe do a review on it if it's awesome.

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Old 10-03-2015, 12:57   #62
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Re: True or Compas

OK ya draw da line on da paper.

How the heck do you know it's true or magnetic?

You refer to the LABELING of the line.

Which is determined by the rose.

Any given LINE will have two #s associated with it: T or M

But it's still the SAME line.

Again, unless you're sailing LONG DISTANCES across areas of changing variation, and certainly for short coastal hops, T or M make no difference.

If you're sailing LONG DISTANCES you should use T.
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Old 10-03-2015, 13:07   #63
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Re: True or Compas

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Originally Posted by FamilyVan View Post
Yes I do do stuff like that. I haven't bought a Chartplotter yet. One day I will, I just haven't needed one more than I needed the thousand bucks yet, so I use my charts quite a bit still. I think I even have one of those plotters I got at a trade show. I'll try it out and maybe do a review on it if it's awesome.
I use mine for laying off courses, pretty rare to put a bearing on the chart as I am usually either 'off soundings' or in pilotage waters using transits and stuff.
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Old 10-03-2015, 13:14   #64
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Re: True or Compas

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Originally Posted by Stu Jackson View Post
OK ya draw da line on da paper.

How the heck do you know it's true or magnetic?

You refer to the LABELING of the line.

Which is determined by the rose.

Any given LINE will have two #s associated with it: T or M

But it's still the SAME line.

Again, unless you're sailing LONG DISTANCES across areas of changing variation, and certainly for short coastal hops, T or M make no difference.

If you're sailing LONG DISTANCES you should use T.
You should always show your 'working'. ie next to the course line you should write down frinstance

Co 235* (True)
Var 15*W
Co 250* (Mag)
Dev 3*E
Co 247* ( Comp)

If neglible deviation just ignore that bit.

That way there is no confusion, anyone coming on watch knows exactly what is going on.
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Old 10-03-2015, 13:31   #65
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Re: True or Compas

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I use mine for laying off courses, pretty rare to put a bearing on the chart as I am usually either 'off soundings' or in pilotage waters using transits and stuff.
Ya, I do volunteer work from time to time on some local Tall Ships, either master or mate- depending on their needs (or joy rider). They're all into traditional navigation stuff, so I participate in the spirit of fun and leading through example.

In all honesty there isn't much to run into here on the lower great lakes.

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Old 10-03-2015, 16:02   #66
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Re: True or Compas

If one did not want to pollute their chart with a lot of numbers one could develop or adapt an aviation type log.

You add all the pertinent info to the next waypoint and then it is handily available.

Oh, wait. That won't work. We are sailors and have been writing on our charts since 1642...
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Old 10-03-2015, 16:36   #67
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Re: True or Compas

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If one did not want to pollute their chart with a lot of numbers one could develop or adapt an aviation type log.

You add all the pertinent info to the next waypoint and then it is handily available.

Oh, wait. That won't work. We are sailors and have been writing on our charts since 1642...
Well, if you are still using paper charts you might as well write on them....

Just don't write on top of any charted dangers is all, like HMS Nottingham's navigator did with Wolf Rock... obscured it with tidal info....
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Old 10-03-2015, 16:40   #68
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Re: True or Compas

Did anyone here actually ever got formal instruction on chart work and laying courses ? I'm astounded


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Old 10-03-2015, 16:57   #69
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Re: True or Compas

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Well, if you are still using paper charts you might as well write on them....

Just don't write on top of any charted dangers is all, like HMS Nottingham's navigator did with Wolf Rock... obscured it with tidal info....
I applaud the guy that buys a new set of global charts every 90 days but I suspect that most of us don't.

Av charts are only good for 90 days but if one flies a lot even in 30 days the chart can get very polluted with chicken scratch.

Nautical charts one may want to keep for a few years could get pretty polluted as well.

My chart only has course lines and waypoints. The navigation data is separate.

Look I will confess - I coastal sail. My trips are 50 miles a day max. I look at the chart, estimate the course line off the rose and set sail. I adjust on the fly. I keep track of where I am with MKII eyeballs. I sometimes fire up the GPS.

I have also flown distances at 300kts. You can get pretty lost in 4 hours.

At 5 kts in a sailboat, not so much. In a passage say you get it off by a degree or three. In a day you are a few miles from where you thought you'd be...

Don't get me wrong. It is important to know how to do this stuff. But getting lost shouldn't ever be a result at 5-8kts.
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Old 10-03-2015, 17:40   #70
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Re: True or Compas

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Did anyone here actually ever got formal instruction on chart work and laying courses ? I'm astounded


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I did. Now what?

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Old 10-03-2015, 17:50   #71
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Re: True or Compas

On the chart, one can label his line "T=292, M=295" etc. What's the point in arguing as we are talking about exactly the same line being plotted on the chart?

You can plot what you want, it is the same line, just label it correctly and you are fine.

More popcorn, way more...

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Old 10-03-2015, 22:44   #72
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Re: True or Compas

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Originally Posted by goboatingnow View Post
Did anyone here actually ever got formal instruction on chart work and laying courses ? I'm astounded


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No, not really. At my club volunteers teach. Since we navigated by compass in Puget Sound at the time, using magnetic involved less computing. As far as people warning about the magnetic rose being out of date, currently it will take 7 years for the rose to be 1 degree off here. Again between my ability to hold course, the 5 degree marks on the compass, and the currents around here this is way down in the noise level.

I did convince NROTC that I knew enough about DR/Piloting that they let me take their celestial navigation class when I was in college. Must have took, I didn't miss Hawaii.

Other than the above this poor recreational sailor has managed with book larnin. See my earlier post for what I learned from Dutton's stating you put the appropriate label magnetic or compass if that is how you're navigating.

I've been bamboozled. I am going to be banished from sailing because Dutton's wasn't a good enough reference to teach me proper navigation. So I'll have to take a several hundred dollar course to be allowed on the water.
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Old 10-03-2015, 23:19   #73
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Re: True or Compas

A note on marking up charts. I discovered the wonders of erasable pens for chart work recently. Just like using a lead pencil except a rainbow of different colours can be used and they don't smudge when erased. There's even erasable highlighters available! Before I discovered these and way back when I used to plot routes on paper charts all the time I would use a laminated chart and mark it up with fine whiteboard markers. When finished, I'd just scrub it off and the charts would be fresh for the next time.
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Old 10-03-2015, 23:29   #74
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Re: True or Compas

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I did. Now what?

b.
Don't worry about it, he is just being his usual objectionable self...
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Old 10-03-2015, 23:33   #75
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Re: True or Compas

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On the chart, one can label his line "T=292, M=295" etc. What's the point in arguing as we are talking about exactly the same line being plotted on the chart?

You can plot what you want, it is the same line, just label it correctly and you are fine.

More popcorn, way more...

b.
I just wrote that in longhand for the benefit of the OP and possibly others.

In fact what I would write is simply..

195*T
12*E
183*M

You know thats why there are empty bits on the chart with no soundings so you can write stuff.
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