Is that so? No, it's not. How could the deviation table be on a chart when it's specific to your boat?
What is on the chart is a compass rose that shows both true and magnetic direction, and indicates the local magnetic variation.
Compass, AP, GPS conflict
- Thread starter KennyBene
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What is on the chart is a compass rose that shows both true and magnetic direction, and indicates the local magnetic variation.
NROTC stopped teaching it about 2000, USNA stopped in 2006, and they both started again in 2016.
OMG @jviss this is my last comment on your responses
Sextant...
https://www.amazon.com/Davis-11-Mar...e=UTF8&qid=1532295158&sr=8-5&keywords=sextant
I just download from NOAA a current Navigational Chart from..
http://www.charts.noaa.gov/ChartCatalog/GulfCoast.html
I download chart #11143
There are 5 deviation corrections on that chart. Here it the upper right one for example.
If YOU are in the Northern Hemisphere you can use the North Star, Cassiopeia, Ursa Major to locate North, then by a simple drawing protractor estimate the angle and time of day, Date and year... then locate your Latitude... etc .....
Remedial lesson endeth.
Jim...
PS: I was a Naval Line Officer.
Sextant...
https://www.amazon.com/Davis-11-Mar...e=UTF8&qid=1532295158&sr=8-5&keywords=sextant
I just download from NOAA a current Navigational Chart from..
http://www.charts.noaa.gov/ChartCatalog/GulfCoast.html
I download chart #11143
There are 5 deviation corrections on that chart. Here it the upper right one for example.
If YOU are in the Northern Hemisphere you can use the North Star, Cassiopeia, Ursa Major to locate North, then by a simple drawing protractor estimate the angle and time of day, Date and year... then locate your Latitude... etc .....
Remedial lesson endeth.
Jim...
PS: I was a Naval Line Officer.
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That's not the same sextant link you posted previously. And, that plastic Davis you now link is not a very serious instrument, either.
It wouldn't be so bad for you to be so stridently pedantic if you were right. But on that chart, Captain, is shown the MAGNETIC VARIATION, not DEVIATION. That's what "VAR 6º 00'W" means. Unless you are going to argue that "var" is the abbreviation for "deviation."
I honestly don't understand why you are so upset with me over this.
@JamesG161 not to stir the pot, but to put some oil on the water (metaphorically speaking of course). The compass rose you posted shows variance, not deviation. Unless of course NOAA has a strange sense of humor about abbreviating deviation with VAR. Easy mistake to make, I get the confused sometimes, too.
Lesson #2....
Using that Table in a 360° form... [easier form when plotting a charted course]
Deviation is shown as the black thin vertical line showing, the actual deviation when the chart was last updated in
2015
lets do the math...
2018 - 2015 = 3
Annual deviation is 6' . Plus a general knowledge of where you are at on that chart, ie North Hemisphere Western Half.
3 x 6' = 18' correction ADDed to your Compass Bearing....[if use my post #36 above to remember to ADD]
I only responded out courtesy to @dlochner
Bye from this thread...
Jim...
Using that Table in a 360° form... [easier form when plotting a charted course]
Deviation is shown as the black thin vertical line showing, the actual deviation when the chart was last updated in
2015
lets do the math...
2018 - 2015 = 3
Annual deviation is 6' . Plus a general knowledge of where you are at on that chart, ie North Hemisphere Western Half.
3 x 6' = 18' correction ADDed to your Compass Bearing....[if use my post #36 above to remember to ADD]
I only responded out courtesy to @dlochner
Bye from this thread...
Jim...
Yep deviation is a variable on your compass in table form created by you to show deviation from magnetic north for various heading around the rose and is caused by the local (on board) influences of metal on your boat. Specific for each individual boat as currently configured. Cannot use on another boat or if you move a lot of metal around on your boat.