Set HDG Mag or True?

[SkunkBoat]

I recently went thru all my devices (2 MFDs, GPS, radar, AP) and changed setting from Magnetic to True.
You definitely have to do them all at once!!!

My reasoning:
Mag deviation variation is 13 degrees West here. If heading 0 degrees Mag the chart displays a course slightly left of North.
I'm always looking at the chart plotter not the compass. It seems more relevant to use True so that a 0 degree heading is straight at the top of the screen ( I always use North Up too..)

Opinions? Drawbacks?

 

[seasick]

I would think that as long as the MFDs and AP use the same option, things either option will work. Personally, I use my compass all the time since it helps to have the MFD set to magnetic north so that it aggress with the compass. Although my brain says it is better to use north up from a navigations point of view, my brain also has problems determining which way to turn to follow a course or backtrack over a previous track.
I have tried two MFDs, one north up and one heading up to see if that made interpretation better. That just caused a brain short circuit

 

[wspitler]

First, make sure you understand the difference between variation and deviation. What you are talking about is variation not deviation. Variation is a function of where you are on the earth and changes over time. Your compass deviation is the difference between magnetic and the compass reading. As taught in basic navigation, CDMVT ( can dead men vote twice) is one way to look at it. Compass adjusted for Deviation equals Magnetic adjusted for Variation equals True. All fluxgate heading indicator’s actually indicate magnetic not true. However virtually all compasses have some degree of deviation that varies with heading.

 

[SkunkBoat]

First, make sure you understand the difference between variation and deviation. What you are talking about is variation not deviation. Variation is a function of where you are on the earth and changes over time. Your compass deviation is the difference between magnetic and the compass reading. As taught in basic navigation, CDMVT ( can dead men vote twice) is one way to look at it. Compass adjusted for Deviation equals Magnetic adjusted for Variation equals True. All fluxgate heading indicator’s actually indicate magnetic not true. However virtually all compasses have some degree of deviation that varies with heading.

I stand corrected! I used the wrong word even though I know the difference. I mean Variation

 

[SkunkBoat]

I have tried two MFDs, one north up and one heading up to see if that made interpretation better. That just caused a brain short circuit

Both have their advantages and disadvantages.
I like to see the boat turn on the chart rather than have the chart spin
When radar overlay is on, North Up isn't useful.
For navigation I use a 3 way split screen with a large North Up chart and a smaller heading up and sonar. The large North Up chart gives you situational awareness. The smaller heading up works well when you have a bearing to waypoint line. You just keep the heading straight up( like a lubber line). Easier than looking at a compass.

 

[wspitler]

I like to use head up with a projected GPS course over ground (COG) line that indicates two minutes, one mark for each minute. I find it real valuable for zooming in to hit a fishing Mark with high degree of accuracy. We have quite a bit of current offshore at times and heading is not as meaningful as projected GPS course, particularly at slow speeds. I could only get my flux gate compass deviation down to about 6° max on certain headings due to location and other ferrous objects.