Calculating Compass Headings?

[nolatom]

"How is the visibility?", would be my first question. If good vis, then "Close enough for government work" "intercardinal" headings (N, NE, E, SE, etc) and rough distance estimates should work to get you within visual range of your next target.

If vis is crap, then you need to be accurate. As said above, plan a route to see them in a particular sequence, and write in the compass course and distance between each. And know the variation (diff between true and magnetic North) in your area. If it's less than 5 degrees, don't sweat it.

I took a Power Squadrons course at age 14 (two years too young to get a certificate, but not too young to learn ;-). It enabled me to plot courses and distances for sailboat deliveries when I was entrusted to do them a few years thereafter. Compass work is very satisfying once you get the hang of it.

See if there's a Power Squadron or Coast Guard Auxiliary course in your area. Or I think you can try it on line. I would recommend it to any diver, especially if you are also going to also have/operate a boat.

 

[caruso]

If they had all the headings and measurements dead nuts, there would be no learning process for navigation skills nor for a DM Candidate to complete their Dive Briefing module.

there’s plenty of initial clues and notations to work with, to build on to create your own, much more complete dive site map.

I don't know about that. If there were accurate compass headings on the map it would be an excellent opportunity to execute a dive and navigate to each wreck underwater after jotting them in a slate.

Learning to navigate isn't about designing scale dive site maps.

As to your other point I have no clue what a DM Briefing module might be but I'm thinking it could still be done even if compass headings are provided?

 

[BlueTrin]

You can use Google Maps aerial view to get a more accurate image for the perimeter of the lake, and also correctly oriented. Then you can create your map to scale based on the various distance and headings from the billboard map, assuming they are accurate of course.

Also, assuming that Google is true north and your map photo is magnetic north, you can be more exact by adjusting for the local declination. Looks like magnetic north there is about -3° from magnetic north, but go ahead and double check that.

I didn’t know about True vs Magnetic North.

Thanks for the post

 

[BoltSnap]

I didn’t know about True vs Magnetic North.

Thanks for the post

It doesn't matter at all in the distance you are concerned with when swimming underwater on Scuba. This may matter when navigating longer distances on a boat or a submarine but not when swimming with fins on scuba.

 

[JackD342]

I didn’t know about True vs Magnetic North.

Thanks for the post

Changes over time too.
magnetic declination map - Google Search

 

[JackD342]

It doesn't matter at all in the distance you are concerned with when swimming underwater on Scuba. This may matter when navigating longer distances on a boat or a submarine but not when swimming with fins on scuba.

Depends on where you are. Continental US variance can range as much as +/- 17 degrees. Other locales can be far greater.
Just in our local quarry, most of my point to point navigation swims would be unsuccessful if I was pointed 15 degrees off. Now with same visibility as in the Caribbean, that would be very different.

 

[BlueTrin]

It doesn't matter at all in the distance you are concerned with when swimming underwater on Scuba. This may matter when navigating longer distances on a boat or a submarine but not when swimming with fins on scuba.

I think it depends of your vis ? We have notoriously low vis on the south coast of England.

I checked and the difference between true and magnetic north is low in the UK, so that’s not an issue when diving locally

 

[BoltSnap]

I think it depends of your vis ? We have notoriously low vis on the south coast of England.

No, nothing related to visibility, I meant that the magnetic declination value isn't a factor for swimming when fins underwater for the very short distances we cover under water. When you take a heading with a compass on the surface to your destination and then go down and follow the same course to the destination, magnetic declination isn't a factor. When you turn back to swim out on a reciprocal course, it is still not a factor.

If you are on a boat and using charts for navigation on longer distances, you will need to account for the declination for even small variance may cause great variance from the destination causing you to not find the exact point you were going to because of the magnetic declination.

 

[BoltSnap]

NCEI Geomagnetic Calculators

 

[BlueTrin]

No, nothing related to visibility, I meant that the magnetic declination value isn't a factor for swimming when fins underwater for the very short distances we cover under water. When you take a heading with a compass on the surface to your destination and then go down and follow the same course to the destination, magnetic declination isn't a factor. When you turn back to swim out on a reciprocal course, it is still not a factor.

If you are on a boat and using charts for navigation on longer distances, you will need to account for the declination for even small variance may cause great variance from the destination causing you to not find the exact point you were going to because of the magnetic declination.

If you have 17 degrees deviation you may miss your spot in low vis unless you target something very large ?