Compasses and Zones

[Random Dude]

Hi all, need some advice on purchasing underwater compasses.

Was wondering would there be any scuba compasses that would be usable in all zones around the world?

Initially thought that the Suunto SK8 was a global needle, but further checking the web shows that they are still calibrated in 2 zones, either northern or southern hemisphere.

What about the ScubaPro FS2? It is indicated as being able to deal with high levels of tilt, but would that be sufficient to counteract the effect of switching zones?

I'm asking about these 2 brands specifically as they seem to be the most popular compasses for now. Any other brands of compasses that can recommended as having a global needle would be welcomed too.

Would appreciate it if someone could shed some light on this, thanks a lot!

 

[ScottFL78]

You are talking about a regular magnetic compass right? Are you talking about zones in reference to the difference between magnetic and true, or grid North?

 

[Random Dude]

Yes, talking about a regular magnetic compass, but searching for one with the ability to work in all zones and not stick when I move to different zones in the world.

As for zones, I'm referring to the artificial zones that manufacturers make up in order to counteract the fact that Earth's magnetic pull is not uniform around the globe, and does have vertical components.

For example, when you move further North, the compass will be pulled vertically downwards in the North direction, making it more likely for the compass to stick/ not rotate freely.

I've included a couple more threads below as they probably explain the subject far better than me

Compass Balance And World Zone Chart
Understanding balancing zones
Compass Zones Explanation from Facewest: Fast Free Shipping and Great Service

 

[elmo]

The difference is only few degrees at most anywhere you're likely to be diving. And it only matters if you need that sort of absolute accuracy (e.g. detailed survey) and don't want to have to correct it later. If you just want to navigate out and back (or box, etc.) then it makes no difference because the inaccuracy is constant throughout the dive.

 

[stuartv]

DGX Tech or Deluxe

Underwater Navigation Compasses | Dive Gear Express®

Or a Perdix...

 

[Altamira]

From my experience, using a dive compass is somewhat different than using a compass on dry land because underwater, you normally do not have a flat surface to lay the compass on. Mounting the compass on arm, computer, or slate usually results in a compass that is not oriented perfectly level. As it is, it is not easy getting the compass perfectly level underwater, and to solve any sticking issues, you may have to slightly tilt the compass to insure the needle is free floating. You can easily see if the needle is sticking by changing the compass orientation approximately 45 or 90 degrees. I use those two degree changes because one half quadrant and one quadrant changes are easy to see. I have used my "northern hemisphere" dive compass in Australia, without problem, and had no issues with the needle sticking to the point of making my compass un-useable.

 

[jfe]

IMO it is not a consideration at all, I dive both hemispheres and use a compass from the south and never had issues in the north. As stated you are not pin point accurate anyhow, but you also won't get lost. If you were to swim in a straight line for 15km or 10 miles it may have an influence, but most people cannot even do that on dry land. Sometimes I believe a lot is sales gimmics

 

[The Chairman]

You're way overthinking it. Any compass will be sufficient for underwater navigation.

 

[Random Dude]

Thanks a lot guys, seems like I've been overcomplicating it

Glad to know that the zone differences are not as pronounced in the real world, will grab the next great deal on diving compasses I see!

 

[CT-Rich]

The only time it would POSSIBLY make a difference is if you were trying to pull a heading from a chart. If you take a visual bearing it will make virtually no difference. As for sticking, change the orientation of compass. It might make sense for the manufacturers to have multiple zones, since they don't want to sell a consistently inaccurate device to the public.