Compass reading 180 degrees off???

[The Kraken]

A bubble will not have any effect upon the condition which the OP puts forth.

That which the OP states would have to be a manufacturing defect. And if this were the case, there would be hundreds, if not thousands of consumers reporting this particular phenomenon.

the K

 

[Charlie99]

It has a HUGE arrow that points North. That and when I take my azimuth at the surface, I set my outer ring to match so I am 100% sure I don't just get turned around on a descent.

.............

Also, in the VT3 trans mount, it is extremely difficult to read the compass through the side window, so I read it from the top since it's on a retractor.

When you take your azimuth at the surface are you doing from the top, just like you read it when at depth, or do you take your surface bearing through the side window of the compass?

 

[diverdown247]

When you take your azimuth at the surface are you doing from the top, just like you read it when at depth, or do you take your surface bearing through the side window of the compass?

Always read from the top due to the VT3 transit clip/mount. I also read it from center body to get the most accurate reading and leveling possible.

Before anyone asks, it is nearly impossible for me to have rotated 180 degrees using the bouy cable and sun as reference points. Especially knowing that the boat dock cables pointed East from the bouy.

I will be diving the site again this weekend to see if the issue occurs again.

 

[cummings66]

I misread, he did indeed say he could watch it turn 180 at 30 feet and it was fine above that depth. I'm at a loss other than the bubble theory, the bubble could trap the disk and keep it from moving and then once it's small enough the compass would turn again. There is little else, magnetism isn't going to change magically at 30 feet, plus I dive where he does and my compass doesn't change at all. There is only one thing that changes, that's pressure.

I've seen a lot of different size bubbles in compasses and I believe it could trap it easily enough if you're not absolutely level.

 

[Doug Krause]

Sorry for not jumping in sooner - I've been watching this, and saw that everything that I could have contributed was being posted by someone - which I appreciate tremendously. I had assumed after my first read of the original post that this related to the markings as viewed from above or through the side window as was posted previously. Reading through the original post more carefully as I should have done in the beginning - I have found a couple of key words that have to considered: metal runway parts. The compass magnets reacting to metal in the vicinity is my only possible explanation - and highly likely considering the environment.

Doug

 

[Dive-aholic]

There's a lake a couple of hours from me where something similar happens to me. There's some type of metallic ore in the ground that throws the compass off. At certain points in the lake, if I'm following my compass, which is common due to the lack of visibility, I start swimming in circles because my compass is turning. It took me a couple of dives to figure out what was going on. It only happened in one small cove in that lake.

 

[cummings66]

Yeah, but this is different. It's 100% until he hits 30 feet then it swings 180 degree's. That's not how magnetism behaves, it's effects are subtle and increase in strength as you get nearer. It can not be right then wrong like magic. Take a small magnet and a cheap compass and move towards and away from it to see what I mean. Don't use a good compass, magnets can make a compass lose accuracy, not that I believe a scuba compass is as good as my orienteering compasses or my plane's compass.

I've been around compasses all my life and have flown over areas with anomalies and the compass will misbehave subtlety until you get very close then it goes crazy. I have never seen it rock solid and then swing 180 all of a sudden.

A better question to ask is this, what does the compass do as you go above 30 feet? Will it suddenly correct itself? I guess one possibility is that you're descending on TOP of the anomaly and it could do this then, but if you're to the side it can't do it as described.

 

[Doug Krause]

Diverdown247 -

PM your mailing address - I will be glad to send out a replacement compass module for you to try to see if this is duplicated with another. If so, I think that we can safely assume that it is not a problem with the compass.

Doug

 

[Dive-aholic]

Yeah, but this is different. It's 100% until he hits 30 feet then it swings 180 degree's. That's not how magnetism behaves, it's effects are subtle and increase in strength as you get nearer. It can not be right then wrong like magic. Take a small magnet and a cheap compass and move towards and away from it to see what I mean. Don't use a good compass, magnets can make a compass lose accuracy, not that I believe a scuba compass is as good as my orienteering compasses or my plane's compass.

I've been around compasses all my life and have flown over areas with anomalies and the compass will misbehave subtlety until you get very close then it goes crazy. I have never seen it rock solid and then swing 180 all of a sudden.

A better question to ask is this, what does the compass do as you go above 30 feet? Will it suddenly correct itself? I guess one possibility is that you're descending on TOP of the anomaly and it could do this then, but if you're to the side it can't do it as described.

Maybe I missed it, but I didn't read where it swings 180 all of a sudden. The OP just states that by the time he's at 30-35 feet, it's 180 degrees around. It could have been a gradual movement during the descent.

 

[diverdown247]

Thanks everyone for posting up on this. It is definately a strange issue all together. I will be diving this Sat/Sun so I can post up on Monday the results of my "test" from Sunday's venture.

I will be taking at least 2 different brands of compass if not a 3rd on my backup reg. My Zeagle is a pop-out, so I can toss it in a pocket and go. Naturally, if there are issues with both compasses at the same time, then it is an issue with the general area and I will post up a notification for the exact area. GPS coordinates if one is available.