Comp. Interferes w/ Compass?

[scuba-sass]

Well, a rather odd thing happened recently. My partner and I have exactly the same gear (BC's slightly different for fit), and we both experienced the same problem. When we did our OWC dives back in October, we didn't yet have computers. Our compasses worked fine.

In December, we purchased Oceanic Data Plus 2 computers. In the console, the pressure guage and computer are on one side, and the compass is on the reverse, directly behind the computer. To be honest, we've done 20+ dives since then, but they've all been with DM guides, and we haven't used the compasses.

Fast forward to about 2 weeks ago. We sit in our Navigatioin class (computers off), and the compasses work fine. Three days later, we're geared up, computers turned on, and about to get wet for our Navigation Dives. We take readings from the shore, and North isn't in the right place - for either of us. Then (while we're standing still), North spins around 180 degrees!

Did anyone else feel the earth move on Friday, July 5th?

So, we completed our Navigation Dives sharing our Instructors spare wrist compass between us. (Thank God we didn't drop it when we switched navigators!)

Our LDS switched to a different console, different compasses and could only conclude that the almost back-to-back proximity of computer and compass caused the problem. The new consoles have the compass elevated and off-set, so it's no longer quite so close to the computer.

Any one ever have a similar experience? Any thoughts on this puzzle?

Happy Diving,
Scuba-sass

 

[O-ring]

So, we completed our Navigation Dives sharing our Instructors spare wrist compass between us. (Thank God we didn't drop it when we switched navigators!)

When my gf and I did AOW, I had a wrist mounted compass and she had a console flip-over type like you mentioned. We were always a little off of each other too, but the instructor attributed that to my "using an inferior wrist mounted compass" and told me "if you don't own that compass, I would invest in a good console, it is much better than wrist mounted instruments because it keeps everything together in one place".

Maybe we were really off due to the interference you mentioned....I know that if you get one too close to a wreck or a scooter it can do funny things..

 

[dkerr]

When you said the compass was 180 degrees off that makes me think that you are looking at the compass wrong. Some compasses are made to look at from the top and others (reverse bezel?) are made to look at from almost behind. This is done by holding the compass almost at eye level and looking through the little viewing window. This alows you to get a bearing and aim at a target to swim towards simultaneously.
Of course it could be deffective, but if both compasses were 180 off, this is probably the case.
Take care and happy navigation!!!

 

[scuba-sass]

I'm aware of the interferance wrecks or other large bodies of metal can have with a compass. We were at this site for our Navigation Class (Nubble Light in York, ME) because you can use a compass there with little or no worry about this.

Besides, we were not "just a little bit off" - we were way off, and our 2 compasses did not agree with each other, nor did they remain constant. The lack of constancy was what made them impossible to use.

Since my LDS had never seen this happen, I'm curious if anyone on this board has. I guess the suspect consoles were a reasonably inexpensive model, and usually folks who buy that don't also spend the $$ on computers. So their only comment was that out of the few folks who might have our same combination of equipment - maybe no one ever paid enough attention to the compass to notice the problem!

Happy Diving,

Scuba-sass

 

[scuba-sass]

dkerr,

Sorry, you were posting at the same time I was. It was not an error in reading the compass. I'm not sure of the specific errors on Lydia's, but mine started off approximately 90 degrees off, held steady for a few seconds, then swung around about 180 degrees (45 degrees off in the opposite direction, of course!), then wavered around between those 2 points.

Now before you all start asking....

Yes, we held them steady.

Yes, they were properly level. After all, we were standing on the shore, barely wet. We weren't bobbing around in the surf.

Yes, our instructor tried both himself, and even he couldn't make sense of them!

Thanks to all!

Scuba-sass

 

[dkerr]

Deffinately sounds like a problem then. Sounds like you know what to look for so good luck

 

[Dryglove]

Like you said there is definitely a problem there.I would take them back to where you purchased them from or get a hold of the manufacturer to get the problem resolved.It sounds to me they have had a problem and that is the reason for the redesign or maybe its just a bad batch of compasses.

I had a bad compass but it was real slow to respond and turn.Hopefully the dealer you bought it from or the manufacturer will stand behind there product and treat you right.Good luck!!

 

[Padipro]

When I was doing my Advanced Openwater course some years ago no matter what I did I just couldn't get the Nav part. This really ticked me off because I work on aircraft for a living and I know how a compass works and I couldn't figure out what I could be doing wrong. After several attempts and a very agitated Instructor I finally figured out that it was my wrist watch which was on the same arm right next to my compass. After that I never put anything next to my compass again and I've never had trouble again.

Scott

 

[scuba-sass]

Could it be true that no one has had something like our situation occurr? It simply had to be the close proximity of the computer, but is there really enough metal in one to effect a compass?

Any thoughts?

Scuba-sass

 

[Narced]

when you think about all of the compasses and all of the computers out there, as well as different console boots, it is certainly possible no one else on here has had this happen. Rather than metal in the computer it is probaly electrical current. I was refilling my compass with oil last night (long story of stupidity on my part) and with the oil out the compass can spin very freely and easily. I have alot of electronic gear in my house and wherever I went on the ground floor of my house the north still pointed north, but was sometimes a bit partial to some of my equipment that was on. With the oil back in it was less noticeable, but still apparent.

With this in mind I see no reason why a dive computer puck placed back to back with a compass would not be capable of causig a disturbance. If it does it is a poor desing of a dive computer in my opinion, but nonetheless I certainly believe your account of what happened.