compass calibration

Kwiksilver · 05-20-2005, 09:41 AM

I have an alum, boat and a ritchie compass when I run my windshield wiper the compass goes crazy.I have tried everything they say to do to no avail.Could one of the experts please tell me what I need to do I have to have my compass plus it's become a mission now to whip this thing

.Thanks Scott

Orca · 05-20-2005, 09:49 AM

I don't think there is a quick fix. You need to move the compass further away from the wiper motor. Or, get a fluxgate compass.

Nalu · 05-20-2005, 09:50 AM

The compass on our sled is mounted directly below our wiper motor and it has no issues.

Where is the compass light grounded and wired to?

If you disconnect the wiring, and it still goes crazy, I would try to take it from its mount, then run the wiper holding it close. I can't imagine it will still fluctuate. Sounds like stray current to me, either in the wiring, or coming through the boat.

If it still fluctuates while you are holding it, then Orca probably has your only answer.

Kwiksilver · 05-20-2005, 09:55 AM

Thats just it I don't even have power to it yet.Is it possible it might be a bad compass?

Sensei-san · 05-20-2005, 10:05 AM

Nope... As Richtie says in their ad... "I will never fail you." The previous post was probably on the money. Any motor will create magnetic fields. Better motors have shielding that will attenuate the magnetic fields. I would check your wiring first and make sure that the wiper motor is not connected to the compass lighting. Make sure that there is a ground to the case of the wiper motor and it is connected to the common ground. The power to the wiper motor should be connected as direct as possible to the battery.

A fluxgate compass would solve most of the problems as it uses a different method to detect the magnetic field. But it is dependent on electricity.

Pilar · 05-20-2005, 10:23 AM

Any magnetic field local to your boat will influence your compass. The earths' magnetic field which moves the compass card is pretty weak compared to the artificial ones generated on your boat that are close to the compass.

All DC powered devices give off magnetic fields when under power. These may or may not affect the compass depending on how far away, how well shielded they are and what orientation the magnetic field is to the compass. The wiring to the device will also give off a magnetic field when power goes through it. Speakers and microphones give off a passive magnetic field due to the permanent magnets they contain. Mounting a speaker near your compass is a bad idea. Even steel fasteners and steel in general can be a source of magnetic fields. On an aluminum boat this problem is minimized but watch out for steel fasteners.

Your car keys or a tool on the dashboard can even cause problems.

The other thing is to choose the mounting location wisely. Place the compass in any desirable place and watch carefully as you flip each switch to each item on the boat. Any deflection on the compass and you will have a deviation when you run that item and try to use the compass at the same time. Pick a spot where the effects are minimized.

You can minimize these effects by twisting the + and - wires together when they run anywhere near the compass. You can also reroute wiring so that it is at least a foot away and move any high current wiring as far as possible from the compass. For the compass light itself consider using a twisted, shielded wire for the connection. Belden makes this wire and it is typically used for the signal to sensors and actuators in a control system. Platt electric will have 2 conductor 18 gage twisted shielded wire for like a buck a foot.

Think magnetic fields and see if you can figure out where the interference is coming from.

Bait O' Eggs · 05-20-2005, 11:32 AM

When running in last weekend I noticed my compass off about 40 degrees from the one on the GPS/fishfinder/plotter unit.

Had me puzzled for a moment till I noticed I placed a 25 foot tape measure in the holder next to the compass

Gonna have to get me a different halibut measurer

BrianH · 05-20-2005, 11:55 AM

Quote:

Think magnetic fields and see if you can figure out where the interference is coming from.

Reminds me of a time when I was an electronics technician at a local manufacturing plant. The boxes we were working on had displays. One time when the boss came by, I remarked "Got a real doozy here Bill." I then ran my magnetic, fairly strongly magnetic, screwdriver all around the edges of the screen. It caused the display to warp and bend. Looked like a really complex problem, to the Management anyway.

Yeah, it was tough, but I got it fixed.