Compass recalibration for deviation

[capt chris]

Hey everybody,
I'm putting my Lowrance GPS/Sounder and my ICOM VHF in the electronics box of my Tournament 225. That will place them pretty close, < 3 ft, from the compass. Does anyone feel it absolutely necessary to have the compass recalibrated for any possible deviation caused by the electronics?

 

[Tashmoo]

If you want the compass reading to mean anything yes, absolutely you need to have it done. Once you introduce an electric field in proximity to the compass it will be affected.

 

[capt chris]

Tashmoo,
Is it an expensive proposition to do this? What sort of folks are competent to perform such a service?

 

[Tashmoo]

I have a buddy that owns compass business in Maine, adjusting and repairing is his business. To adjust the compass is quick around an hour if nothing major is affecting it, then he takes the boat out and runs it through its paces for another hour. So all in two to three hours at $90/hr.

 

[Anonymous]

Yes.

 

[freddy063]

your new Lowrance GPS/Sounder should have a gps compass build into it. Once you get everything installed you can check the two again each other and see if it affected anything. If it seems to be off then worry about it then. I'm not sure but I think the GPS compass is true north so you would have to convet to mag to check them together.

 

[Tashmoo]

All true above, but remember one thing on this issue. The accuracy of your compass only matters when you need it the most.

 

[capt chris]

your new Lowrance GPS/Sounder should have a gps compass build into it. Once you get everything installed you can check the two again each other and see if it affected anything. If it seems to be off then worry about it then. I'm not sure but I think the GPS compass is true north so you would have to convet to mag to check them together.

Freddy you are right. I can set the Lowrance for either True or Magnetic. What is an acceptable amount of deviation? I have always heard it to be 5 degrees or less.

 

[BobP]

How do you know the radio will effect it?

Take the radio in your hand with a cord powered up, stand well back from the bridge with your arm extended, them walk the radio to where you will mount it while watching the compass - don't look away, did the compass deflect ?
Turn radio on and off, does it matter?

My hardtop box is challenged in meeting the 3 foot guideline with the compass directly below it, and it is loaded with electronics including the VHF radio.
I had a big old Raytheon raster scan radar monitor less than a foot away from the compass, right next to it on the console. I have a stereo radio in the console box now, less than foot away.

None of these components failed the DIY test I suggested.

I did have trouble with box stereo speakers and a previous VHF radio aux speaker. The compass went crazy well back.

Even though I used the Planer shielded speakers, I had to mount them off the bridge, actually down next to the seat pedestals.

Never give up your compass to anything electrical, you will find out one day why, when loss of power or gremlins take over your electronics.

 

[MRT]

Compass deviation may vary depending on your heading in addition to the eqiupment and electronics that are in use. Be sure to understand the deviation at least at N, S, E & W headings with your normal equipment & electronics load.

 

[BobP]

I presume the compass was adjusted when originally installed per manuf . instructions.

After you verify the equipment's effect while at the dock or driveway, take the boat our for a ride with no wind, no waves, and no current, verify GPS heading against compass reading and different headings.

Close enough?

 

[MRT]

I think you would get better results away from the dock & definitely away from the trailer.

 

[enfish]

You can calibrate it yourself and save the cash plus the hour gas burn. Ritchie has instructions boxed in , also on the website. If all fails than you could hire the professional. I always say..the professional had to do the first one..and I am not talking about just compass adjusters either..professionals at anything. I have found the bark is generally worse than the bite.

Pete

We had a deviation in our compass of about 20 degrees at some headings when we installed an external VHF speaker 3 or 4 feet away. We followed the instructions from the Richie website while the boat was on the trailer in the parking lot. The whole procedure took about 10 minutes, and was then verified on the water. The deviations after calibration were less than 1 degree for all headings, so the trailer did not appear to affect the compass readings.

Eric

 

[MRT]

...so the trailer did not appear to affect the compass readings.

Eric

Any chance you have an aluminum trailer? Aluminum, brass, bronze are non magnetizable thus should not influence your compass reading. Normally, to get the best results all magnetizable materials not normally in the boat when in use should be kept away.

 

[enfish]

...so the trailer did not appear to affect the compass readings.

Eric

Any chance you have an aluminum trailer? Aluminum, brass, bronze are non magnetizable thus should not influence your compass reading. Normally, to get the best results all magnetizable materials not normally in the boat when in use should be kept away.

Nope, galvanized steel trailer. We tried it in the parking lot first because it was easier to hold a constant heading and adjust compensator screws. The worst case was that if it didn't work, we'd have to do the process again in the water, but would have been experts with the practice in the parking lot. Turns out the parking lot worked just great

 

[freddy063]

how big is Lake Cumberland, Ky, is tha the only place you boat?

 

[capt chris]

how big is Lake Cumberland, Ky, is tha the only place you boat?

It is about 100 miles long and covers 55000 acres @ full pool. It has approx 1200 miles of shoreline and by volume is the largest lake east of the Mississippi. It is a corp lake so access is very restricted and that's what has kept it so great. It is a world class striper fishery w/ the record being over 50 lbs. I keep my boat there and we have a cabin there so I don't boat really much of anywhere else.