Compass Calibration

D

Danno

Member
Joined
Sep 5, 2002
RO Number
10045
Messages
274
Okay, so I just finished installing a SIMRAD AP14 auto pilot which has its own compass and provides a heading display. This will make a total of 3 compass displays at the helm plus 2 COG displays from the chartplotter and GPS heads.
The compass display
1. Magnetic Ritice(sp?)helmsman - Globe/reference marks
2. KVH Azimuth digital fluxgate w/display and NMEA interface with chartploter - Electronic
3. Simrad auotpilot compass - Electronic

The magnetic globe would need to be calibrated by a professional which I understand is very costly and no one locally qualified.

The electronic one can be set programmed with an offset to display correctly. However to do so I need a good or known bearing to base it off - which I don't

I am thinking to use a hand bearing compass set on center line which I would string from bow tip to stern center and use that. But any good hand compass is very expensive and not worth the purchase for one time use.

Any suggestions?

BTW I am in Oceanside, NY in case there is someone with local knowledge.
 
Your GPS will give you a good heading in no wind/no current conditions running at a decent speed. Your simrad and the gps should give equal readings in those conditions.
 
The GPS should have an option for true or mag display.
 
Not if you are using it to calibrate a magnetic compass.
 
The more I think about this, the more I realize that we probably should be recommending a good hand bearing compass. As we have said a few dozen times here, every boater should have a set of paper charts and the knowledge to use them. That includes the ability to take a position fix from a couple of points on shore and to use a beam bearing to get an estimated position. The problem with most cheap hand bearing compasses is the accuracy. Most have cards that have 5 degree increments. Weems makes one with 1 degree increments and is under $100

http://www.boatfix.com/bykeywordnew2.asp?textfield=weems+hand+bearing&texttype=2&submit=Search

I'd consider a hand bearing compass a piece of safety equipment, invaluable should your electronics fail. It's not a "one time use" device because you should also check the accuracy of your primary compass once a month.
 
Ya know, Bill, you raise a very valid point. I do enjoy plotting on a chart. In fact, I just plain like charts. While, as a guy, I know where very few things are in this house but I do know where my Nav kit is. There's something magical about a good set of dividers and a parallel rule. The same with line. At a minimum, every boater should know how to splice a line and to finish it with whipping. It's always nice to show that you are a mariner by having a couple monkey's fists on board as well as a mat or two. Here are a couple that I made when the wife told me to get rid of some of the line I had in the house

mats.jpg
 
Nic, you may be confusing terms, at least as far as compasses and navigation are concerned. Variation is the effect of the earth's magnetic field on your compass, deviation is the effect of local magnetic fields on your compass.
 
Scott, I have never had an anchor. I'm at the age where, if I stop, I fall asleep.

Thanks, Bill. Unfortunately both are relegated to the basement, which is why I could find them so quickly. The bottom one took about 60' of line. I wish I still had some of the monkey's fists I made, from little ones to big ones. I made one once out of 1/2" line - it was about the size of a soccer ball. That's what happens on a 340' cajun dive boat out in the gulf on a day too rough to dive. You get to learn all sorts of stuff.
 
You must log in or register to reply here.
Back
Top