To all Captains Commanding,
Last week the 1st. Mate and I turned the compass using the method described by Ritchie Compass. It worked very well, and was easier than I thought it would be. Amazing, the flux gate compass on the AutoHelm, the compass on the pedestal, and the GPS all now agree to North, East, South and West, haven't yet checked against the Loran! I haven't yet produced a deviation table, but may do that sometime in the future when I have nothing better to do..try it, you may like it also...
Dave Stump
Captain Commanding
s/v Hanalei CD-30C "1"
Turned compass with GPS....
Moderator: Jim Walsh
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Warren Kaplan
Re: Turned compass with GPS....
Captain Numero Uno (once known as Capt. Dave),
I read something in Sail Magazine the other day about checking a compass. Its not as thorough as what you did but it might be nice to do if the opportunity arises. If you sail in an area that has a "range", 2 day markers lining up one atop the other or 2 lights lining up the same way to mark when you are in the channel or range, this can be checked against a chart. Get out your trusty parallel rules and go to the chart. Line one leg of the rule thru the two range markers and run the other leg thru the compass rose on the chart using the magnetic ring. That will give you and accurate bearing of the range. Use an up to date (variation) chart. When on the water, when the range markers line up bow on, your compass should read what you got on the chart. Its a nice, quick easy way to periodically see if your compass has any errors since the last major "swinging".
Warren Kaplan (Capt. Numero Nothin')
S/V Sine Qua Non
CD27
Setsail728@aol.com
I read something in Sail Magazine the other day about checking a compass. Its not as thorough as what you did but it might be nice to do if the opportunity arises. If you sail in an area that has a "range", 2 day markers lining up one atop the other or 2 lights lining up the same way to mark when you are in the channel or range, this can be checked against a chart. Get out your trusty parallel rules and go to the chart. Line one leg of the rule thru the two range markers and run the other leg thru the compass rose on the chart using the magnetic ring. That will give you and accurate bearing of the range. Use an up to date (variation) chart. When on the water, when the range markers line up bow on, your compass should read what you got on the chart. Its a nice, quick easy way to periodically see if your compass has any errors since the last major "swinging".
Warren Kaplan (Capt. Numero Nothin')
S/V Sine Qua Non
CD27
Setsail728@aol.com
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D. Stump, Hanalei
Re: Sure, and don't ya know...
Warren Kaplan (Capt. Numero Nothin'),
Received your last this instant, and yes a range is a very good way to "check" a compass. But it is very difficult to turn a compass with just a range. You can't head North, East, South and West around the range. Heading to and from the point of reference.
Don't worry about the Numero Nuthin' thing. There is, I think, going to be a he*& of a race next year. Can't wait to call out the fleet!
I remain your most humble servant...
Dave Stump
Captain Commanding
s/v Hanalei CD-30C "1"
Received your last this instant, and yes a range is a very good way to "check" a compass. But it is very difficult to turn a compass with just a range. You can't head North, East, South and West around the range. Heading to and from the point of reference.
Don't worry about the Numero Nuthin' thing. There is, I think, going to be a he*& of a race next year. Can't wait to call out the fleet!
I remain your most humble servant...
Dave Stump
Captain Commanding
s/v Hanalei CD-30C "1"
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Warren Kaplan
Re: Sure, and don't ya know...
Dave,
Methinks you attach great latitude (and I don't mean nautically) to the definition of "humble" HA!
I think the idea of checking the compass accuracy in a range is just meant for a bow on bearing as that is easily checked against the chart. I don't believe they suggested swinging the boat 360 degrees as the sighting errors would probably be too pronounced. I think its just a quick interim check when the opportunity conveniently arises to see if anything is grossly out of whack with the compass.
Next year I hope to have Sine Qua Non up on The Sound. I'm gonna' lay on the slickest bottom paint you ever saw so that she'll slice thru the water like greased lightning come next year's race. I can just tell you're quaking in your seaboots!!
Warren
Setsail728@aol.com
Methinks you attach great latitude (and I don't mean nautically) to the definition of "humble" HA!
I think the idea of checking the compass accuracy in a range is just meant for a bow on bearing as that is easily checked against the chart. I don't believe they suggested swinging the boat 360 degrees as the sighting errors would probably be too pronounced. I think its just a quick interim check when the opportunity conveniently arises to see if anything is grossly out of whack with the compass.
Next year I hope to have Sine Qua Non up on The Sound. I'm gonna' lay on the slickest bottom paint you ever saw so that she'll slice thru the water like greased lightning come next year's race. I can just tell you're quaking in your seaboots!!
Warren
Setsail728@aol.com
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Joe Mac Phee
Swinging the compass
Gentleman,
Actually you can use a range to swing your compass and obtain a deviation table. If the compass is mounted such that you can take bearings over it, say on a pedestal or in my case on a bracket on the mizzem mast, you can take bearings on the range at different headings. For each heading (say the cardinal points, N,E,S,W), you take a compass bearing when the range is aligned. Ideally the bearing at each heading should be same as that measured on the chart (corrected for variation). Any difference is the deviation is for that heading. For best accuracy, the range should be on land based objects and not floating objects such as buoys.
Joe Mac Phee
S/V Iolanthe
CD-30 K
jvmacphee@aol.com
Actually you can use a range to swing your compass and obtain a deviation table. If the compass is mounted such that you can take bearings over it, say on a pedestal or in my case on a bracket on the mizzem mast, you can take bearings on the range at different headings. For each heading (say the cardinal points, N,E,S,W), you take a compass bearing when the range is aligned. Ideally the bearing at each heading should be same as that measured on the chart (corrected for variation). Any difference is the deviation is for that heading. For best accuracy, the range should be on land based objects and not floating objects such as buoys.
Joe Mac Phee
S/V Iolanthe
CD-30 K
jvmacphee@aol.com