NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Paul Dolkas
Date: 2015 Apr 1, 12:10 -0700
Francis-
The Suunto is fluid damped - most good backpacker’s compasses are. I also have a Ranger (w/o a mirror), and it is damped as well. Normally you can’t see it, but at altitude you sometimes see a small bubble, due to the reduced pressure. Not sure if nautical compasses have “thicker” damping than their landlocked cousins, but I wouldn’t be surprised.
Of course, being hand held, they don’t have gimbals.
I’ve mentioned it before on previous posts, but I’ve added a dot to the center of the pivot, so I can line it up with the crosshair in the mirror when taking a sight. Eliminates any mis-alignment, and you can usually get within a degree accuracy. Can’t for the life of me figure out why it doesn’t come so equipped.
Paul Dolkas
From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Francis Upchurch
Sent: Wednesday, April 01, 2015 6:12 AM
To: paul@dolkas.net
Subject: [NavList] Re: Determing the bearing off a celestial object.
Thanks Paul,
That looks good and easy.
I use my old RDF as my prefered handbearing compass because it it very good, damped in fluid and gimbled against small changes in horizonal position/ocean swell etc. Can you get that with an undamped back-packer's compass? Not sure. Do you know of any fluid damped, accurate handbearing compass with that sort of mirror?
By the way, for sun Az, I have the compass at waist level and look down onto the mirror, the angle of which can easily be adjusted with a thumb to line up the reflection against the verticle, perpendicular line. I never aim directly at the sun.
Interestingly, I found by chance, last year, with new batteries, my 1980s RDF still works perfectly and I stumbled on several nearby "non directional beacons" (NDB) which give morse signals in the 250-400KHz range and with 3 with adequate spread of Az, I can get a reasonable fix, albeit with a fairly large "cocked hat". I shall try these at sea once I'm back in the water in May. Not sure how much longer the airports will continue broadcasting these NDBs (Gary may know?). I guess this is off topic (topic would be RDF/NDBs?).
Best wishes
Francis
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