NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Used Sextant Wanted
From: Dahlgren P
Date: 1998 Jan 12, 8:29 PM
From: Dahlgren P
Date: 1998 Jan 12, 8:29 PM
In a message dated 98-01-12 00:02:35 EST, you write: << Is there any significant difference taking a sight on the deck of a pitching 35 foot sailboat with a plastic sextant over a shiny metal one. I realize that on a stable surface the tolerances would be great but I would appreciate hearing from someone who has used both on small boats and the differences it made. thanks, Jim. >> I have used an old Davis (Mark 15 I think) and a new Astra IIIB, both from the beach and while sailing (nothing too rough, perhaps 3 to 4 foot swells). My most accurate shots from the beach actually were taken with the Davis, with a couple of intercepts of 0.5 miles or better. It's a little hard to pin down the accuracy of the shots from the boat, as the only GPS I own is the Davis (gray plastic sextant). You get a much higher rate of change in the index error on a plastic sextant as it equilibrates. Also, there is much more play in the gears. To some extent you can work around this by only adusting in one direction, which is good practice anyway. Certainly the optics of the scope on the Astra are far superior to the Davis. But, the bottom line is, with care you can get good shots with either one. Paul Dahlgren =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-= =-= TO UNSUBSCRIBE, send this message to majordomo@ronin.com: =-= =-= navigation =-= =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=