NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Taffrail log and an alternative
From: Arthur Pearson
Date: 2002 Jun 17, 21:18 -0400
From: Arthur Pearson
Date: 2002 Jun 17, 21:18 -0400
Trevor, Celestaire lists small taffrail-style log in their catalogue (and website at http://www.celestaire.com/catalog/products/3801.html). It is battery powered with an LCD display and a wire to trail the impeller and the literature indicates it reads out both speed and distance run. I have not purchased one but I would if I were planning passages of more than half a day out of sight of land. For bay crossings in the fog of Maine and Nova Scotia, a simple 30 foot chip log allows one to measure speed often enough and accurately enough to keep an accurate DR for several hours. Simply tie a bit of wood (weighted on one edge to be traditional and to minimize wind drift) on a length of light line, drop the chip overboard and time the number of seconds it takes for 30 feet of line to run out. Divide 18 by the number of seconds to get nautical miles per hour, so 6 seconds indicates 3 knots. I measure speed and plot a DR every 15 minutes. Any inaccuracy in speed measurement is less important that whatever allowance one makes for current and lee way. This is all I have had on dozens of trips Downeast and back in Maine and combined with a good ear and a good nose you should be fine (keep the engine off so you can hear surf, gulls, barking dogs, etc.). I join Trevor in his enthusiasm for traditional navigation other than celestial. While I still aspire to get my lunars to within 3 minutes of truth (still working on them thanks to encouragement found here), most of my sea time has been spent along the coast and I would love to swap insights on traditional piloting with list members. Anyone doubled an angle off the bow recently? Regards, Arthur -----Original Message----- From: Navigation Mailing List [mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM] On Behalf Of Trevor J. Kenchington Sent: Friday, June 14, 2002 3:58 PM To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM Subject: Re: sextant use Ed Falk wrote: > Maybe we should buy up all those sextants before the home decorators get > them. > > Does Southwest Instrument Company have any kind of web site? I couldn't > find one. No answer to offer on that but I did chance to find "Robert E. White Instruments Inc." of Boston at www.robertwhite.com Besides selling assorted new navigational and meteorological instruments, they recondition and sell used sextants. That can't be good for the business of the few remaining manufacturers but it does keep some fine instruments in use. For those whose interest in non-electronic navigation extends beyond celestial, Robert White also offers taffrail logs (Walker Knotmaster) and his "Nantucket Sounder" -- a nice hand "lead", though moulded in bronze. The latter is calibrated in fathoms (of course!) but the leadline is marked only by overhand knots at fathom intervals. Are we so far from a time when every seaman knew from birth that seven fathoms was red wool bunting while eight was a "deep" with no mark on the line? Does anyone know of other sources of working taffrail logs (including the spare impellers and lines which are inevitably needed sooner or later)? Off this shore, navigating in fog can't always be avoided and I'd like to know my distance run without resorting to electronics. Trevor Kenchington -- Trevor J. Kenchington PhD Gadus@iStar.ca Gadus Associates, Office(902) 889-9250 R.R.#1, Musquodoboit Harbour, Fax (902) 889-9251 Nova Scotia B0J 2L0, CANADA Home (902) 889-3555 Science Serving the Fisheries http://home.istar.ca/~gadus