NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: navigation by soundings.
From: Hewitt Schlereth
Date: 2009 Dec 21, 10:25 -0400
From: Hewitt Schlereth
Date: 2009 Dec 21, 10:25 -0400
Wonderful story. Great catch, George. And a Merry Christmas to you. -Hewitt On 12/21/09, George Huxtablewrote: > I will copy below a short extract from a piece that took my fancy in the > recent edition of The Journal of Navigation (vol 63 No1, January 2010), in > case it appeals to other navlist members. > It explains itself pretty well. Lowestoft is the most Easterly port on the > North Sea coast of England. An "armed lead", has a tallow or lard smeared > into a dimple under the lead so that it picks up a sample of the bottom. > > George. > > contact George Huxtable, at george@hux.me.uk > or at +44 1865 820222 (from UK, 01865 820222) > or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. > > ============================== > > Heaving The Lead > > Lt Cdr R W Cooper RN > > 2. BOYHOOD BACKGROUND. My experience of the practice of heaving the lead and > navigation goes back to 1937. My father was a North Sea fishing skipper and > I was the eight year old son who was obsessed with navigation. My bedtime > reading was Tait's Home Trade Guide, and I knew the Colregs, Morse code and > flag meanings off by heart. That year I was allowed for the first time to go > on a trawling trip with my father. > > Navigation at that time consisted almost entirely of sounding by armed lead. > The ship would be stopped and the 16-pound lead cast. The depth was noted, > and the state of bottom examined closely, and tasted by the skipper and > mate. I tasted it too. It was foul. This was done several times at hourly > intervals until suddenly, and for no good reason that I could discern, the > trawl was shot with the traditional order " Shoot the nets in the name of > the > Lord. " > > Soundings were taken at half-hourly intervals while trawling. And then after > hauling, the whole ritual was repeated. We had been trawling on a NNW > course, and before shooting again, we had moved some six miles to the > westward. This procedure was repeated several times until my father decided > to return to the home port of Lowestoft. No attempt had been made to fix the > position during the 72 hours. It seems that the bottom of the North Sea has > a fan-shaped pattern of low ridges which do not appear on navigational > charts. It is in the valleys between these ridges that the best flat-fish > are found. It is the fan-shaped nature of the ridges that make them ideal > for navigation, for the distance between the ridges gives the latitude > accurately enough. > > As the trawl was hove in on the derrick out at sea, my father himself cast > the lead, tasted it, and then ordered something like west-south-west and a > half west and off we steamed. The lead was cast at hourly intervals without > stopping the ship. It was swung overhead three times before being slipped > and only the depth noticed. Perhaps the course would have been corrected by > half a point. Otherwise we went straight at the Holm buoy. > > Note that the chart was never consulted. My father's collection of blue-back > charts was kept tightly rolled in black japanned-cases closed with a > padlock. Only he (and I) looked at them. They had originally been his > grandfather's and were never used for navigation. Certain sea areas were > covered with minute marks and symbols entered at the end of each trip by > mapping pen. They represented details of catches and abnormalities of the > seabed. > > > -- > NavList message boards: www.fer3.com/arc > Or post by email to: NavList@fer3.com > To , email NavList+@fer3.com -- NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList+@fer3.com