NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Cel Nav!
From: George Huxtable
Date: 2004 Jul 27, 09:52 +0100
From: George Huxtable
Date: 2004 Jul 27, 09:52 +0100
This is a note, mainly to say how much I enjoyed Robert Gainer's piece of 18 July, under threadname "Cel Nav!", which he dismissed as "just some ramblings about sailing". If he has more such ramblings, I, for one, would be really interested in reading them. I thought the account of his rescue by "Hagen" showed a remarkable feat of seamanship by both parties: in meeting-up on the basis of astro observations, and then in the haulout, of both Robert himself AND his vessel! His story about mistaking the Moon, rising out of the mist, for a searchlight, rang true to me. After a long period without sleep, I have made exactly the same mistake, and like Robert, felt a complete fool about it afterwards. On another occasion, panic ensued from what seemed to be a rapidly approaching masthead light on a misty night, which turned out to be an aircraft's landing-light, as it made its approach to Jersey airport. Some, like me, get sufficient kicks out of sailing a small boat in continental-shelf waters to feel the need to go ocean cruising: but that doesn't diminish our respect for those, like Robert Gainer, that do. Just one aspect of his contribution had me puzzled, in which he said- " The mist on the Grand Banks meant that with my height of eye there was a large amount of time that no horizon was available to me. In fact on that boat my height (6 feet) of eye was so low that any kind of weather made it hard to get a shot." To me, those are circumstances (perhaps the only circumstances) in which the small-boat navigator has a positive ADVANTAGE over his counterpart in a big ship. I don't think I could put the matter better than Squire Lecky does, in his "Wrinkles", in which he says- ==================== "THE SEA HORIZON. Every seaman knows that by going aloft in clear weather his range od view is extended, and that on account of the Earth's curvature the visible horizon recedes from him the higher he goes. In like manner, by descendinf downwards towards the surface of the water, his range of view is lessened, and the horizon approaches him. Advantage can be taken of this to get observations in foggy weather. By sitting in the bottom of a small boat in smooth water, or on the lowest step of the accommodation ladder, the eye will be about two feet above the sea level, at which height the horizon is little more than a mile and a quarter distant, so that unless the fog is very dense, serviceable observations are quite possible. The writer, on three different occasions, when at anchor off the River Plate, during fog, has been enabled to ascertain the ship's position in the way described, and after verifying it by the lead, has proceeded up to Mone Video without seeing land..." He goes on to summarise- "In fine clear weather, take your observations from the highest convenient place, say the bridge... ...In thick or misty weather take your observations from as low a point as possible, and in all cases apply the correction for height of the eye corresponding to what it is known to be at the spot where the observaton was taken..." ================== It seems to me that the circumstances Lecky refers to are precisely the same as those that Robert Gainer was referring to on the Grand Banks. In which case, any difficulties he was experiencing in seeing a horizon from his low height-of-eye would have been far worse to a navigator on a larger vessel, observing from higher up. I wonder if he has any comments about that. I do recommend Lecky's "Wrinkles in Practical Navigation" (my edition being 1920, but the first was 1881) as being full of commonsense and real homespun wisdom, well written. making for easy reading. He covers well the overlap period between sail and steam. George. ================================================================ contact George Huxtable by email at george@huxtable.u-net.com, by phone at 01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK. ================================================================