A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Cel Nav!
From: Robert Gainer
Date: 2004 Jul 27, 17:48 +0000
From: Robert Gainer
Date: 2004 Jul 27, 17:48 +0000
George, That sounds like an excellent book and I will have to see if I can find a copy in my neighborhood. I don�t know about other people�s experience but the height of eye on a small boat has always been a problem for me. If I get too high the motion of the boat is too much for me and if I get too low it�s difficult to keep the horizon in sight between the crests of the waves. It has been my experience that even on a calm day the swells offshore can be high enough so that if the mist or fog brings the edges of your world to within, lets say 2,500 feet then the horizon that you see may be the top of the swell or just the face of the swell but only part way up. If you have any waves at all on top of the swell the horizon is just unusable in fog. Of course this horizon that I think is false might be the �true� horizon and I just don�t recognize it as such. Because I am self-taught and until this group have not interacted much with other navigators I don�t always recognize what�s possible or practical. Although there is no opportunity to grab a shot, if you want to really go crazy finding the horizon, try sailing in a light snowfall. Your world is on a tilt and there is an illusion that you are always turning because of this. You can�t see very far, so the end of your world is only a few yards away. The snow will fall at an angle, the boat is at a different angle and you are standing at a third angle (you hope vertical). The waves will come by from yet another angle. You lose all sense of direction and cannot tell what�s vertical. If the wind is light enough the sails will hold a shape from the snow that is on them and if you glance away from the compass you will steer the boat in a circle. When you tack, the snow that is coating the mainsail falls off when the boat is upright and for some strange reason you are almost always standing under the sail when the snow drops off. By the way if you do sail in the snow it helps if you enjoy tea. At the end of the day I make a pot of hot water for tea and pour the leftovers on the cleats for the halyards to thaw the halyards out and get the sails down. I can�t recall a situation where I could shoot under the mist. I do recall several occasions where I could get above the fog. The one incident that stands out is a trip up the Elba River in Germany on a commercial ship. Early in the morning there was a very heavy fog on the river and I could not see anything of the shore at all from the main deck. I went up to the bridge and was astounded to see that the tops of the buildings along the rivers edge were above the fog and the ends of the ship were all but invisible from the bridge. As we went up the river it was as if we were flying just above the surface and the building were sitting on the tops of clouds. It was one of the most beautiful illusions I have ever seen. All the best, Robert Gainer >From: George Huxtable
>Reply-To: Navigation Mailing List >To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM >Subject: Re: Cel Nav! >Date: Tue, 27 Jul 2004 09:52:04 +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 email@example.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. >================================================================ _________________________________________________________________ Don�t just search. Find. Check out the new MSN Search! http://search.msn.click-url.com/go/onm00200636ave/direct/01/