NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Silico Sea 26 set, drift, and leeway
From: Bill B
Date: 2004 Jul 5, 17:40 -0500
From: Bill B
Date: 2004 Jul 5, 17:40 -0500
>> "Regarding SS 26 could I impose on you to work the problem?" > > Can remember from doing them some time ago that the Red Sea passages had a > few inconsistancies. > Agree with official answers for Q:1, and with date/time for Q:2. But for the > DR there seems to be some confusion, with the distance covered consistant > with the SMG of 12.8k but the course, 126.4dT, is the course given before > the current effect is factored in. Peter Corresponded with Mike outside the list as it included attached diagrams. I questioned what type of keel she has. Leeway tables for Beaufort 4 on something between a run and broad reach could range from negligible to 2 degrees. Best guess would be between 1/2 and 1 degree depending on keel and old rollers vs. new mashed potatoes. Also wonder if they factor in wind-induced surface currents. The Annapolis Book of Seamanship would suggest an additional .25 knot current for Beafort 4 running at a 45 degree angle to the right of the direction the wind is blowing. Since the wind is out of 310, it is toward 130. Add 45 to that and you wind up with 175. Almost parallel to the stated 5 knot current and in the same direction so almost 5.25 knots. With that and leeway, speed over ground would be 13 knots. With wind induced current, set, drift, and leeway factored in speed-over-ground would be about 13 knots and COG with 1 degree leeway would be approx. 146 degrees. Bill