NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: wind effected by tide?
From: JC Sutherland
Date: 2000 Feb 20, 19:48 EST
From: JC Sutherland
Date: 2000 Feb 20, 19:48 EST
Russel Forgive me if I have missed the point of your topic,but I dont have your original question. It seems to me that you maybe refering to a creation or modification of a wind by the tide. This is a normal occurrence. In the simplest example, suppose a boat is dead in the water with no sails or engine power, the tide itself will move the boat along. In turn this will generate an apparant wind over the deck in the opposite direction and with the same speed of the tide, this is sometimes known as the 'Tide wind'. To cut a long story short let me give an example of its application. Suppose you are heading for a destination which is to windward. In the absence of a tide either tack will serve as the initial course.but if a cross tide is flowing then the tack which puts the tide on the lee bow will allow the boat to point more up into wind and this in turn will shorten the distance to go. In the English channel this is a common way of crossing from one side to the other as the tide runs east/ west as the boat crosses north/ south. A six hour board, lee bowing the tide on one tack then changing tack on the change of tide will significantly reduce the time of crossing. You can easily loose a race if you don't get this right. It is the direction of the apparant wind over the deck of the boat that determines the best point of sail and the 'Tide wind' vectorally adding to or subtracting from the 'Meteorological wind' causes a modification to this direction . Obviously strong tides and light winds will give the greatest effect. Clive Sutherland.