
03-11-2008, 01:58 PM
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Join Date: Aug 2007
Location: I presenbtly live in Covington , LA.
Posts: 673
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High Water & Flankers
Greetings From New Orleans ,
Since my last posting a number of thoughts have also come to mind about the nature and different aspects of navigating ships and towboats in a high water environment . One element of this is: How do these large tows with any where from twenty to thirty plus barges manage to maneuver around some of the tight and swift turns we have on the lower Mississippi River . As was mentioned with the Str. Sprague , due to the size of her tows , much of the time she was going astern ( in reverse on her engine and paddlewheel ) inorder to maneuver and back around with limited technology and ability around these points anbd bends we have on the Lower Mississippi . As far as the modern day towboat is concerned , these boats now have a number of factors going for them that the Str. Sprague simply did not . First of all , the modern day towboat has anywhere from 5,000 t0 10,500 hp , two to three separate diesel engines and is equiped with flanking rudders which are located in front of the towboats propellers so that when the engines and propellers are going astern ( in reverse ) by maneuvering the flanking rudders from one direction to another the towboat is able to literally steer the stern of the vessel from one side to the other . Another tool the modern day towboat has are Flanking Buoys that are secured to the out side corners of the outside stern barges . The towboat pilots uses these buoys to literally determine his sternway or headway through the water . For example , when the Flanking Buoys are leading aft and are being pulled through the water , well obvisouly the towboat has head way or forward motion through the water . Then when the Flanking Buoys are leading forward and in front of the corners of the stern barges , well the towboat is going astern and has sternway through the water . Now when the Flanking Buoys are floating right off the corners of the stern barges , the towboat has neither headway or sternway and is literally going at what we refer to as current speed . When one of these large line towboats goes into a flanking maneuver around a point or into a landing , the towboat pilot will pay close attention to his Flanking Buoys so as to get an accurate idea as to what his vessel is doing in relation to his speed through the water . Ideally , the towboat pilot will slow the towboat to get down to Flanking Speed so as to literally move the Pivot Point of the tow from about one-third from the head of the tow to about one third from the stern of the tow , and thus almost become stationary in the water , so as to allow the current of the river to push around the head of his tow . This whole process can take up to thirty precious minutes to complete and when coming down on a large tow in a flanking maneuver and there is no room to pass around this flanking tow , it becomes very nerve raking .
Smoothe Sailing !
Ted Davisson
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