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A Question Of Trim & Paddlewheels

 
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Old 09-23-2007, 05:42 PM
 
Join Date: Aug 2007
Location: I presenbtly live in Covington , LA.
Posts: 673
Default A Question Of Trim & Paddlewheels

Greetings From New Orleans ,
It has been a quenstion of mine I have pondered over the years from my early days on the Delta Queen to my present time on the sea going ships . Simply what is the relationship of a vessle's trim to speed , either it be headway or for that matter sternway ? Now for the uninformed , trim is in layman's terms , how the boat sits in the water , either down by the head ( the bow ) , down by the stern or simply even keeled . This question and issue first came into play when the Delta Queen was either in a so-called " race " with the Belle or we just had to make time , north bound in high water . Captain Wagner would order us to flood the Queen's forward peak tank supposdly to raise the stern and to lift the paddlwwheel futher out of the water . At the time , none of us had the courage or wherewithall to question Captain Wagner on either his motives or logic for doing this but this action planted the original seed in my mind , on why would sinking the bow futher into the water necessarily raise the stern ? Like a pivot point on a tow or a ship , is there a teeter-tooter effect with an undwewater fulcrum that moves fore and aft to effect the stern's draft ? Now haviing said that , just possibly Captain Wagner also instructed the engineers to burn out the stern fuel tanks and throw the beer machine into the river , which would reduce weight in the stern compartments , keep the engineers sober and then thus raise the stern and paddlewheel as well . Now , you have to ask yourself , what made the boat go faster with the wheel futher out of the water ? Did less water resistance translate into more revolutions by having the wheel futher out of the water or was it because there was less draft on the hull or both ?? The next thought that came to mind , was just possibly by sinking the bow deeper into the water and incerasing its draft , the bow would then have the same or nearly the same draft of the stern and placing the entire hull on a more even keel and then thus reduce the friction , drag and resistance of the stern and paddlewheel . Futhermore , and I realize this would be a monumental endeavor , but could the paddlewheel also be raised futher out of the water by removing the wheel's outside bucket boards and reduce weight and " carry over " , which by the way was a big issue on the Mississippi Queen . Now another isuue that comes into play is the effect that " Squat " has on a vessel . Essentially , squat takes palce when a vessesl has headway and usually the stern of the vessel sinks futher into the water . The problem with squat is there is both a speed and control loss . So , somewhere in this equation , you have all these varibles at play and to get the optome speed you must take all these factors into account . Along this same train of thought , I have always been impressed with the early naval archtitechts that designed and built the paddlewheels that were then placed on these steamboats . Did they learn from trial and error and did they have the courage to consult with the pilots and engineers to find just what worked better for either attaining maxium speed or for pushing and backing heavy tows for that day and age . I was always told that the best constructed wheel was a " square " by design and this was unfortunately Not taken into account with the Mississippi Queen' s wheel but Was taken into account with the Str. Natchez's wheel ! Just food for thought folks !!
Smoothe Sailing !
Ted Davisson
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Last edited by Ted Davisson; 09-23-2007 at 05:58 PM.
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