The connection between my backrest and kayak has three possible locations each of which are approximately 1" apart. At the moment the backrest is mounted to the middle adjustment. What should I expect the response of my kayak to be if I moved 1" forward or 1" backward ? grant Grant A. Thompson Summerland, BC *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
Grant wrote; - >The connection between my backrest and kayak has three possible locations >each of which are approximately 1" apart. At the moment the backrest is >mounted to the middle adjustment. What should I expect the response of my >kayak to be if I moved 1" forward or 1" backward ? Unless the seat is moved at the same time the center of gravity should not alter much and, as a result the boat will not be affected much. The biggest change will be in your comfort level. To find out how much change there will be ask your boat builder how much moment is required to change the trim one inch. For an average male moving the upper torso two inches should only produce about 15 - 20 foot pounds of moment. Typical sea kayaks will need about 70 - 80 foot pounds to alter the trim one inch. My experience is that this makes little difference except when surfing. Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
In a message dated 98-10-07 07:40:59 EDT, John Winters <735769_at_ican.net> writes: << To find out how much change there will be ask your boat builder how much moment is required to change the trim one inch. For an average male moving the upper torso two inches should only produce about 15 - 20 foot pounds of moment. Typical sea kayaks will need about 70 - 80 foot pounds to alter the trim one inch. My experience is that this makes little difference except when surfing. >> I'm not even <thinking> of challenging John on matters-hydraulic, but when it comes to matters-visual, I recently watched a paddler in a Mariner reach down into the cockpit to slide his seat forward and aft and noted some significant hull attitude change --- and hull shape, too. ("Significant" appeared to be more than an inch or two.) What am I missing here? That seat can't slide more than a few inches either side of "neutral" --- wherever that is --- but the hull definitely moved in concert, and moved enough to be noticable visually and, for the paddler, presented a fairly significant set of performance parameter changes. On a personal basis, I'm planning to build a CLC North Bay over the winter, and would really like to know if I have more freedom in the longtitudinal placement of the seat pan than I thought I did. Jack Martin *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
Joq wrote; (SNIP) >I'm not even <thinking> of challenging John on matters-hydraulic, but when it >comes to matters-visual, I recently watched a paddler in a Mariner reach down >into the cockpit to slide his seat forward and aft and noted some significant >hull attitude change --- and hull shape, too. ("Significant" appeared to be >more than an inch or two.) What am I missing here? That seat can't slide >more than a few inches either side of "neutral" --- wherever that is --- but >the hull definitely moved in concert, and moved enough to be noticable >visually and, for the paddler, presented a fairly significant set of >performance parameter changes. The difference would be that the paddler in the Mariner moved the entire seat. I think the original question concerned just moving the seat back which would only affect ones posture. Moving the seat moves the entire body not just the upper torso that more or less poivots about the body's CG. Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
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