John and Jerry have been writing about boat performance and speed trials; (SNIP) >I found that my sense of which boat was fastest had no relation to the >actual timed data. I will never use a demo day trial to conclude that a >boat is fast. I believe that at 4 knots and below there is not a dime's >worth of difference in the efficiency of these boats, but I don't know how >to test this. This does not appear to be unusual. When developing the Stealth Canoe for the CCA we had top level (read Olympic medalists) test the new boat and then test their own personal boats. In every case they said the new boat was slower yet their times were always faster. Why? It turned out that the paddlers associated top speed with the noise and trim changes that accompanied their personal boats. Thus, if they did not experience the same changes and sensations they assumed they were not not going "fast". This strikes me as something fascinating. We sense so many things when paddling and appear to connect them as a perceived whole. Perhaps this explains why our perception of a specific aspect of paddling can be inaccurate - because we confuse sensations. Jerry wrote; > >These were flat water time trials, which do give you an idea of relative boat speed. However, I've found that in wind and waves, the whole thing changes. I've been on the water in moderately rough conditions many times when several Coasters were well out in front of the longer boats. Readers might be interested in why this might be so (this is a much simplified explanation. For those wanting the full thing I can refer them to the appropriate texts). Every boat has a natural pitching and heaving frequency. If the period of encounter with the waves approaches that of the boat's natural frequency then pitching and heaving increases and speed suffers. Since waves vary in length and boats vary in speed periods of encounter vary and shorter boats might be "faster" in waves that do not cause it problems but do cause the longer boat problems. If the period of encounter changes in favour of the longer boat then the longer boat can become "faster" again. I have actually been able to bring a boat to a complete stop when the waves were steep enough and the right length. As you can imagine, designing boats to suit sea conditions might be important. Designers of America's Cup yachts study the wave spectrums in the area where the race will be held and then adjust the design to provide the best match for the expected conditions. Those who have seen films of the British Challenger Sceptre bobbing about while Columbia charged ahead will have seen this at work. The effect of pitching and heaving may not always be obvious to sea kayakers so it can be a bit of shock when a "slower" boat pulls ahead. 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/ ***************************************************************************Received on Mon Oct 12 1998 - 05:32:44 PDT
This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:30:00 PDT