| Yes you can find higher pitched props but you don't want them. At 6 knots you are doing 594 feet per min. so with 12 inches of pitch and slippage at say 20% you are going to get about 450 RPM. Now with 10 inches of pitch and the same slippage gives you 572 RPM You want as much rpm as you can get to drive your altnator for two reasons to get your voltage up and to get amprage to charge your batteries. I'll also let you know all blade style wind turbines use a very fine pitched blade. Guess what, you need that too in the water at low speeds. Most people forget or don't know electric motors like to spin up to make their power, they also draw less power because they are not being lugged. Myself I would pitch the wheel so it would give me my 6 knots or my cruise speed at or near the motors peak RPM because it's going to use less wattage to do so. One of my big gripes is people treating traction motor like an IC engine when they set things up... mainly having the traction motor turning at the same RPM as and IC engine would be in it's app. They end up lugging the motor, burning brushes and commintator because of the higher amp draw as well as over heating the motor. Electric/traction motors are happy to spin at or near their peak RPM hour after hour for days. It's when you over load them at low RPM that hurts them, this is really true on a motor that you can change the brush timing on. femm --- On Sun, 10/2/11, Michael Mccomb <mccomb.michael@yahoo.com> wrote: |
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