We now have construction of a new set of props underway.  These should address the upper speed limit we encountered testing the prototype out on the water.

The logic goes like this.

The motors we have installed top out at 1200 rpm.  The props we have on the motors have a 4″ pitch, great for low speed grunt, but not top end speed.

  • 1,200 x 4″ = 4,800″ per minute
  • 4,800″ per minute x 60 minutes = 288,000″ per hour
  • 288,000″ per hour / 12″ = 24,000′ per hour
  • 24,000′ per hour / 5280′ per statute mile = 4.54 statute miles per hour
  • 4.54 statute miles per hour / 1.15 = 3.95 Nautical miles per hour

With theses props on these motors we could expect to top out at 3.9 knots in the perfect world with no losses for slip, etc.  Given that we maintained just over a 3 knot average speed over the hour test going both with and into a strong wind, this proves out our gut instinct out on the water that our performance was limited by the low pitch props.

To prove this further we are engineering props with a 8″ pitch which should have a theoretical top speed of around 8 knots.  With all the real world factors such as slip allowed for this should get us to our desired top end of around 6 knots which is just under the boats calculated hull speed of 6.45 knots.

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