Grand Traverse Bay at Hull Speed

Today we are heading up the deep and wide East Bay of Grand Traverse Bay, on the way to Leland again. Leelenau Peninsula is two miles to port, Mission Peninsula is two miles to starboard, the sun is warming the air, and seas are flat. A beautiful day on the water!

The past few travel days I have been experimenting with slow-cruising. R&R has a “planing hull” that partially rises above the water at higher speeds, but when moving at slower speeds acts like a “displacement hull” of the sort seen on sailboats and trawlers. R&R’s “hull speed” is the highest speed she can travel before rising up on plane. For numbers nerds, the hull speed (in knots) formula is 1.34 times the square root of the boat’s length at waterline (lwl). Assuming a 46 foot lwl, R&R’s hull speed is 1.34 x 6.7823, or 9.09 knots, or 10.46 miles per hour.

To get more practical, R&R consumes 8 gallons per hour at hull speed, and 25 gallons per hour at our typical fast cruising speed of 18 mph. With diesel fuel at six dollars per gallon and no need to get anywhere quickly, I am learning to like hull speed!

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