Testing Cape Mendocino

Jumping Porpoise

We are just getting squared away to start surfing off Cape Mendocino when a pod of porpoise come by to share the fun. Three of them leap from the face of a wave in formation, surfing down the steep wave front with Wind Horse. A first for us in 35 years of cruising.

Wind Horse RPM and EGT gauges

We’re out here looking for a promised gale, testing Wind Horse with and without stabilizers, at various speeds and wave angles, and different displacements. We have lots of miles in steep seas, but would like more data in stretched out waves.

We are running right now at 1850 RPM, nominally 10.5 knots in smooth water. Exhaust gas temperature, shown on the lower meters, is an indicator of how much work the engines are doing. With wind and waves behind us, EGT is down 10 to 15% from normal.

We begin our tests at close to full load. Water tanks are filled (with 1900 gallons of fresh water) while we are a little under half on fuel. Once we do the first series of tests we’ll pump most of the fresh water overboard, dropping us to half load.

Cape Mendocino radar image

The following photos were taken just off Cape Mendocino, one of the tougher stretches of water on the Pacific Coast.


“SPD” represents the impeller log, while SOG is the GPS speed. We are seeing these types of speeds several times a minute, with top speed (unphotographed) of 22 knots. Average speed right now is 13 knots.


This is the view looking aft from the flying bridge. Photos typically compress wave size, but this will give you a feel for the waves we are surfing. The buoy reports say these are 13 feet (4m) at a 10-second interval.


The seas are steeper than we would like. They keep our speed down as within a few seconds of starting to surf we run into the back of the wave ahead. Bigger waves with more fetch would allow longer, faster rides.


These are the WH Autopilot controls. This is as close to the pilot being turned off as you can get. Gain, which controls the amount of rudder input, is turned way down. The rudder is turning just plus/minus 5 degrees. Very little effort is required to keep Wind Horse tracking straight down the waves.

After half an hour of surfing fun it is time for more scientific experiments. With counters clear of loose gear, safety lines in place, and wearing our harnesses, we turn off the stabilizers, and then check how Wind Horse performs at various angles to the waves. We are rolling plus or minus 15 degrees, with a fairly snappy motion. Compared to what we experience with the stabilizers turned on, this feels unpleasant. But if we were forced to cross an ocean without stabilizers it would be feasible. We’d just have to hang on a lot more carefully and wear our seat belts when sleeping.

If these conditions were to continue down the coast, the waves would eventually stretch out and build in height – just what we want. But contrary to NOAA’s promise, the breeze winds down from the north. And then comes in from the south – right on our nose.

Maybe next time we’ll find those BIG waves.

Posted by Steve Dashew  (September 8, 2007)

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