Thursday, August 1, 2013

NZ to Rarotonga: The Sequel: Going West to go East

For the past three days, Silhouette has been careening along on a beam reach, at a speed of 6-7 knots. It has been a challenge to keep the boat on course in the big beam swell stirred up by steady 16-20 (gusting to 30) knot winds. Life below has not been as comfortable as we rock and roll in the big beam sea or get slammed in the hull by waves, and Patrick and I are both experiencing sleep debt.

The wind has been QUITE gusty, and we have had to change sail configuration often as the wind rises and falls.

Tonight, for example, we are back on a beat. One minute, we are racing along at 7.9 knots of boat speed in wind gusts of 21 to 25 knots under only a stays'l and a double-reefed main; the next, we are doing only 2.8 knots with the same configuration in a fourteen knot lull.

The reason we are back on a beat is because the wind has begun to shift to the east in association with a low developing northwest of us. As the anticyclonic winds rotate around, they will eventually become head winds from the northeast, preventing our progress towards Rarotonga. At that time, Silhouette will head northwest until the wind changes to a favorable direction, before tacking back towards our goal of Rarotonga. As of this writing, we have 505 nm to go to Rarotonga; but instead of taking four or five days, it will probably take close to a full week due to this detour. Between the two detours we have made on this passage, we will have added a significant amount of mileage to an 1800-mile passage and turned a two-week passage into an almost three-week one.

For those of you at home who are non-sailors, it might be fun to see what I'm talking about by clicking on the "Passage Weather" link to the right. If you choose the wind forecast for the South Pacific through the various tabs located on the web site, you should be able to see the low developing west of Rarotonga. We can't see it out here because we only request weather files for a much smaller area over the radio, but the weather router we're using on this voyage can see the data back on land.

Lows show up as rotational objects with red, orange, and yellow colors. If they're really nasty, they have some purple colors. The colors designate the wind strength. Click the "animate" button at the bottom to watch the low move over a period of several days.

The wind symbols look like arrows with quills on the end but no tips. For normal people, the quills on the arrows face the direction the wind is coming from; but for sailors and meteorologists, the straight part of the arrow designates the direction the wind is coming from. (I have been a normal person longer than I've been a sailor, so to me, the straight part of the arrow points in the direction the wind is going.) Imagine the wind as bow, casting the arrow in the direction of its imaginary tip. For me, this has been especially confusing because the Windex (the wind direction indicator at the top of a mast) has an arrow whose tip points in the direction the wind is coming from, not where it's going to. Upon reflection, the meteorological symbols make more sense and should be more intuitive. The number and length of quills on the arrows designate the wind strength.

Hang on with Silhouette on her wild ride as she goes west to go east!

_____
Posted from sea via Ham Radio.

2 comments:

  1. Thank you for the Passage Weather Link It is very useful.

    ReplyDelete

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