17/11/2007 | by Oceangybe
Words by Hugh
Latitude: 19 degrees, 24.4′ South
Longitude: 156 degrees, 19.3′ West
Lest there be some confusion about the conditions we’ve experienced thus far on the crossing from Bora Bora to Rarotonga, let me draw your attention to the phrase ‘On windless night’ in Ryan’s last blog entry. True, to our immense irritation, we’ve motored through much of the past 3 nights. However, during the day Khulula has had some of her best spinnaker runs yet. Let me explain.
As predicted, the winds have been very light. How light? 4 – 6 knots during the night. What we’ve discovered is that about 6 knots of wind is the threshold for Khulula when sailing downwind. With less than that amount of wind we simply can’t get moving with any meaningful speed. The sails might fill for a few moments but when the boat is rocked by a swell, the air is lost, we slow down and then stall.
But there has been one blessing in the form of the ‘diurnal effect’. This is the phenomenon that causes winds to increase during the day due to heating of the earth’s surface by the sun. It is more pronounced near land, but still occurs out here in the middle of the pacific. So on the past 3 mornings, sometime between 8 and 9 am as we’re enjoy coffee brewed by Brys, the gentle puffs on our cheeks get every so slightly stronger. This is our cue to scramble on deck to get the spinnaker (downwind sail) ready to fly.
When the wind builds ever so slightly, maintaining between 6 and 8 knots, we hit a sweet spot; Khulula starts gliding through the water and carries speed over the swells. It is incredible really, because with this increase of 2 to 3 knots of wind, our boat speed goes from virtually nothing, to 5 knots! When the gusts reach 10 knots, we have been able to 7 knots with the right wind angle and swell direction.
So the past 3 mornings the diurnal effect has been like clockwork; around 9am the wind builds to 7 – 10 knots, the ‘chute’ goes up, we have 8 – 10 hours of incredible downwind cruising, and around 4 o’clock the wind gradually dies back down and we’re left rolling in the swells without the help of the ‘iron wind’.
Oh, and another key discovery was made this morning. The spinnaker pole is the perfect length to support Ryan’s hammock. I spent a good part of the afternoon stretched out in the hammock reading and watching the spinnaker fly!