We just had the same thing happen last night.
We were in bed
at 9:00 or so (yeah... it was still light out.. ha ha) in one of the most calm nights you'd ever see. The water
was like glass (with 2-3 miles of fetch, if there was a wind
direction). There would be no hope of sailing. The wind
was basically non-existant. Not even a breeze.
As we turned out the lights, all of a sudden we heard wind in the rigging
like you'd hear in a tropical storm! No rain, no odd clouds, nothing. Just a gust of wind I estimate to be in the 40-50 knot
I was a little worried about our anchor
holding since in the calm, there is a great deal of slack in the chain, which would be taken up rather violently by the instant 40-50 knots we got.
As the wind started up, the boat was turned beam into the wind, since the slack in the anchor
chain had not all been taken up yet by the great push. As the wind increasted, we heeled maybe 10 degrees under bare poles (it's a big, strong boat). Once the anchor chain slack was taken up, the bow again comfortably pointed into the wind.
I got up to turn on my Palm Treo to check the weather
. By the time I could turn it on, the wind had already returned to calm.
We could make out some very strange, thin cloud or layer or something (it was dark) that passed us at about the time of the burst and stretched from horizon to horizon, moving in the same direction the wind came from.
We are about the same lattitude as Raven now, and in a similar body of water
to him (excet that it's salty). I wonder if there is some connection with that and these bursts. I had never experienced them before in my 20+ years at sea.