A few days ago I was checking the weather forecast for that day on San Francisco Bay.\u00a0 It was a pretty mild wind forecast for late August, winds from the SW at 15 with gusts to 25, however it got me thinking about what that really meant.<\/p>\n
Winds from the SW at 15 \u2026 wow \u2026 the perfect wind for sailing under an un-reefed main and full jib.\u00a0 But, what about those gust to 25?\u00a0 Here are a couple of things to keep in mind about wind in general and gusts in particular.<\/p>\n
First, the difference in the power of the wind is not just 10 knots (a 66% increase).\u00a0 The power of wind doesn’t increase in a straight line, it increases exponentially.\u00a0 25 knots of wind contains nearly 300% of the force of a 15 knot wind.\u00a0 That well balanced 15 knot sail plan is way over powered in 25 knots.<\/p>\n
The second thing to keep in mind is wind direction.\u00a0 Although this can be altered by the geography of the bay, in most cases, gusts come from the right of the wind’s true direction.\u00a0 In other words, that SW 15 wind may be gusting at 25 from the W.\u00a0 If you are on a port tack in the gusts your sails are probably \u201cunder trimmed\u201d based on the wind direction, which may be a good thing while you ride out the gust.\u00a0 On the other hand, if you are on a starboard tack, when the gust hits, you are over trimmed in 3 times more wind!\u00a0 No wonder things get a little hairy out there during gusts.\u00a0 One last thought regarding the starboard tack idea \u2026 what is going to happen if you are on a run before the gust overtakes you?\u00a0 At best, you will be sailing by the lee \u2026 at worst; the gust gets on the wrong side of the main sail, and WHAM!\u00a0 An accidental jibe in 25 knots can ruin an otherwise perfect day of sailing!<\/p>\n
So, here is the question.\u00a0 In those conditions, do you reef, or not?\u00a0 Unfortunately, the answer is not a simple yes or no.\u00a0 How many gusts are there?\u00a0 How long are they lasting?\u00a0 What is my tack and point of sail?\u00a0 I do know that I am more likely to reef if I’m on a starboard tack with the wind forward of the beam and less likely on a port tack or with the wind abaft the beam.\u00a0 I probably won’t worry too much about being on a run on a port tack, but will rarely go on a run on a starboard tack during gusty conditions.<\/p>\n
It basically boils down to this \u2026 if I find myself (or someone else on the boat) asking \u201cshould I reef?\u201d\u00a0 The answer is YES!!\u00a0 It’s very easy to shake it out later if I didn’t really need it.<\/p>\n","protected":false},"excerpt":{"rendered":"
A few days ago I was checking the weather forecast for that day on San Francisco Bay.\u00a0 It was a pretty mild wind forecast for late August, winds from the SW at 15 with gusts to 25, however it got … Continue reading