Notes for 5/8/08 talk on wind.
Peter asked me to give a short talk on wind, probably because he wanted some entertainment and I was cheaper than a band.
I’ll break this talk into two parts. One about wind in the bay and another about wind offshore since some of you will be sailing to Key West next week.
You should also remember two things. One, the wind is fickle and two, I might be wrong. You can be sure that sometimes I’ll be wrong.
In the bay, the wind is determined by a combination of weather system wind and sea breeze wind. The weather system wind is probably whatever was blowing the night before or in the early morning.
Transitions between weather system and sea breeze can be guessed at with better than 50-50 accuracy.
If the wind is out of the east in the morning and is not strong enough to last through the afternoon and the land is going to heat up more than the Gulf temperature, the direction will switch around to the western hemisphere. If the wind starts out south of east it will swing right. If it starts out north of ENE it should swing left. It may also completely die before it fills in from the west. If it does this, there shouldn’t be a race until it comes from the west.
This information should only be used to get a general idea of where to look for a persistent shift. Usually the breeze will work its’ way around in an oscillating manner. That means there will be shifts back to the direction from where it began before it once again swings further to the direction toward which it is working. Courses on Sarasota Bay are short enough so that a 4 minute shift from the left, even if the wind is generally moving right, will give a boat enough time to get across the fleet and jump out to a lead.
Therefore, in the bay, you are going to gain almost all the time if you are in phase. This means sailing on the lifted tack and tacking on the headers. Use your determination of which way the wind is swinging to favor the side you are going to work.
It’s also important to look up the course and try to determine from where and with what pressure the wind is coming in. Often it will alternate from side to side. You can use other boats up the course and black ripples moving on the water to give you some clues.
This is critical when the easterly is strong enough to hold on throughout the day. As the day goes on and the land heats up, the easterly will oscillate more and more radically. 40° shifts with enormous pressure differences are likely. Getting to the next big puff shift will launch the first boat there. Put a couple of them together and it’s a horizon job.
Southerlies are tough. Often there is better pressure on the left where the wind has a longer run to flow over the bay. However, as you get close to E, the pressure diminishes behind City Island and sharp righties can filter in from New Pass. Keep your head out of the boat and look for those ripples building across the water.
Once the wind goes around to the west, the oscillations should be less radical but they will still be there. Staying in phase is important.
If the wind comes in southwest you should be going to F, stay in phase but look for lefty puffs coming from the vicinity of E.
If the wind is from the west, stay in phase but keep a look out for the wind to go further right especially if it shows signs of building. Absent weather system change, if the sea breeze is going to ripen into full blown 15-18 knot conditions it will be from 310°. If this is the case, the wind will still oscillate as it works it’s way from 270 to 310. There will be a few lefties but you had better be generally working right. If the breeze is not definitely building, be sure to look for puffs from the mangroves to the left of F
The classic 310 sea breeze direction has some local idiosyncrasies on Sarasota Bay. Leaving from I, there will often be lefties over toward Longboat early. Go there carefully because there is great danger from boats on the right. From just below H all the way up, righties often blow in from the Bayshore Gardens direction. I almost always approach H, 15, 16, and J from the right. J is the trickiest of these because it often gets very shifty with large velocity differentials in the cove off the Moorings entrance.
Friday nights are a little different because instead of transitioning from weather system to sea breeze direction, the wind is going from sea breeze to weather system. Sailing on Quantum Leap years ago, with Dave Olson and John Steele, we came up with a mantra we lived by, “Right at night”. It worked great that whole year. The wind was almost always 310 and brisk that whole year. Since then I’ve added some qualifications to that rule.
As summer progresses, the chance of squalls and thunderstorms increases. Clouds are signs of wind and it’s usually beneficial to get to them first. Around 1970 Cindy’s younger brother was getting ready to go to the Sunfish North Americans on Lake Erie. He was a bay sailor and had never sailed on a lake. So her father advised him, “If you see clouds building, head for them”. So he’s out on the lake and sees clouds building and he heads for them. Sure enough, out of 100 boats, he’s the first boat…………… …………………………………………………………………………………………...
to get flattened as a 60 knot squall rolled through and the last one to limp back to shore after the race was blown off.
On Friday nights, squall wind will usually come out the east sector. You should try to be the first one to it but keep an eye on how much wind it’s packing and be ready to compensate accordingly. Sometimes the best compensation might be to lower your sails and heave to.
Off shore going to Key West, you are sailing from a sea breeze or weather system environment to a trade wind environment. The boundary is usually somewhere around Florida Bay.
If you can make ground to the east, I think you should do so at least until Smith Shoal bears at least 190 or 200. The tradewind is often SE in May and you will need to be far enough east so you don’t have to tack to get to NW Channel entrance.
You may very well encounter squalls along the way. The wind comes out of the clouds and spreads across the water. There is wind on the sides of the squall. There is no wind underneath. Try to sail along the sides not underneath. Pay attention to what direction and how fast the clouds are moving to get an idea of how to by pass the center. You have to react early as the clouds are usually moving much faster than a sailboat.
Even if the clouds are not threatening with a lot of wind, there will be more wind in scattered puffy cloud areas than in areas of clear sky. Work toward those clouds.
The transition zone where the wind is light and fluky is often reached at night when the crews are tired. A crew that is alert, can react to wind changes quickly and keep the boat moving in the early morning hours will make big gains on a crew that is sleeping through this trying period.
If you find yourself in area of light to non existent wind, even though you are off shore in a long race, gains can be made by keeping a sharp look out and sailing to scattered patches of breeze. Every little puff helps and if when that one last puff gets you to the filled in breeze before another boat, you are going to gain an amount of time equal to how much you beat him to the breeze.
To summarize, in the bay, stay in phase, keep a lookout for pressure and shifts, work toward them. Pay particular attention to and favor the areas you expect the changes to come from.
Off shore, keep up the VMG. Don’t sail hard close hauled nor deep downwind. Keep a look out for clouds and changing weather conditions. Be ready at all times (especially late at night) to quickly react to changes.
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