VT con mare formato

[kermit]

Detto questo e tornando in argomento per Leandro ed altri interessati allego un documento che tra i tanti ho raccolto e che nella sua sintesi e chiarezza mi piace molto.
E' in inglese e se qualcuno lo vorrà tradurre per il bene di ADV sarebbe cosa gradita, io lo leggo bene ma una traduzione elegante e corretta scritta me la vorrei risparmiare.
Buona lettura

Boat Handling in Velocity Headers

Note: In 2001, Mark Spicknall made a presentation to the Lansing Sailing Club titled 'Winning on Lakes'. One of the topics covered in this presentation was 'Velocity Headers'. In August and September of 2003, LSC's Pat Dolan had an email exchange with Mark Spicknall exploring this topic in a little more detail. The information here is derived from the original presentation and the email exchange and formatted in the form of a conversation in an attempt to make the information more understandable.

Pat: When you spoke to members of the Lansing Sailing Club In 2001 about velocity headers going upwind, you advocated continuing to sail your course until boat speed bleeds off and the apparent wind settles in again.

Mark: Yes. The goal is to always sail at or above the target boatspeed for the prevailing true windspeed and in a direction that gets you to the mark the fastest.

Pat: Does the amount of wind have any impact on this?

Mark: My experience is that it is best to continue sailing your course with the sail luffing until boat speed drops to match the new wind speed in all wind conditions as long as the water is flat.
Pat: What if there is chop?

Mark: In chop, your boatspeed will obviously drop alot more quickly and it is critical to not let the boat fall below target for the new windspeed.. Also, as the wind goes lighter in chop the target true wind angles are usually somewhat wider than normal in order to maintain the boat's target speed. So in chop, you probably want to fall off some, but less than you might think.

Pat: Does the type of boat you are sailing make a difference?

Mark: Lighter boats like a Laser will obviously be more sensitive to this situation because of their lack of momentum. A heavier boat like a J24 will be a little more forgiving. The idea is to keep the boat moving at or above its target boatspeed for the prevailing true windspeed.

Pat: Most of us are dinghy sailors. Any suggestions on technique?

Mark: For big boats you have your established targets and instruments to work with. For small boats this is more of a seat-of-the-pants thing. Hopefully, as a Lightning or other dinghy sailor gains experience, they will begin to have a good sense of how fast the boat should be going for various wind speeds. When the windspeed drops, you keep going with the jib luffing a bit and let the boatspeed bleed down to what you think the speed should be for the lower wind and slowly bear off only as necessary to bottom out at that target.

Pat: Now let's talk about downwind.

Mark: The idea is generally the same - sail the boat at its targets for the prevailing true windspeed. As the lull hits, you want to use the excess speed left over from the bigger breeze to continue to work downwind as long as possible. The apparent wind will go forward for awhile, and it will likely be necessary to ease the pole forward and to trim the chute to keep it from collapsing. Let the speed drop toward the new target while at the same time beginning to head up gradually and as necessary so that the boat's speed will bottom out at the new target.

Pat: Eventually you need to head up and sail a higher angle.

Mark: Right. Depending on the range of wind this can result in a very small or very large change in sailing angle. If the wind drops from 18 to 12, only a small angle adjustment will be required. But if the wind drops from 10 to 4, you might have to eventually head up 25-35 degrees as the boatspeed dies to assure adequate boatspeed in the heart of the lull. This will result in a much tighter apparent wind angle.

Pat: Always continuing to push down as long as possible until the boat speed decreases to match the new wind condition.

Mark: The trick is not to head up too quickly so as to utilize the excess boatspeed left over from the bigger breeze to work downwind as much as possible, while at the same time heading up quickly enough to keep the boatspeed at or above the new target. In chop you might have to come up a bit more quickly to maintain target.

Pat: Any special ideas for patchy conditions where you have wind one moment and then none for a while?

Mark: If the wind is obviously completely disappearing and you know the fleet will be just sitting and going nowhere for awhile, the trick is to use the remaining momentum to slowly turn toward and go directly at the mark. Just before the boat stops entirely, use the last little bit of momentum to angle the boat for where the wind will come from next (but not head to wind). Then when the wind comes back, you are at least that much closer to the mark and you are ready to take advantage of it. I've made 4-5 boatlengths at a time on competitors doing this little trick in patchy conditions.