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Interesting Downwind

2K views 10 replies 6 participants last post by  albrazzi 
#1 ·
Light air DDW making 1.8 maybe 2 Kts our 155 was basically just hanging, to be expected. As a bigger Boat passed (38 ft) we noticed his head sail was more or less backwinded, it was like the Boat was going faster (just a little) than the sail. We slowed just a little by dropping the pole pulling the sail in, so the faster trim was to let it back just that little. Any suggestions on filling it up? Main in to funnel some air into head sail? We got a unique look into our trim from the other Boat.
 
#2 ·
Lots going on with turbulence around the sails going DDW, and sometimes the boat’s momentum can keep it moving faster than the air around it, so the sails backwind. The best options will depend upon the boat, rig, windspeed and direction. There are lots of variables. Racing in our Main & Jib fleet, we find it fastest to wing out our jib, even with the wind at about 10-15º off (in either direction) from DDW. We post a crew with a boathook to hold the sail out because it’s easier than rigging up the spinnaker pole. Heeling the boat to windward can help the jib hold its shape and improve the airflow over it, which can boost speed. Depending upon the angle of the wind and your boat, it could also be faster to improve airflow over the leeward side of the main (and reduce turbulence) by keeping the jib on the same side as the main, but still poling it out so as to increase the width of the slot. Try different things to see what works.
 
#3 · (Edited)
You were going DDW, but were NOT wing-and-wing?

Rig it wing-and-wing. Note that the tell tales on the main are actually reversed, with wind flowing from leach to luff, then dumping air in the jib. The main is not all the way out.



Other boats sail with the main all the way out.


Although this depends on the boat, in very light winds broad reaching is often faster.
 
#4 ·
Yes we were WoW and have done some exercises on this small 4 mi full course, and Gybeing was faster (over ground) but still crossed behind the Boat I was following, same with another racer. So yes I understand the choices, I always like to keep the Genoa by the lee for safety if 10-15 degrees off DDW, and yes its hard to steer and a LOT going on if the wind is up. Probably a unique situation where the bigger sail was back winded pretty much all the time on this leg, his and mine. PDQ, nice pictures, you learn a lot from pictures, if the water is throwing the Boat around sails unload and cycle, some the the Mains in your picture were doing as I describe but I suspect intermittently, but this case was very smooth water and back winded for quite a while.

And yes we have won races using the Boat hook to keep the slot open, it works! I will add tells on the luff curve this winter, all I have now is leech tells, I need more!

Thanks Guys
 
#6 ·
Personally I'm not a fan of sailing DDW, particularly in light wind, although if you must, then it is all about projected area, so wing on wing is the way to go.

The problem with sailing deep in light wind is that 100% of your boatspeed is subtracted from your apparent wind. The bubble you say in the bigger boat's headsail was caused by them "running over" their apparent wind. The boat was coasting on it's momentum as the wind dropped, causing their apparent wind to swing forward.

Often you are better off sailing hotter angles to get the boat moving faster, and then as your boatspeed increases your apparent wind will move forward, allowing you to start working back down.

Get your crew all sitting down on the low side to heel the boat as much as you can, that way, even if the wind can't lift the headsail fully, gravity will at least help it hang in a foil shape.

Sent from my SM-G960W using Tapatalk
 
#7 ·
I use a different approach on bigger courses, this one sort of precludes Gybeing and DDW just works where it might not on an open course. Not my favorite thing to do but we have won some good races where others dropped out. You have to finish to win, that's what I say:wink

Good suggestions here,, Thanks
 
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