sailing by the lee

A

ascella_dylan

New Member
Now I have been told that the reason behind sailing by the lee and kiting downwind is to reverse the airfow around the sail (ie the leach becomes the luff and vise versa) so i installed a reversed set of tickillers and a set of telltales on the mast sleave to test this theory but every time they start to show signs of life I proptly death roll into a 5 degree C lake ontario :eek: and I was wondering if anyone can conferm or deny this theory. I plan to build a little model and with the help of a fan test it in the warmth of my bath tub but until then i was wondering...

Dylan

Your madjesty there is no second :D 966.5 days to challenger vs allingy americas cup 2007
 
Yes, the airflow is reversed when sailing by the lee.
However you won't see much on telltales near the mast tube, as the flow is no longer attached at that point.

If you want to see the reverse flow, put a couple telltales about 12" from the edge of the leech, one on each side of the sail, up near the top batten. They will start to flow towards the luff when you are by the lee

How far out are you letting the boom out? You don't need to let it out much past 90 degrees to sail by the lee, you just need to turn the boat past dead downwind...
 
49208 said:
How far out are you letting the boom out? You don't need to let it out much past 90 degrees to sail by the lee, you just need to turn the boat past dead downwind...
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Yes! and just to add to that: you will reverse the airflow quicker by sheeting in (if you let out the boom more than 90 degrees the airflow will still by the usual way). I also find that sheeting in a bit gives more stability and prevents the deathroll. Maybe the rule is more boom out is more deathroll? Any other thoughts on that?
 
Gerard said:
Maybe the rule is more boom out is more deathroll? Any other thoughts on that?
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Anything that puts put enough of the sail past 90 degrees when running so that the force of the wind is acting to push the boat over to windward will cause it to heel/deathroll to windward. This includes letting the boom out past 90 degrees, or sailing with vang loose enough so that even though the boom is at 90 degrees or less, the upper part of the sail is twisted well beyond 90 degrees.

You counteract this by moving your weight away from the windward rail, towards the leeward side. It becomes a very fine balancing act....

You also want the daggerboard down more when sailing by the lee, again this helps to counteract the force pushing it over to windward somewhat, and also gives you a little feel of tracking thru the water as opposed to sliding... I usually only have mine up about 9"-12" when sailing by the lee...
 
If you are in the death rolls by the lee, you can try to save a capsize by pulling the tiller hard towards you and going more by the lee, you may end up gybing, this is better than swimming. Your instinct is to push the tiller away and head downwind, you will almost certainly go in!
Like the others said, boom not past 90, be ready to move about the boat with your body weight, and practice.
Good luck
 
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