Which is faster: heel or no heel?

C

computeroman2

Member
At a practice the other day, someone raised the question of which is faster in a laser downwind: Heeling or no heeling. The arguments are as follows.

In 420's, it's always fastest to have windward heel downwind to get the sail higher up in the air.

In Lasers, it's always fastest upwind to be completely flat, no exceptions.

Which tecnique applies here?
 
There are a couple things in play with a laser sailing DDW. Since it's a cat rigged boat the sail's force on the boat pushes it upwind naturally. So in order to counteract this you heel the boat to windward and use the curvature of the hull to keep a steady line downwind.. This way you won't have to use as much rudder downwind and loose speed because of it. Also one other "benifit" is that the wetted surface is reduced meaning less friction blah blah.
Of course this is really only some "guidelines" as swell, windspeed etc can greatly change the way you sail it.
 
Well, Ive found sailing the full rig downwind is noticeably quicker with a windward heel. Now, one thing is, the more you heel to windward, the faster you go , but the more unstable that little sucker becomes.

I like to keep it on the edge of disaster when sailing downwind, though Im experimenting with sailing by the lee for more stability and a bit more speed.

Runs in a Laser are a lot more treacherous than they were on the sunfish. However, they are much more fun and a heck of a lot faster.

The physics of a windward heel I was taught was to bring the center of effort on the sail directly over the center of bouyancy therefore streamlining the effort. Seems to make sense to me.
 
Okay, but if windward heel puts less wetted surface in the water, how come the boat is supposed to be sailed absolutely flat upwind?
 
Heeling to windward going downwind seems to be the most benefit in light air. Heeling it in heavy air is a very good way to do a death roll.

As far as going upwind, heeling to leeward effective in light air. It does reduce the wetted surface, but you're wasting part of the force created by the sail. Part of the force vector is pointed downward, which does no good in moving the boat forward. In light air you probably gain more from decreasing the wetter surface than you lose from not having the sail perfectly vertical.
 
computeroman2 said:
Okay, but if windward heel puts less wetted surface in the water, how come the boat is supposed to be sailed absolutely flat upwind?
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Sailing to windward is actually a faster point of sail and keeping the boat flat will help it to plane and be faster. If you can get the boat to plane you can effectively get the boat past the "hull speed"

If in heavy air conditions you can probably get the boat to plane downwind, though id imagine it would have to be pretty darn windy to get that to happen. Therefor heeling it to windward is a way to make it go faster to reduce the friction.

Going into the wind you lose more power from the sail be letting the boat heel and its near impossible to make the boat plane that way, so therefore you lose speed. the wetted surface factor does not equal (or come close to for that fact) the amount of power you lose going into the wind by not being as efficient as possible. Make sense?
 
Sorry, you couldnt be more wrong. Check out a graph of speed in relation to points of sail, they're readily available. As Far as planing the boat will plane off the breeze way before it will plane to windward. Keeping it flat is fast and just go with that when sailing to weather. It has to do with the relationship of hydrodynamic and aerodynamic forces along with the depth and angle of the foils in the water. Some people should be more reluctant to pass on bad advice.

Bunky9590 said:
Sailing to windward is actually a faster point of sail and keeping the boat flat will help it to plane and be faster. If you can get the boat to plane you can effectively get the boat past the "hull speed"

If in heavy air conditions you can probably get the boat to plane downwind, though id imagine it would have to be pretty darn windy to get that to happen. Therefor heeling it to windward is a way to make it go faster to reduce the friction.

Going into the wind you lose more power from the sail be letting the boat heel and its near impossible to make the boat plane that way, so therefore you lose speed. the wetted surface factor does not equal (or come close to for that fact) the amount of power you lose going into the wind by not being as efficient as possible. Make sense?
Click to expand...
 
Wow, planing a Laser upwind.....that'll be the day.

It was interesting to see the world's best sailors in the 2000 Games often sailed with about, hmmmm 15 -20 degrees of heel upwind in light air and heavy slop on the "washing machine" course. I never found out the thinking and how often they did it, but I can think of reasons.
 
In light air, upwind, (very light air) you'll see folks heeled well to leward and sitting on the centerboard trunk. It does help the boat go better to weather. The heel angle helps with going through waves and it allows the sail to maintain shape as there may not be enough breeze to keep it full standing straight up. Sitting up front and with heel will really reduce wetted surface.
 
The reason you need to sail the boat perfectly flat is to balance the heeling force. I'm trying to remember which book I was flipping through that had a great explanation... I think it was the North U Trim book. Check it out. Its a pretty good book to own if you ever plan on doing big boat sailing too.

they have a website. Just do a google for North U. Maybe add in sailing in the query.
 
Keeping the boat flat upwind in +5kts also reduces the leeway you'll expirence. With the boat heeled you'll have less CB in the water you'll get less righting moment and therby slip sideways. Also, because of the curvature of the hull the boat will have a tendancy to round up, which you'll have to correct with your rudder and further slow you down.
 
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