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Old 02-12-2010, 03:56   #1
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Optimal Heel Angle

Beneteau Oceanis 411
10 to 13 deg is quite comfortable with good performance on a reach or beat.
More sail, more heel - she goes a bit faster - but does anyone know the 'typical' figure for an oceanis class for optimal performance ?

I'm guessing it may be 15 to 18 ??
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Old 02-12-2010, 04:24   #2
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I find for my Cal-39 15 seems to be best. After that I have the rudder over and the drag from that is about the same as just moving the traveler or reefing to sit up move. At 20 degrees heel I've learned I'm not really going faster just feeling like I am.
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Old 02-12-2010, 06:57   #3
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It depends what you mean by 'best'. Toe rails in the water is most fun - and it gets even more fun if I can plough into a wave whilst Skip is on the fore deck. That's what I aim for, anyway!
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Old 02-12-2010, 06:59   #4
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Balance is important in generating speed. If the boat developes more weather helm as it heels, reduce sail and sail flatter. When the rudder has to counter the weather helm, the boat is slower. Each design has a optimal angle of heel but generally 20 degrees or less.
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Old 02-12-2010, 07:58   #5
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More heel creates an asymmetrical under body profile and adds to slipping to lee (leeway). As you heel the boat will be trying to town head to wind and to prevent that you need to put the helm over creating drag and excessive forces on the rudder.

As others have said you want the boat to sail "balanced" and the designers usually are looking for something not more than 15-20° or so. You can usually tell when you are heeled too much by the amount the helm is held over past CL to hold your course.
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Old 02-12-2010, 08:00   #6
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with the original fixed 3 blade prop, it took large helm angle to keep it down when over at 15-20 degrees. But when I replaced it with a Kiwiprop, the weather helm was halved thus I went faster with less drag from the rudder. It is said that weather helm should about 5 deg. some weather helm is good Drac Verd seems to go best at about 15 degs heel. practical Sailor had an article re. flat wide transoms i.e. late model Catalina, Hunter and Beneteau. When heeled the sailing axis is off thus the keel can be at a negative angle to the water flow. They need to be sailed fairly flat. Nov 2009 I think.i
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Old 02-12-2010, 08:11   #7
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Heel angle on a properly rigged and trimmed boat is closely related to the power being produced. When you don't have enough power because of light wind, seas, or small sails power up the sails by deepening their camber or whatnot. The boat will naturally heel more, When you are sailing fast enough reduce power and heel by flattening the sails.

There is no proper heel angle. There is an amount of power needed for the conditions and that power will produce whatever heel angle it does. Sailing fast close hauled in heavy seas will require the most power and thus the most heel.

One should be able to trim away excessive weather helm at any heel angle. However some boats are just not designed well. And many old cruiser sails cannot be flattened.
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Old 02-12-2010, 08:33   #8
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The OP asked upwind and a reach, I think these are two different numbers. What does he mean by optimum? If it's pure speed then look at the knotmeter and try different amounts of sail. If optimum means some speed per comfort ratio for cruising then that's a soft number developed personally.

As others have said I don't know what is optimum for his boat, but for my Cal 40 on a reach more sail equalled more speed which involved a significant amount of weather helm/rudder angle. I was a little above a beam reach, more heel than optimum for upwind sailing, with about 10-15 degrees of rudder angle. Tucked in a reef everything goes to normal, lost maybe 0.5 knots of boatspeed (too long ago to remember exact numbers.) Shook out the reef, boat speed went right back up.

I think close hauled you're concerned about maximizing your L/D ratio not just maximizing power. On a reach since the sails are pulling more in the direction you want to go you can easily generate more power in the direction that you want to go than is lost in increased rudder drag.

Upwind my boat is pretty well balanced until a little more than 20 degrees of heel, then weather helm and boat speed suffer dramatically.

John
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Old 02-12-2010, 08:41   #9
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Quote:
Originally Posted by FraidNot View Post
Beneteau Oceanis 411
10 to 13 deg is quite comfortable with good performance on a reach or beat.
More sail, more heel - she goes a bit faster - but does anyone know the 'typical' figure for an oceanis class for optimal performance ?

I'm guessing it may be 15 to 18 ??
Depends on point of sail of course, but I've always heard 12-15 is optimum for a 393, and we have similar boats, displacement, etc. Personally, I really like the feel of my boat around 10-12 degrees, seems like it sits in nicely there and with minimal weather helm.

Like you, I usually putt around with less than 15 deg of heel if for nothing else than to just to keep the family happy down below.

I have a dock neighbor that races his 411 all the time- I'll have to ask him about heel angle. The limited time I've been on his boat while racing we were just sailing the boat based on tell-tales (no reefing required).

Frank
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Old 02-12-2010, 08:49   #10
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...I was a little above a beam reach, more heel than optimum for upwind sailing, with about 10-15 degrees of rudder angle. Tucked in a reef everything goes to normal, lost maybe 0.5 knots
Try flattening and twisting the sails more. You should be able to trim away that helm on a Cal 40 and just go fast. (My California boat is a Cal 36)

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I think close hauled you're concerned about maximizing your L/D ratio not just maximizing power.
More power is good so long as she's going the right direction (leeway). It is indeed the L/D ratio we're trying to maximize. Flattening sails the way to do it. And of course eventually a reef.

Regarding rudder angle: It should at least equal the leeway angle. Maybe a few degrees more. A well balanced rudder may take up this angle hands free on a well trimmed and designed boat. The weather helm to be avoided is that force that you must fight with the helm, regardless of the actual angle, somewhat...
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Old 02-12-2010, 12:34   #11
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GeoPowers - thanks that would be handy.
I sail with reference to the polar charts and these are very useful for seeing how close to original test data you can get. Handy indication of quality of trim.
You will see the race boats at 15 to 20 quite often - working hard against each other and all at that heel. I suspect a cruise/racer like Oceanis is indeed best at 15 or less but really seeking any emperical evidence, or long term user experience by someone who has worked on this idea.
Mark - you out there ?
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Old 02-12-2010, 13:01   #12
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There is no proper heel angle. There is an amount of power needed for the conditions and that power will produce whatever heel angle it does. Sailing fast close hauled in heavy seas will require the most power and thus the most heel.
I agree with daddle that an ideal level of trim is relative to sea state. I disagree that the most heel means the most power. Excessive heel leads to greater sail inefficiency PLUS more leeway.

I would also point out that on more modern design--and by that I mean plum bows and reverse transoms for longer waterlines--heel is rewarded less in terms of increasing waterline than on more traditional craft. Clearly, some boats respond to heel better than others. The old IOR designs needed significant heel to sail their handicaps.

A good way to experiment on any given boat is to set the instruments to measure VMG when going to weather. We've certainly noticed cases where we increase VMG after reefing even though we decrease speed through the water. I believe this is because the boat actually points better when it is heeled less.
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Old 02-12-2010, 13:14   #13
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I disagree that the most heel means the most power. Excessive heel leads to greater sail inefficiency PLUS more leeway.
We agree. There's more power, but it's being wasted. The hull, keel, and rudder cannot make good use of it and she goes sideways. So I'd say she's overpowered and flatten or reef the sails. But I wouldn't base the overpowered judgement on the heel angle. It's the other way around: the power I need produces some heel angle because of the sail efficiency.

In flat water I might end up at 15 degrees of heel, in seas maybe 30. At 15 degrees of heel in unfavorable seas I'd make no forward progress because of the power lost to bashing into waves.

So heel angle is not a rule or even a guideline. As you write, VMG is. Experience is. Comfort is. Cocktail hour is.
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Old 02-12-2010, 15:27   #14
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Daddle is right. This is a silly question. For a designer the optimum angle of heel is zero degrees. That's where the hull and foils work as designed. Once you start tipping things over it's all about VMG and it's different for every boat.
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Old 02-12-2010, 16:02   #15
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Daddle is right. This is a silly question. For a designer the optimum angle of heel is zero degrees. That's where the hull and foils work as designed. Once you start tipping things over it's all about VMG and it's different for every boat.
The OP did specifiy the boat the question was for, so prehaps not such a silly question?
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