rbhun

What is the best heel/pitch angle?

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Hi

We are getting better at racing - good enough to know we dont know shite :)

I have never paid too much attention to heel, I knew its better than flat, sometimes, but now I know there must be a good heel angle at certain wind speeds and angles. But I dont know what it is.

Is there a scientific way to do this? We are getting new sails including a code0, so we have to build new polars to get some target speeds and to find out how good we are. But I dont tknow how to compensate for trim..I cannot do every angle with all the heel, so I'd be glad if there is a scientific explanation...

 

Thanks

Balazs

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you already know that generally flatter is better; are you better off trying to figure out how to keep the boat upright with minimal rudder angle than trying to figure out angles of heel?

but what boat? LOA, LWL disp, sa/d, etc

any reviews of the hull form/shape/foils?

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A good set of VPP data for your particular boat would be where I'd start. That will give you some targets.

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Depends on your hull form.

IMHO Generally, in light air (1-7kts) you want to induce heel to:

1 help the sails take natural shape

2 reduce wetted surface and increase waterline length.

3. Point higher due to hull shape touching water.

any more breeze and you want to start to flatten the boat to her optimum heel angle.

SAIL SAFE 

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on a dragon your optimal heel angle is 11 degrees... (longest waterline)

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zero degrees, according to daughter #1. Son #1 and daughter #2 are all for it, however.

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What boat do you have? Every design has an optimal angle of heel and it varies according to conditions.

On long skinny boats, heel matters less than on wide boats, especially those with wide flat sterns.

If you want to jump-start your understanding of heel, spend a summer in a dinghy like Laser or Melges 14. The performance differences at different angles of heel on different points of sail in different conditions are transferred to physical sensations in your butt and on the tiller. Don't over-analyze it; just spend time sailing, responding to puffs and lulls, trimming in the sails and easing out, hiking out and leaning in, shifting your weight towards the bow and shifting aft. It's all about putting in the hours on the helm. Once you get to the stage where you're doing all that boat and sail trim without thinking about it, you are ready to get back into the less responsive bigger boat. You should find yourself automatically seeking the same trims and sensations as on the dinghy.

 

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Wow, lots of great answers! Thank you! To answer some questions, she’s a Beneteau Oceanis 411, which I bought as a fun/cruiser boat but it turned out pretty fast in our area (Balaton, Hungary) so we took it more seriously after some weekend regattas. This year we want to build the polars and determine target speeds as we modernize the old sheets and sails with new ones. 

As for getting in a laser or other small dinghy, I did that for about 10 years and then I raced as a crew in small keelboats. I do have a good feel about how she’s moving, but wanted to have a more professional approach. A big displacement keelboat moves very differently. I don’t think my experience in a 420 15 years before would tell me all I need to know about when to send six crew to the rail. 

Also in our lake light winds (under 8 knots) are very much the norm, so we generally have to induce heel not compensate for it. The question is, when? My captain used to tell me to heel for height, but he was a Star racer. Those are also very different from flat boats with genakkers.

Thanks for the article link and the idea about VPPs!

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2 hours ago, Somebody Else said:

Don't over-analyze it; just spend time sailing

This... with or without the dinghy bit.  Although applaud the dinghy recommendation as well

There is a scientific way to do  what you're asking. 

First way is You take Bob's advice and go get a set of VPP numbers.  if it's a popular design you might find a similar boat in the ORC Rating files.  If not you can pay someone to plug the numbers in or possibly talk to the original designer.

Second way is you find another similar boat and you go two boat tuning.  try this, try that, keep a log book  with settings, speeds, wind data, heal angles, who's on the helm etc... and you methodically go about figuring out what's faster and what's not.

Third way is a variation on the above, but using a data logger if you have the instruments to do it.   Log all the data into a data logger, pop it into a spreadsheet, and find the the max boat speeds for given configurations.  If you don't have the instruments to do it,  get something basic and do it manually.

The science is this.  Apart from the obvious "every boat is different" spiel, most yachts are designed for two basic angles:  0 deg (ie more or less upright) and some number between circa 10-20deg.   When the boat is going slow, the predominate drag force is wetted surface area.  When the boat is going faster (closer to hull speed), hydrodynamic drag kicks in.  There's a magic number where this cross over.  I can't remember the maths but wet finger it's probably about 1/3 or so of hull speed.

as @daan62 points out, there is an optimal heal which will probably give you a longer water line length which can (but necessarily will)  lead to lower overall hydrodynamic drag.   Equally healing the boat over can (but necessarily will) reduce your wetted surface area. A boat that has a more flared hull shape will actually increase its wetted surface by leaning over.  Take a look at the hull shapes from the '92 americas cup yachts and then beyond.  the boat that won was slab sided.  the boat that didn't, was less so.  Every boat there after was slab sided.

Healing the boat over *will not*  allow you to point higher.  Complete and utter myth.  In fact overall, it probably has the opposite effect.  What allows you to point higher (beyond rig configurations) is speed.  The faster you go, the more height you can get.  Leaning a boat over may give you that sensation, as the helm loads up and gives you a bit of feel you may not have otherwise had.  That can help you steer the boat to windward better in lighter winds, but in of itself doesn't give you more height.

In short, the scientific approach is careful experiments, with properly analysed data.

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Thank you, @Spoonie. I’d love to go out and do all this on the water and not in the computer. However season here starts in April. So till then, it’s all about science. 

Also since we’re on a lake with much more wind variation, it’s harder to see what a change like heel does, because it’s likely the wind has shifted since. 

Anyway, thank you for the explanation and the ORC file. I have the manufacturer’s polar file which is similar to this. However I have the Performance model with longer mast and keel, so I must do the polars the hard way. 

I’ll look into VPP too. 

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59 minutes ago, rbhun said:

Wow, lots of great answers! Thank you! To answer some questions, she’s a Beneteau Oceanis 411, which I bought as a fun/cruiser boat but it turned out pretty fast in our area (Balaton, Hungary) so we took it more seriously after some weekend regattas. This year we want to build the polars and determine target speeds as we modernize the old sheets and sails with new ones. 

As for getting in a laser or other small dinghy, I did that for about 10 years and then I raced as a crew in small keelboats. I do have a good feel about how she’s moving, but wanted to have a more professional approach. A big displacement keelboat moves very differently. I don’t think my experience in a 420 15 years before would tell me all I need to know about when to send six crew to the rail. 

Also in our lake light winds (under 8 knots) are very much the norm, so we generally have to induce heel not compensate for it. The question is, when? My captain used to tell me to heel for height, but he was a Star racer. Those are also very different from flat boats with genakkers.

Thanks for the article link and the idea about VPPs!

 

The righting moment of boats that depend on rail meat is greatest when flat, but when the primary righting moment if from the keel then there is none until there is some heel, so sometimes heel is good. Talking powered up here, not light air of course. 

 One thing is certain, too much heel is bad. The keel is a foil, just like the sails. Too much heel means scrubbing sideways...always slow. 

 It's a bunch of compromises best resolved by VPP, really. 

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Foe those with a racegeek d10 you can take the guesswork out of this completely.

The main perfromance page displays heal angle along side heading and boatspeed.

The free analytics includes the ability to drill down to an individual segment of the race and look at the heal angle. So you can find the numbers from when you know you where fast against the boats around you.

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3 hours ago, Spoonie said:

What allows you to point higher (beyond rig configurations) is speed.  The faster you go, the more height you can get. 

How is this true when the faster you go the further forward the apparent wind moves?

 

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4 minutes ago, W9GFO said:

How is this true when the faster you go the further forward the apparent wind moves?

 

Because your ability to gain height sailing up wind (as apposed to just simply pointing high) is a function of the speed of water over your keel.   Angle of entry on your sail plan can be adjusted accordingly.    There is of course, limits.  and 18' skiff or high performance cat for example sail really wide angles.  but like boat for like boat, you can not expect to sail higher than the next guy without first having speed. 

Point high enough, with slow enough speed, your keel no longer generates lift you and just slide sidewise.  Sure you might be pointing in the right direction but you've gained nothing.  classic example of that is boats on a startline all winding up from zero.  They all slip sidewise untill they get moving.  Something you need to be careful of if you've established an overlap leward of someone going slower than you on a start line.  Lots of similar examples like close reaching with a kite.

It's a balancing act.  Sail fast, grab height, repeat.  person who sails the fastest with the most overall height up the course wins. 

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12 hours ago, rbhun said:

Hi

We are getting better at racing - good enough to know we dont know shite :)

I have never paid too much attention to heel, I knew its better than flat, sometimes, but now I know there must be a good heel angle at certain wind speeds and angles. But I dont know what it is.

Is there a scientific way to do this? We are getting new sails including a code0, so we have to build new polars to get some target speeds and to find out how good we are. But I dont tknow how to compensate for trim..I cannot do every angle with all the heel, so I'd be glad if there is a scientific explanation...

 

Thanks

Balazs

Upwind or Downwind?

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14 hours ago, rbhun said:

Hi

We are getting better at racing - good enough to know we dont know shite :)

I have never paid too much attention to heel, I knew its better than flat, sometimes, but now I know there must be a good heel angle at certain wind speeds and angles. But I dont know what it is.

Is there a scientific way to do this? We are getting new sails including a code0, so we have to build new polars to get some target speeds and to find out how good we are. But I dont tknow how to compensate for trim..I cannot do every angle with all the heel, so I'd be glad if there is a scientific explanation...

 

Thanks

Balazs

On a Benetau 411(12.5m), you can probably want it around 15° below ~7 knots boatspeed (Fn0.3-0.35) in the pursuit of minimising wetted surface area and viscous drag. Going more than this - say 20°, you can start introducing resistance from the rudder and keel broaching the water surface. You also have diminishing returns as what you gain in boatspeed you loose in leeway angle as your appendages become less efficient, so i think 15° is safe and beneficial, but feel free to disagree - it wont suit all boats.

Any faster than 7 knots and wetted surface area is no longer a primary concern, so get the boat flat so your appendages work as efficiently as possible and your waterline is as symmetrical as possible - ie. the flatter the better.

In answer to your real question. Yes there is a scientific way to do this, however, not without some parameters that are pretty difficult to measure by hand. Even then, the easy equations for resistance are based on tow tank testing and calculating where you are on a spectrum of towed model data. This paper-> The Influence of Heel on the Bare Hull Resistance of a Sailing yacht. is pretty good example of that, but unless you're up to speed with terminology of design ratio's(BwL/Tc=waterline beam/bare-hull draft), you'll probably find it more greek than sailing. I haven't touched on appendages at heel and weather helm, but you can look into those as major factors in optimum heel too.

 

 

 

Edited by toestrap
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Beamy design for reference. I've been trying to keep to 20 deg as we're focused exclusively  on reducing wetted surface area at anything below 10 knots. More than 10 and we're trying to depower to hold to 20 deg, as we want to run on the chine, not dig it in (drag goes up enormously). I'll start digging the chine in at 25 deg.

I have dual canted rudders though that are near vertical at this heel angle, I'd be expecting a 411 at 20 deg is starting to really slip sideways.

Can you measure your leeway on board?

Cheers!

SB

 

  

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If you have a speedo simply go up wind for a few minutes at different angles of heel. Write it down. Tack and do the same thing. Do this is various wind speeds and you will have your answers. Science is not science without data. More data the better.

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4 hours ago, Spoonie said:

Because your ability to gain height sailing up wind (as apposed to just simply pointing high)...

Okay, I took you literally when you said "What allows you to point higher... is speed" .

If you fall off a bit to gain speed so that you make better way upwind, then you are not "pointing" as high as you just were. Isn't that correct?

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What follows is a tangible approach to Mr. Perry's recommendation above. 

Your easiest starting point is to get the speed guide for the boat from ORC, which is the output of the ORC VPP.  There are lots of 411s in the database.  You could find a boat that closely matches your configuration (sail dimensions, keel and displacement, age, etc) and the order a copy of the Speed Guide for that boat.  The Speed Guide will tell you roll angle for wind strengths from 6 - 20 knots.

The way you do this is register for Sailor Services on orc.org (upper right corner of the home page), and then search for Oceanis 411 in the database.  You will find about 10 active or recent ratings.  There are some important considerations.  ORC uses a hull file to run the VPP so you will need to be sure you have the right file.  Draft and displacement are some of the telling dimensions, and they are listed on the certificates of the boats you are looking at.  Once you find a match, you can easily order the speed guide, which will cost you 50 euros.

This is hit and miss, but would be close enough if all you care about is roll angle.  The better way would be to actually get the boat rated by a local ORC region.  In Hungary, you are supported by the ORC central office directly, and there is a local rating officer whose name is listed at the ORC website (https://orc.org/index.asp?id=64).  He can take you through the process.  You will come away from the process knowing a lot more about your boat.

I hope this helps you.

crash out/

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26 minutes ago, W9GFO said:

Okay, I took you literally when you said "What allows you to point higher... is speed" .

If you fall off a bit to gain speed so that you make better way upwind, then you are not "pointing" as high as you just were. Isn't that correct?

Kind of not really.  There was a whole thread on crabbing upwind somewhere.  

There is a theoretical angle to true which gives you best theoretical vmg to windward (in flat water, steady wind and all that guff).  If you go above this, you go slower, Leeway increases, rig drag goes up, generally badness all around.  If you go below it, you go faster but lose ground.   If you go faster then carry that speed and go higher then you gain height without the Leeway.   Fast, high,fast, high, fast, high, repeat.  80% technique.  20% rig setup

You can point high, but you need maximum speed first.   The whole thing gives the appearance of “good height”

 

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Lots of great answers again, I’m overwhelmed! Thank you! I decided to start with a custom VPP - orc seems like a good cheap place and I also found this: http://www.avalon-routing.com/en/polars/ which looks very detailed. Will also build up a database (till I actually get the boat unwrapped) from the orc polars already there and see how much they overlap. None seem to be the long mast version, so they should serve as very conservative targets when we can test them in real life. 

I have one follow up question which is more about polars than heel, sorry: why are polars in true wind speed and angle not in apparent? To me it seems all I need is apparent in both, and since it’s specific to the boat, it must be easy to convert (except for tide of course)? This baffles me. 

As for heel, I’ve learned that wetted surface is the important part, till the point where the speed is higher than a magic point. After that, I assume, flatter is better. Now some said this is about 1/3 of hull speed, some said it’s around 7 kts. The theoretical hull speed of my boat is 8kts so that’s quite a difference. And I don’t think a big displacement boat like the 411 can break thru the hull speed barrier. Now this I have to work out. She seems to go better at some heel in very light winds, so I have to concentrate on that part. Heavy winds, you get on the rail as much as you can. 

I found that iRegatta has heel from the iPhone sensor so that’s good to start. 

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Hi RBHun

Have you thought about contacting Beneteau or finding out if there is an owner's association which could share info with you?

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this may help some. I was looking for targets.

http://intersessions.com/411/411polars.html 

The last page of the 36.7 tuning guide has the chart you are looking for. But of course you want it for your boat.

http://www.blur.se/polar/first367_quantum_tuning_guide.pdf

http://www.blur.se/polar/first367_performance_prediction.pdf

The target market of the oceanis wasnt racers so that may be why it is harder to find.

I believe this is the tuning guide for your boat but it doesnt have the target speed chart in it.

https://www.neilprydesails.com/images/pdf/b41_1_tuning_guide.pdf

might find more interesting things here.

https://www.neilprydesails.com/beneteau-tuning-guides

I'll reach out to someone I know at beneteau to see if they know where to find a chart for target speeds. You can make that chart from the polars in the first lnk. but alot easier to find one already made.

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Foe those with a racegeek d10 you can take the guesswork out of this completely.

This is complete rubbish. There is no possible way to determine optimum heel angle from logged data, none.

 

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ThAnn’s @Baldur  unfortunately the 411 and the 41.1 is two completely different boat. 

I have found the polar you sent on the Beneteau catalogue. However it doesn’t state if it’s true or apparent wind speed/angle. Also, I have the longer mast, and installed a Code0, genakker, and a significantly larger spi than the recommendations (we are on a lake with light winds). 

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Here is a list of Benetaus, and some links appear to provide VPP info, but it doesn't appear to be included with the links to the OP's model listed here??  Maybe the designers, Groupe Finot can provide this?

http://www.shipsnetwork.com/an/boat/boatdata/?pdfhersteller=2917&manufacturer=Beneteau&page=#liste

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You've got the basics sorted (reducing wetted area in the light and as flat as possible in breezy conditions).

Going beyond the basics requires work to know the boat.

Just sail the boat close to others boats of similar speed. Tweak stuff (one thing at a time in small increments) and you will soon find what makes the boat go fast.

For finding the limit between heeling the boat and stopping the boat heel, it is a gradual thing, your best bet is good communication with the helmsman. If there is too much heel the boat will try to head up so basically as the wind strengthen , you move weight to windward slowly so that the rudder is always nearly neutral but not quite, just a few degrees of weather helm. That's a good starting points again each boat is different so you need to experiment a bit and it isn't only about heel, sail shape also matters a lot.

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23 hours ago, rbhun said:

Hi

We are getting better at racing - good enough to know we dont know shite :)

I have never paid too much attention to heel, I knew its better than flat, sometimes, but now I know there must be a good heel angle at certain wind speeds and angles. But I dont know what it is.

Is there a scientific way to do this? We are getting new sails including a code0, so we have to build new polars to get some target speeds and to find out how good we are. But I dont tknow how to compensate for trim..I cannot do every angle with all the heel, so I'd be glad if there is a scientific explanation...

 

Thanks

Balazs

When you start figuring out the angles and heeling, it's a good idea to have one of the crew as heeling responsible/weight placement responsible. The pit person, for example. Somebody who doesn't have to stare at sails at all times :) This weight trim is one of your main weapons, and an area where you can easily beat other boats, if they're sloppy about it. Where the crew sits or stands, should almost always have a purpose. Even on bigger boats. 

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23 hours ago, rbhun said:

Hi

We are getting better at racing - good enough to know we dont know shite :)

I have never paid too much attention to heel, I knew its better than flat, sometimes, but now I know there must be a good heel angle at certain wind speeds and angles. But I dont know what it is.

Is there a scientific way to do this? We are getting new sails including a code0, so we have to build new polars to get some target speeds and to find out how good we are. But I dont tknow how to compensate for trim..I cannot do every angle with all the heel, so I'd be glad if there is a scientific explanation...

 

Thanks

Balazs

https://www.sailingworld.com/how-to/steering-downwind-tom-whidden#page-2

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Rbhun, 

I know you're looking for a scientific numbers based approach but don't forget the simple part of practice and getting to know your boat. 

If you really want to isolate heel angle from both sail trim and heading, go out with your crew on a non race day and find some open water and don't sail to any particular mark. Exaggerate or 'over-heel' the boat on every point of sail and try to 'feel' the moment the boat slows down. Pinch and back off.  Tweak, trim and shift weight. Try not looking at any instruments(including a knot meter) and forget about the numbers. 

 

 

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24 minutes ago, fufkin said:

If you really want to isolate heel angle from both sail trim and heading, go out with your crew on a non race day and find some open water 

As I said it’s not very easy to have the same wind for longer (meaning more than a ten minutes) on our lake. But you just gave me an idea. 

 

Can I do this under power? I’m basically looking for the smallest wetted surface. Can I just start the engine, set it for say 4 knots and try to heel the boat and see how much it changes? That will take all the wind changes out of the equation. Sure it will also neglect forces like change of the lateral force point of attack in the sails when heeled, but we said that’s much less important. 

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...and here I was trying to keep it simple. I'll give you the short answer. No I wouldn't really approach it like that. Even though your trying to theoretically isolate heel angle, it is the interplay between heel angle, trim(which changes as you heel) and heading(what the boat wants to do as it heels and subsequent rudder force needed to steer) that your trying to pinpoint, so doing it as a motoring exercise, at worst might just put air in the lines from all the induced heeling!!

I'll let someone in a higher pay grade to give you the longer answer. (Theoretically you are suggesting what a tank test would try to accomplish but there are many variables).

(but hey, give it a try anyway if you really want to, what the hell)

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Personally I think you are over thinking it.  And I know you're all wrapped up for the cold, but all the theoretical exercises in the world will give you is a set of rules of thumb which you need to repeat with time on the water. 

What's important is the knot meter. 

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36 minutes ago, Spoonie said:

Personally I think you are over thinking it. 

yeah, I tend to do that :)

anyway thank you everybody for all the answers, I learned a lot today! :)

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The basic answer on the polar diagrams:  ORC's polars in the speed guide provide true wind on the right and apparent wind on the left.  The tables provide only true wind.  You can also open the .slk file in a spreadsheet and calculate the apparent wind from the true wind angle and boat speed and develop a custom table.

If you can't find a boat in the ORC database that matches your rig, then the roll angle will be wrong.  The driving force of the rig is a primary input into the VPP.  You might want to measure the boat and get an ORC-club certificate for 52 euros.

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on an Oceanis 411 you aren't going to be able to do much about heel unless you have twenty 200 pound crew onboard anyway.  If you are powered, put as many people on the high side as you can.  Other than that, enjoy the ride.

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I tend to sail through the seat of my pants and as such tend to over simplify. My advice is sail for speed and whatever heel angle and sail settings that put the boat in the groove, then that's what you want. At this point, I try very hard to maintain a constant heel angle as Buddy Melges suggests. I focus on speed over the keel and keeping that mast angle locked. I dunno, seems to work well.

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On 3/4/2019 at 10:32 PM, NORBowGirl said:

When you start figuring out the angles and heeling, it's a good idea to have one of the crew as heeling responsible/weight placement responsible. The pit person, for example. Somebody who doesn't have to stare at sails at all times :) This weight trim is one of your main weapons, and an area where you can easily beat other boats, if they're sloppy about it. Where the crew sits or stands, should almost always have a purpose. Even on bigger boats. 

Very true, especially as he says they Re on a light wind lake. 

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16 hours ago, bgytr said:

on an Oceanis 411 you aren't going to be able to do much about heel unless you have twenty 200 pound crew onboard anyway.  If you are powered, put as many people on the high side as you can.  Other than that, enjoy the ride.

I am not sure about this. IME it matters a lot in light air.

Even just 5 guys of average size will weight 350 to 400kg (French weight so not that big), on the leeward rail that's enough to make the boat heel by more than a few degrees. In the light it is all about momentum, if you are heeled a bit, the hull will be less draggy, your sails will have a better shape and a small puff might get you some so much needed momentum that you might manage to maintain for some time. The others will claim that they were "unlucky" with the fickle wind and got stuck but in reality it is always the same boats who end up in front because they know how to make the most of the little wind they get.

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On 3/3/2019 at 11:48 AM, Bob Perry said:

A good set of VPP data for your particular boat would be where I'd start. That will give you some targets.

rbhun,

The esteemed Mr Perry was being subtle.  The real answer is that you don't have the time and resources to build a set of polars.  

If your goal is too improve your sailing performance you buy polars. 

HN

 

 

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