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Old 30-08-2011, 21:40   #1
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Beating Questions

Hi:

I keep hearing how some boats do not beat well, only getting an angle of say 60 degrees to the wind instead of say 45 degrees for a more efficient to wind boat. I am trying to understand this issue as I try to choose a boat.

First question, does this figure in common usage include leeway, or is that a further degradation of things?

Second, is the principle factor not being able to haul the sails in close because the shrouds get in the way? Or is the principle factor the keel? A combination, or something else?

Does the following model things realistically. I want to go somewhere dead upwind, so I must tack to get there. It is good and breezy, so I can get hull speed, say 7 knots. So ignoring speed loss in tacking, the vector of speed in the direction of my destination is cos(angle to wind) times speed. So with a speed of 7 knots, at 45 degrees the vector towards destination is 4.9 knots and at 60 degrees is 3.5 knots. In winds lighter than needed for hull speed, things won’t degrade quite so badly as the boat speed will be faster at 60 degrees off the wind than 45 off the wind.

So then if one throws in currents and tides, the 1.4 knot difference in the vector might well make the difference between slow forward progress in the direction of the destination, or none at all.

Is this about all there is to this or am I missing something?

Thanks

Boulter
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Old 30-08-2011, 22:00   #2
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Re: beating questions

Quote:
Originally Posted by Boulter View Post
Hi:

I keep hearing how some boats do not beat well, only getting an angle of say 60 degrees to the wind instead of say 45 degrees for a more efficient to wind boat. I am trying to understand this issue as I try to choose a boat.

First question, does this figure in common usage include leeway, or is that a further degradation of things?
OK Let state that I am no expert but as I understand it, these figures only refer to the apparent wind so leeway, adverse tides etc further degrade windward progress

Quote:
Originally Posted by Boulter View Post
Second, is the principle factor not being able to haul the sails in close because the shrouds get in the way? Or is the principle factor the keel? A combination, or something else?
All of these things plus the shape of the sails, baggy or blown out etc.

Quote:
Originally Posted by Boulter View Post
Does the following model things realistically. I want to go somewhere dead upwind, so I must tack to get there. It is good and breezy, so I can get hull speed, say 7 knots. So ignoring speed loss in tacking, the vector of speed in the direction of my destination is cos(angle to wind) times speed. So with a speed of 7 knots, at 45 degrees the vector towards destination is 4.9 knots and at 60 degrees is 3.5 knots. In winds lighter than needed for hull speed, things won’t degrade quite so badly as the boat speed will be faster at 60 degrees off the wind than 45 off the wind.

So then if one throws in currents and tides, the 1.4 knot difference in the vector might well make the difference between slow forward progress in the direction of the destination, or none at all.

Is this about all there is to this or am I missing something?

Thanks

Boulter
Thats pretty correct. Remember some boats point better on one tack compared to the other, there is a lot of thoughts on how often to tack as you approach your windward mark, tacking away from headers and not tacking when lifted and so on.
For a good explantation find 2 successful racers and get 3 opinions!
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Old 30-08-2011, 22:03   #3
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Re: beating questions

You pretty much summed it up. In sailing, sometimes just holding your ground is doing pretty good.
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Old 30-08-2011, 22:36   #4
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Re: beating questions

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Originally Posted by Boulter View Post
I keep hearing how some boats do not beat well, only getting an angle of say 60 degrees to the wind instead of say 45 degrees for a more efficient to wind boat.
In some cases you could be talking about the same boat.

If one sails about 45 deg angle to apparent wind, the course made good might only be 60 deg angle to true wind.

Make sure talking apples to apples when comparing upwind performance claims.
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Old 30-08-2011, 22:43   #5
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Re: beating questions

As a percentage that is a big drop in performance. Maybe enough to kill you if trying to beat off a lee shore.

Leeway will increase dramatically as speeds drop, so your hull speed scenario could well be your "best case".

Having said which, a lot of cruisers almost go out of their way to impede their boats performance, baggy sails, fixed 3 bladed prop, overweight, junk all over the deck, forestay sag. Fix all that and it can easily be worth 10 deg of pointing.


Each to their own , but I like sailing and thus prefer reasonable performance.
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Old 30-08-2011, 22:58   #6
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Re: beating questions

Quote:
Originally Posted by Boulter View Post
Hi:

I keep hearing how some boats do not beat well, only getting an angle of say 60 degrees to the wind instead of say 45 degrees for a more efficient to wind boat. I am trying to understand this issue as I try to choose a boat.

First question, does this figure in common usage include leeway, or is that a further degradation of things?

Second, is the principle factor not being able to haul the sails in close because the shrouds get in the way? Or is the principle factor the keel? A combination, or something else?
1. There is a difference between beating well and pointing well. To beat well has everything to do with hull shape. To point well is mostly about sail shape.

2. There is a difference between wind angle (pointing ability) and leeway. Your leeway may be a function of current, as well as slippage.

3. There is no "principle" factor. Nor is there a principal factor. Inboard shrouds promote better pointing than outboard shrouds. Hull shape can promote better pointing. Ballast/displacement ratios effect pointing ability. Sail trim, not to mention sail shape, makes a difference. Rudder design makes a difference. Crew position makes a difference. Mast bend and rake make a difference. All these factors work together to determine how a boat goes to weather.
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Old 31-08-2011, 13:31   #7
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Re: beating questions

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Originally Posted by Bash View Post
1. There is a difference between beating well and pointing well. To beat well has everything to do with hull shape. To point well is mostly about sail shape.

2. There is a difference between wind angle (pointing ability) and leeway. Your leeway may be a function of current, as well as slippage.

3. There is no "principle" factor. Nor is there a principal factor. Inboard shrouds promote better pointing than outboard shrouds. Hull shape can promote better pointing. Ballast/displacement ratios effect pointing ability. Sail trim, not to mention sail shape, makes a difference. Rudder design makes a difference. Crew position makes a difference. Mast bend and rake make a difference. All these factors work together to determine how a boat goes to weather.
Thank you Bash for the detailed response. To follow up directly, how much of it is the characteristics of the boat that are fixed, and how much is the condition and adjustment of the sails, the skill of the crew, and other things that can be controlled?

Can we ever be in a position to say something like "Canuck Comfy 42 will go 51 degrees off the wind including slippage with skilled crew and good sails and gear well adjusted, but is likely to go 56 degrees off the wind with unskilled crew and less pristine gear". Or am I trying to shove into the realm of science that which is really art?

I am trying to get a quantitative understanding of this instead of the "that boats sucks to windward" qualitative stuff that floats around everywhere. Maybe what I want isn't possible because of all the factors you alude to above. So many here insist that their boats sail well to windward, other say toss it, I'm in no hurry. The opinions seem to be black and white, no grey. I want the bloody number, not the emotion: "the velocity (assuming no current or tide, but including slippage) towards destination is 4 knots at hull speed of 7 knots". Then I can sum in the vectors that represent current and tide and other facters I perhaps don't yet know about, and get a resultant vector relative to the ground.

The underlying thing I am trying to get at is what exactly from a practical standpoint am I giving up if I get a boat that doesn't sail well windward.

Maybe I am starting at the wrong place. Being an engineer, I want to model the boat(s), then given likely voyages model the wind, then model the current and tide. Then I would have a quantitatative estimate of what a cruising slug can do vs a racer. If the answer is something like 10 days vs 7, I don't care, but if it is not possible vs 7 days, then maybe I want a different boat. Many will just accept that they will have to fire up the engine, but philosophically I don't want to do that.

Maybe what I should be asking is something like "how many days in July does it take to sail from Toronto to Halifax in boat type X, a cruising slug, and boat type Y, a fin keel spade rudder racer. How many days does it take in the reverse direction. What are the numbers with an expert crew and new well adjusted gear vs a greenhorn with sloppy old sails and a lazy crew". This question then incorporates in it's answer the characteristics of the boats, the skill of the crew, weather probabilities for July, the direction sailed, the prevailing currents etc. My hunch is for a racer it will take 2 to 3 times the time in the Halifax to Toronto direction given that the prevailing wind direction is something like west, and the prevailing water direction heads to the Atlantic ocean. My hunch/guess for a cruising slug is 3 to 4 times. Am I wildly off?

Boulter
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Old 31-08-2011, 13:44   #8
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Re: Beating Questions

Boulter:

Just to make your equation more complicated you will also need to factor in the sea conditions. When replacing a keel on a Farr 40 that I raced on the owner was asked what conditions he wanted the boat to perform best in e.g Marina de Paradise is where I race and the winds are 10 to 12 knots in flat seas (and warm). Or the conditions that I commonly sail in at Marina der She blows are 15 to 25 knots with a 3 foot chop and 5' swell. Bruce Farr would design the keel to the conditions. All of that considered there was the point about the crew as well -- The skipper and I knew that when the wind picked up, in order to make the boat point, you had to force the nose of the boat down. This was contrary to everything that I had been taught but what would happen is that by pushing the bow down the keel would get more lift and the boat would start pointing higher. I would need to change the trim of the sail slightly for the new configuration. After awhile the boat would lose its lift and then settle down and we would start the process all over again. On a cruising boat you would not be able to get that reaction from a boat while sailing upwind. What I am saying is that it is very hard to quantify whether a boat can go up wind well or not. Crew is a big factor, conditions are a big factor and wind speed also plays a big factor.
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Old 31-08-2011, 13:50   #9
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Re: Beating Questions

Many feel that sailing is as much art as science. If it was all the latter, all one-design boats would cross the line at precisely the same time and speed. With robots at the helms.
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Old 31-08-2011, 14:16   #10
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Re: Beating Questions

Quote:
Originally Posted by Boulter View Post
Hi:

I keep hearing how some boats do not beat well, only getting an angle of say 60 degrees to the wind instead of say 45 degrees for a more efficient to wind boat. I am trying to understand this issue as I try to choose a boat.

First question, does this figure in common usage include leeway, or is that a further degradation of things?

Second, is the principle factor not being able to haul the sails in close because the shrouds get in the way? Or is the principle factor the keel? A combination, or something else?

Does the following model things realistically. I want to go somewhere dead upwind, so I must tack to get there. It is good and breezy, so I can get hull speed, say 7 knots. So ignoring speed loss in tacking, the vector of speed in the direction of my destination is cos(angle to wind) times speed. So with a speed of 7 knots, at 45 degrees the vector towards destination is 4.9 knots and at 60 degrees is 3.5 knots. In winds lighter than needed for hull speed, things won’t degrade quite so badly as the boat speed will be faster at 60 degrees off the wind than 45 off the wind.

So then if one throws in currents and tides, the 1.4 knot difference in the vector might well make the difference between slow forward progress in the direction of the destination, or none at all.

Is this about all there is to this or am I missing something?

Thanks

Boulter
The ability to sail close to the wind is a very, very important characteristic of a sail boat, not only for racing but cruising too. Unless you want to be one of those people who just motor sail everywhere.

I'm no expert but I think the principle factor is the keel, deep keels allow the boat to point higher, but sails are somewhat of a factor too. The angle doesn't include leeway.

Most boats with fin keels sail pretty close to the wind though so I wouldn't worry too much about it.
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Old 31-08-2011, 23:03   #11
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Re: Beating Questions

Hi everyone:

My opinion in talking about winward performance, and comparing boats is that the only figure I am interested in is the total GPS tacking angle between two long tacks.

So go to winward pointing as high as you can in one tack. Let it stabilize and write down the "average" GPS course.
Then tack, point high, let stabilize and write down the new "average" GPS course.

The difference between the two courses is what I'm after in comparing boats.

In my 30 year old 31 footer, in mild winds (under 10 knots) I can't get it better than 120º ( with bimini, old sails, dinghy on deck, etc)

With stronger winds (under 20 knots) the angle gets better ( around 110º).

Dissappointing, but real!!

Regards
Toni Tutusaus
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Old 31-08-2011, 23:25   #12
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Re: Beating Questions

Sailors can sometimes do better upwind than their boat's nominal windward ability. That's because the wind is seldom constant in direction. Racing sailors in particular gain a sense of when to take advantage of lifts and tack on headers. The best of them watch the water to windward and look for patterns and information that help them anticipate changes in wind direction. They make note of typical wind patterns in a given area, try to determine whether the wind shifts are back and forth (oscillating) or persistent, and try to predict wind direction changes caused by tides, currents, topographic features, and weather fronts.

By sailing actively, alert sailors may be able to reduce the distance they have to cover in order to go upwind by 10 or 15 percent or more. This is quite enough to win races ... or claw off a lee shore ... or be the first to get a good slip and a stool at the bar.
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Old 01-09-2011, 02:54   #13
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Re: Beating Questions

One thing to keep in mind --

Sailing upwind involves different aerodynamic principles than sailing downwind -- or one principle, namely lift. It's a whole different ballgame. Any old boat with any old sails and rigging run by any old sailor will go downwind. And a reach -- involving as much drag as lift -- is also no challenge.

Start trying to go upwind, where the principle force is lift -- and all the rules change. Suddenly a little bagginess in your sails makes a huge difference. Suddenly you need to know a lot more about sail trim.

And a large percentage of cruising boats (like my last one) simply won't make miles to windward at any rate which makes it worthwhile -- so on goes the engine, and you find yourself motoring half the time.

You asked for numbers. There are two relevant direct metrics: 1. Angle to the apparent wind. That's what the sails feel and what you steer to; 2. Tacking angle on the chart plotter. That's the real geometry of your progress upwind. The indirect metric which you care about is velocity made good to windward. That's how you evaluate whether you are sailing too high or not -- whether you might make more progress made good by sailing a little lower and faster. Or the other way around.


My last boat, a Pearson 365, with a long fin keel and crude sloop rig with no traveller and no vang and somewhat bagged-out sails could not be sailed realistically to a destination upwind. Tacking angle was probably 120 -- 130 degrees, achieved at an apparent wind angle of about 45 to 50 degrees. That's in reasonable sea state conditions. With any sea running, it was even worse.

My current boat, a Moody 54, is much better. Bulb keel, semi-balanced rudder, and sophisticated rig. Sails are 10 years old and not in ideal condition, but so far not showing any visible bagginess. So she is, if not a great sailer, at least a somewhat above-average sailer. In reasonable sea state conditions, when beating to a destination upwind, I will usually hold an AWA of about 37 degrees, although depending on the wind and sea state this could be as little as 32 degrees or as much as 40. When reefed down, the angles get much bigger. We tack through an average of about 100 degrees when sailing for optimum VMG, although in a perfect wind (about 18 knots for our boat) and flat sea, I've seen close to 90. With any chop or less than perfect wind, 100 degrees can easily become 110 or 120 or more. As someone said, in conditions (low wind, rough sea) which keep you sailing much slower than hull speed (about 9.3 knots in our boat), leeway goes up and your tacking angle goes to hell.

So -- making progress dead upwind under sail is an art. It's a lot more work and more demanding of the boat than any other point of sail (someone said "beating is sailing twice the distance at half the speed").

Like most cruisers, I don't always bother to do it. I like sailing (as opposed to merely being out on the water, although I love that too), in more than small doses, and so when I'm out cruising, I like to plan the trip so that most legs are 40, 50, 60 miles -- at least 40 or 50. 40 miles beating in perfect conditions become 65 miles or more, and my plans don't always allow me enough time to beat a passage like that (often there are tides to consider, too), so the motor comes on. On the other hand, making 30 or 40 miles dead upwind is one of the most satisfying things you can do on a sailboat.
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Old 01-09-2011, 09:40   #14
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Re: Beating Questions

Hi:

Thank you Toni and Dockhead et al for the recent responses. I think I am now getting a practical feel for the limitations of beating.

I think that I can reasonably assume from all this that any boat I am likely to get will have a tacking angle of 120 degrees at best. Wouldn't hurt to assume 130. Any major improvement on that figure will likely involve major concessions that are not in the best interests of my goal, a reasonable old bluewater boat that doesn't bankrupt me, or cause my head to ring when it bounces off the ceiling down below.

Boulter
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Old 01-09-2011, 10:48   #15
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Re: Beating Questions

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Originally Posted by Boulter View Post
Hi:

Thank you Toni and Dockhead et al for the recent responses. I think I am now getting a practical feel for the limitations of beating.

I think that I can reasonably assume from all this that any boat I am likely to get will have a tacking angle of 120 degrees at best. Wouldn't hurt to assume 130. Any major improvement on that figure will likely involve major concessions that are not in the best interests of my goal, a reasonable old bluewater boat that doesn't bankrupt me, or cause my head to ring when it bounces off the ceiling down below.

Boulter
120-130 degrees tacking angle?? Better follow the trade winds on that cruise and hope you never have to beat Angle that the boat tacks through is a pretty bad indicator since so many other factors can influence your boat speed and hence the apparent wind and hence the angle after tacking.
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