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Sailing to windward

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NCBrew
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Initially Posted - 08/12/2010 : 12:31:37

How close to the true wind can your Catalina 25 standard rig sail in degrees? Is it different in different wind speeds.

NCBrew

1998 Catalina 250WK
Ravaging
Albemarle Sound,NC

I spent most of my money on boats and beer, the rest I just wasted.

Edited by - on

Steve Milby
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Response Posted - 08/12/2010 : 16:18:47

Most sailors and sailing opinions agree that most cruising and racing/cruising sailboats generally sail at about 45 degrees. Racing boats can do better than that. I'm sure someone, sometime, must have actually measured the sailing angles of sailboats, but I have never seen or read of them. Nevertheless, it's generally accepted, probably because it's close to what we can observe when we sail and tack a boat. Moreover, we know that most sailboats sail at about the same angle to the wind, because, when we race, we can see that few sailboats are capable of out-pointing the other boats by more than a degree.

Boats can be designed to point much higher, but, in order to do so, the boat becomes a limited-purpose sailboat; i.e., it is only good for racing, and has only the sparsest accomodations for cruising.

Speed begets pointing. As a sailboat's speed increases, it's ability to sail closer to the wind also increases. The best sailors know how to get the maximum speed out of the boat, and, accordingly, they can also out-point the other boats. Friction is a limiting factor with sailboats. By reducing friction, we can increase boat speed, and thereby increase pointing ability. Iceboats reduce friction significantly, enabling them to reach extraordinary speeds and to sail extraordinarily close to the wind.

A boat can generally point higher in higher wind speeds, as long as the size and shape of the waves are minimal. The higher wind speeds enable the boat to sail at higher boat speeds, but, if the waves build in size, they rub off some of that speed when they smack the bow of the boat.

I haven't answered your question with regard to a C25 standard rig, but I don't think anyone here can answer that question specifically.

Edited by - Steve Milby on 08/12/2010 16:29:21

Stinkpotter
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Djibouti
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Response Posted - 08/12/2010 : 16:22:41

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by NCBrew
 Is it different in different wind speeds.<hr height="1" noshade id="quote"></blockquote id="quote">Yes, due the varying efficiency of the keel the sails. In "reasonable" conditions, most of us tack through about 90 degrees, which means we're generally beating to about 45 degrees of true wind. Better sails allow a closer angle, and more speed does, too. In very light air, you'll benefit from falling off a little, easing the sheet a little, moving the "movable ballast" to leeward, and giving up some pointing for speed. If you point too high in light air, you'll probably slide to leeward more while moving slower.

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Stinkpotter
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Response Posted - 08/12/2010 : 16:23:52

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Steve Milby
 I'm sure someone, sometime, must have actually measured the sailing angles of sailboats, but I have never seen or read of them.<hr height="1" noshade id="quote"></blockquote id="quote">Sure you have, Steve--it's called a polar chart.

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Steve Milby
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Response Posted - 08/12/2010 : 16:35:52

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Stinkpotter
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Steve Milby
 I'm sure someone, sometime, must have actually measured the sailing angles of sailboats, but I have never seen or read of them.<hr height="1" noshade id="quote"></blockquote id="quote">Sure you have, Steve--it's called a polar chart.
<hr height="1" noshade id="quote"></blockquote id="quote">
You're right, Dave. I didn't think of that. But I've never seen one for C25s, although many people have asked about them on the forum, and I don't recall anyone ever finding one.

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skrenz
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Response Posted - 08/12/2010 : 17:13:29

That's an interesting question. Several different factors play into the answer. I will list a couple here and I'm sure that others will add.
In your post you specifically spoke about the "true" wind. There is also apparent wind. As you sail towards the wind, essentially the wind seems to track around closer to your bow the faster you go. You have the speed of the wind coming at you and your speed going at the wind.

So lets say that you are sailing north and the "true" wind is from the Northeast. As you pick up speed, the wind apparent to you will seem to turn more and more North Northeast. The amount it turns towards the direction you are sailing is related to how fast you are going.

What you want to know is what is the angle to the true wind that the boat will sail but what you need to know is at what angle to the apparent wind will the sail be effective.
The maximum you can pinch into the wind depends upon several different factors but they essentially boil down to two: how good are your sails, how well do you have them set. Sailing, especially tacking into the wind, is like flying an airplane. It all depends upon the amount of lift you can generate. The difference is though that on an airplane the shape of the wing, which is what generates lift, is fixed. On a sailboat the sail, which is what generates lift just as a wing does, is variable.

There are two situations I can imagine where the maximum angle to the true wind might come in handy. One, you are planning a cruise and you want to know what course you can reasonably steer. Second, you are on a race course and you want to know if you can make the next mark. In either situation there are two complicating factors to take into account. First, all sailboats have leeway. That is they slide sideways to the wind a certain amount. How much depends on the boat. Second, wind is seldom steady at the same angle over the course of a track. You may start out on one bearing but need to fall off as the wind heads up or head up as the wind falls off.

Essentially, I think it comes down to you knowing your own boat. Your Catalina 25 will sail differently from mine. Your experience tells you what course to the wind you can reasonably steer. Do keep in mind though, that its often not the best choice to steer as close to the wind as you can. Sometimes it is often more effective in the long run to sail more off the wind and tack, going a longer distance, than to pinch tightly into the wind going the shortest distance. The reason is because you loose speed pinching and gain speed falling off. Often the best plan is to sail faster and a further distance than slower and a shorter distance. Its also more fun

Edited by - on

Stinkpotter
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Response Posted - 08/12/2010 : 19:36:21

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by skrenz
 The maximum you can pinch into the wind depends upon several different factors but they essentially boil down to two: how good are your sails, how well do you have them set.<hr height="1" noshade id="quote"></blockquote id="quote">There's a third important factor--boat speed. The more speed to windward, the less leeway.

Once under way, the common question is when should I tack to clear the point over there, or to make the windward race mark, etc. Assuming you're pointing about as high as you can, and ignoring your apparent wind (which varies by wind speed), the simplistic answer is when the place you want to reach is just a little aft of directly abeam (95-100 degrees). Apparent wind makes it seem like you can sail much closer to the wind, but it's an illusion. If you can sail just a little higher that 50 degrees off the wind (100 from your current tack), that's great, but giving yourself a few extra degrees also gives you (1) the possibility of a little extra boat speed, and (2) a little margin for error. Currents also play a big factor--you can read up on calculating for "set and drift".

Edited by - Stinkpotter on 08/12/2010 20:28:41

Stinkpotter
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Response Posted - 08/12/2010 : 19:41:30

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Steve Milby
 ...I don't recall anyone ever finding one (polar chart for a C-25).
<hr height="1" noshade id="quote"></blockquote id="quote">Nor I, although studying one for almost any boat in that general size and category can be very enlightening. They are generally a curve for VMG directly to windward and directly downwind at various wind speeds and heading angles off the wind--that pretty much tells the story. In fact, the polars for almost any cruising boat gives us an idea of how (in relative terms) we can maximize our windward performance on or off the wind by not sailing as high as it would appear we can, or not going dead down wind.

Edit: For anyone (not Steve) not familiar with "VMG" (Velocity Made Good), it's a measure of the speed at which you are making progress in the direction of your ultimate objective, such as an upwind race mark, while sailing at an angle to that objective on each tack. The point is that your progress to windward might be better if you sail slightly lower (more off the wind) than your highest possible course, where you will achieve greater speed. The same is true downwind--sailing dead downwind can take longer to get to a downwind destination than sailing somewhat off the wind and jibing over to reach the destination, because of the greater speed you can attain at an angle than on a dead run. You can see that technique on Americas Cup races, for example--they never sail dead downwind.

Edited by - Stinkpotter on 08/12/2010 21:19:30

Steve Milby
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Response Posted - 08/13/2010 : 10:16:43

That's what I love about sailing. For every rule, there are innumberable exceptions. There is wide agreement that sailing DDW is slow, except, IMHO, when the wind is very strong, I believe it's the fastest way downwind. If your destination is DDW, the shortest distance to that destination is also DDW. Therefor, if you sail a broad reach, you must be able to achieve a higher speed than if you're sailing DDW, because you will have to sail a longer distance to get to the same place. I believe there are circumstances when you can't gain any significant speed by broad reaching, and that your quickest way DDW is by sailing as close to DDW as possible.

Imagine that you're sailing a 30' IOR design boat downwind in 18-25 kts of wind with twin headsails and the mainsail. When you're sailing as near to DDW as possible with those sails, the boat is constantly planing and the boat speed is nearly 9 kts. How much more speed can you expect to get out of that boat by broad reaching? I crewed on such a boat in those conditions, and the skipper and crew all agreed that the boat was going about as fast as it was capable of going, and that broad reaching wasn't likely to increase it's speed significantly. We held our course as nearly DDW as possible, while most of the other boats broad reached, and we finished first in class after racing 70 NM, about 90% of which was downwind.

I believe that, if the winds are strong enough, sailing DDW in an IOR boat is the fastest way downwind.

I have experimented with broad reaching downwind in moderate winds vs sailing DDW in moderate winds, and have not usually seen a significant advantage in broad reaching vs. sailing DDW in moderate winds.

I have seen a tremendous advantage, however, in being able to anticipate changes in windspeed, so that you can broad reach in lighter winds and bear off DDW in the puffs. It seems to me that, what makes it worthwhile to broad reach is the anticipation of a change in windspeed, because when there is a significant change in windspeed, there is usually also a significant change in wind direction, which increases the benefits.

The above comments apply only to older IOR design boats, such as the C25. They don't apply to modern ultra light racing boats, which are designed to plane more easily, in lighter air.

I believe that many of the comments made by authors represent generalities, and their opinions are often colored by the fact that they are thinking in terms of the hi-tech racing boats that they are accustomed to sailing, and not to the older designs that most of us everyday sailors sail. It's worthwhile and interesting to experiment on your own boat, to see if it behaves as the experts predict it should, or if it behaves better or worse.

Edited by - on

aeckhart
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Response Posted - 08/13/2010 : 10:40:22

Generally the C25 wing keel is not known to be a good upwind boat. However,I have observed over the years that my wing keel will point higher without significant loss in speed the greater the heel on the boat - probably because as the wing becomes more vertical in the water it imparts more leeward resistance. This is a slightly different phenominon than a "lift" in that it can be sustained over a longer period of time especially when the heel is induced by adding weight to leeward.

Edited by - aeckhart on 08/13/2010 10:45:55

Stinkpotter
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Response Posted - 08/13/2010 : 15:46:30

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by aeckhart
 ...I have observed over the years that my wing keel will point higher without significant loss in speed the greater the heel on the boat - probably because as the wing becomes more vertical in the water it imparts more leeward resistance...<hr height="1" noshade id="quote"></blockquote id="quote">That wouldn't surprise me, given C-25 WK's unusually shallow keel with its proportionally large wings.

To Steve's point on sailing DDW, no argument. But I've seen downwind VMG polar charts that suggested otherwise (can't say for what boat), and I've watched racers do otherwise--including AC boats--probably in light to moderate winds that couldn't push the boats to hull speed DDW. (For some heavy air cases, I'll have to get out my Freemantle tapes--except my VCR hasn't been hooked up for years.) It seems like in the races I've crewed in, by the time we made the windward mark, the wind had shifted just enough that the rhumb line to the finish was off DDW anyway, so I don't know what the skipper would've done if we were going DDW.

Edited by - Stinkpotter on 08/13/2010 15:48:50

Jmurfy
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Response Posted - 08/13/2010 : 20:55:49

My new sails made a big difference this year in my pointing ability.

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NCBrew
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Response Posted - 08/14/2010 : 03:52:41

Thanks for all the enlightening answers. Now the next question? Does anyone have a polar chart for the C25?

Edited by - NCBrew on 08/14/2010 03:53:05

Steve Milby
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Response Posted - 08/16/2010 : 09:23:48

If nobody has one, you can create your own polar chart. The procedure for doing so is described at the following website: http://www.oppedijk.com/zeilen/create-polar-diagram

That website illustrates, however, why you're not likely to find a polar chart for C25s, and why any polar chart should be viewed with some skepticism. It takes a lot of time and effort and thought and accurate equipment to create an accurate polar chart, and few, if any, C25 sailors would be motivated to put forth that much effort.

The polar chart will only be as valid as the information used to create it. If the knotlog used to record boat speed is inaccurate, the polar chart will be inaccurate. If the wind instrument used to measure windspeed is not accurate, the chart will be inaccurate. Likewise, other variables can skew the results, such as the place where the sailing takes place. Computer geeks say, "garbage in - garbage out."

Moreover, after a sailor has accumulated all the necessary data, how many are likely to be so generous as to share his data with his opponents, so they can use it to beat him?

If you want to learn to sail your boat fast and well, my advice is to race, and find out who are the best racers, and crew for them and chase them around the race course, watching them and learning from them, until the day when you can overtake and pass them. If you chase a guy like Derek Crawford around a few times, you'll learn much more than you'll learn from a polar chart.

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djn
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Response Posted - 08/20/2010 : 10:19:30

Mine did not point very high when I got it, but after putting on a good boomvang, down haul, and traveler car with some actuall side to side movement, it pointed a lot higher.

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Stinkpotter
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Djibouti
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Response Posted - 08/20/2010 : 10:52:08

Sail condition is also a big factor.

There's also the issue of how high you're "pointing" versus how high your're actually sailing. This is where a GPS is a necessary tool, since it knows nothing about where your bow is pointed, but everything about where you're actually going. Especially in light air, if you point too high and trim too hard, your sails might tell you you're not luffing, but your boat speed might drop to the point that your keel isn't "lifting" as much as it should, and your actual track is significantly to leeward of where your bow is pointed. As you start to point up, watch your GPS heading compared to your compass heading. If the GPS heading doesn't go higher toward the true wind (or even drops a little) while your compass reads higher, you're losing out to leeway, and you'll probably go faster and just as high (according to the GPS) by falling off a little. Give the GPS a few seconds to recompute after each change in heading--it needs to get some data points to calculate a change in track and speed.

If you find a polar chart for almost any boat (they're around on the web), you'll see that the best VMG (progress toward the windward objective) is at a higher angle in stronger winds than in lighter winds (represented by separate arcs). This is the kind of data that Steve refers to--it's very labor-intensive to collect and needs lots of different but steady conditions. Currents, gusts, varying sea-states, etc. will screw it all up.

Edited by - Stinkpotter on 08/20/2010 18:17:27

pjeffarch
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Response Posted - 08/29/2010 : 13:10:42

Wow - never had heard of a polar chart - thanks for all the great info gang!

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Derek Crawford
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Response Posted - 08/30/2010 : 08:44:32

Thanks for the compliment Steve!
I'm a great proponent of not sailing DDW. I sail with the wind over the windward corner of the transom and make minor course changes as necessary to keep it there when the wind shifts. If the shift is too large to accomodate in this way, then I will rotate the sail plan accordingly (ease pole, trim main, or vice versa).
I love to see my competition sailing DDW...

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