Sailing

The Basics = Sailing Smart

by Jane Pegel - US 805

The experienced sailor has developed skills that enable him to have a great day of sailing and racing in a variety of conditions. This sailor (I am avoiding using "he") has the ability to select an appropriate ice site, appropriate ice site, properly rig the boat for the conditions of the day, and then properly handle the boat under sail. Past newsletter articles have addressed ice conditions, others have addressed tuning, but few have addressed the basic principles involved in becoming a good iceboater. Good iceboaters sail smart. My goal here is to discuss some of the factors to be considered if you want to sail smart.

One would think that just plain common sense would cause a sailor to sail his boat in a manner appropriate for the conditions. But my mother was correct when she used to say, "People can find more ways to try to kill themselves."

In Parking Areas

Hardly a day on the ice goes by that I do not see someone looking for trouble. First of all, don't bring your pre-school age child down to the ice without a crash helmet on his head. A toddler has difficulty walking on bare ground, don't put him on slippery ice. Likewise with your family dog. A child old enough to use ice skates should be brain washed about being around iceboats. He should understand that the iceboat cannot stop quickly. Designate a safe area for skating and stress the importance of his staying in that area. And I'm not pleased when an ice-skate creases the side of my boat when its wearer crashes and bums.

Whenever your boat is left unattended, be sure she is parked into the wind and the parking brake is on. It is also a good idea to pull the mainsheet line out of the aft blocks in case the wind shifts. DN rules require use of the parking brake.

Care must be taken when maneuvering in a crowded parking area. Whatever you do, DO IT SLOWLY. Pushing or pulling the boat should only be done in a direction straight into the wind. If you must head across or down wind, GET INTO THE BOAT so you have maximum control and visibility. Don't ride on the runner plank, sitting or standing. If a pedestrian, skater, or boat unexpectedly crosses your path, your maneuverability is limited when you're tiding on the runner plank. Don't park your boat in a high traffic area. As provided in the racing rules, a good race committee will establish a safety zone down wind of the finish line. This provides for a clear "sail out" zone after boats cross the finish line. Boats and gear parked in the safety zone may be disqualified.

Finally, when there is a good breeze blowing, hoist your sail after you have pushed the boat clear of a crowded parking area, and lower it prior to returning.

Turning and Stopping

Rocketing down the ice is the ultimate iceboating thrill. But how do you stop the darn thing? Or how do you turn the race mark when you're approaching it at warp speed? Let's take a look at the boat handling skills involved:

Stopping: Almost everyone knows you have to arm into the wind to stop. But not everyone knows the steps in the transition from rocketing to stop. The ultimate stopping challenge is on hard ice with a strong wind. If you're sailing on-the-wind, merely head into the wind and allow enough space for your speed to, "bleed out". If you're sailing off-the-wind at top speed, head straight down wind with your sail trimmed hard, this will allow you to slow down as the wind passes by your sail. The next step will be to turn across the wind (onto a reach) and then into the wind. As you start to turn onto the reach, ease the sail well out so you won't be thrown into a hike. Keep your weight forward in the boat so there is adequate pressure on the steering runner. Quickly turn toward the wind. If you're having trouble getting the boat to turn toward the wind, trimming the main slightly will help pivot the boat into the wind. Then as you get into the wind, trim the sail to reduce the flogging of the sail, battens and boom. As you coast to a stop, resist the temptation to drag your feet on the ice. In a DN it's easy to swing your feet out of the boat, but if your spikes catch a flaw on the ice, you may break your leg.

Turning the Leeward Mark: You can apply some of the techniques described for stopping, but as you get headed on-the-wind after rounding the mark, just trim in and keep going. Because you're likely to be rounding with other boats, it is very important to remember the two key things of trimming the sail is to pivot the boat in the turn and keeping your weight forward to hold the front runner on the ice. The Gold Fleet sailor approaches the leeward mark at high speed, heads for a pivot point about 50 feet from the mark toward the side where the race committee stands. He (this is a generic term) momentarily heads down wind to bleed off some speed, then turns for the mark into a, "transition zone", with the sail eased enough so that the boat does not hike. In this final approach he is headed toward a point about 15 feet down wind of the mark. When he gets about 20 feet from this point, he starts the turn, and as he comes close to the mark he is already headed on-the-wind with the sail trimmed hard. This is the perfect turn. The exact ice and wind conditions and the presence of other boats always require instantaneous adjustments. As the Bronze Fleet sailor comes down to the leeward mark, his initial heading is usually too close to the mark, he has not provided for a "transition zone" and instead of being headed on-the-wind as he passes close to the mark, his boat may be in an uncontrolled hike, careening off to starboard, a hazard to himseft and to others.

sail_smart_1.jpg (26381 bytes)


Port tack layline?  Not likely!  Sail smart - think ahead!!


Photo by Lou Loenneke


Rounding the Windward Mark: This can be hazardous when it's windy and a number of boats are approaching the mark together. The goal is to round the mark and head off-the-wind at top speed without colliding with other boats. As you make the approach to the mark lean way back with the mainsheet in your right hand and your hand close to your chest. If the boat starts to hike, you can extend your arm and this will case the sail some. Try to keep your body aft to hold the boat down. Peel off around the mark, heading off-the-wind until the boat comes out of the hike. If you're strong enough, you can trim the mainsheet as the boat comes out of the hike. Keep a firm grip on the tiller. Stay in sync with other boats making the turn. When all runners are on the ice and the boat is tracking a straight line, then you might be able to put the tiller between your knees and trim with both hands, but please don't try this when you're sailing close to me.

The Right of Way Rules

We race under the rules of the National Iceboat Authority. These rules were developed in 1963 by representatives of each of the iceboat class associations. Prior to that time we encountered different rules in different regattas. You can imagine the confusion. The basic philosophy of the rules:

  1. gives the boat sailing on-the-wind right of way over a boat sailing off-the-wind;
  2. gives starboard tack right of way over the port tack when boats are sailing on-the-wind or both are sailing off-the-wind;
  3. gives each boat the right to slow down or maneuver out of a hike (leeward boat when sailing on-the-wind, windward boat when sailing off-the-wind);
  4. gives the inside boat the right of way when approaching and turning a mark (leeward boat when approaching the windward mark on starboard tack, windward boat when sailing off-the-wind, inside boat at the marks, the starboard tack boats at the leeward mark);
  5. requires a boat altering course to stay clear (tacking, jibing).

The "inside" exception is the port tack boat approaching the windward mark, who must give way to the starboard tack boat. A sailor who keeps in mind the basic premises will find it easy to make safe and smart moves on the race course.



The 1992-1993 season will be Jane's 46th season of iceboating and her 37th season in DN's. A quick scan through results of past years show Jane winning the North Americans twice has been runner up seven times. She has also won the Northwest Annual Regatta 10 times. As you might have guessed, Jane is just as fast on soft water. In fact, she has been awarded the Yachts Woman of the Year Award three times & Jane has served the DN Class as Commodore sail_smart_2.jpg (15050 bytes)


This article was originally printed in the December 1992 newsletter

The Racing Tack

by Ron Sherry - US 44
December 1998

Over the last few years, advancements in ice boat technology have radically changed the face of DN racing. For instance, the new bendy rigs have ushered in a new era of speed. However, they have also presented us with a new challenge in tacking…mast rotation problems. The following article details several techniques that have been developed by the masters of the sport in answer to this challenge, as well as some strategies for completing a smooth racing tack while maintaining speed.

The ultimate goal of a racing tack is to complete the maneuver as smoothly and safely as possible without losing speed. Before you tack, make sure there are no other boats in the area and that you have a smooth and snow free area in which to tack. To begin the tack, start turning the boat up toward the wind. Start the turn slowly with the main sheet all the way in. Keep the sail in tight and start to slide your body forward in the cockpit. When the sail tacks, lower your helmet to the cockpit floor in front of the seat back. To accomplish this, anchor your heels in the hiking rack and bend your knees to pull yourself forward. Having your helmet on the cockpit floor means you do not have to ease the sail as much to get your head under the boom and you can maintain greater speed through the turn. This trick also equalizes your weight over all three runners and gives you better steering, making for a smoother tack.

When the sail tacks, ease the sheet just enough to get your head under the boom. Continue to lay the boat off and push the boom forward and to leeward with your leeward hand. As you do this, ease the sheet and use your knees and your weather hand to steer. Usually the mast will rotate at just about the same time the boat goes up on a hike. Let the boat hike, slide your body back into position and ease the sheet slightly. The boat will then begin to come down from the hike. As it does, sheet the sail in hard. This will cause the boat to hike once more. Ease the sheet slightly and before the boat comes all the way down from the second hike, sheet it in hard again. This second hike will help you to accelerate back to top speed. Smoothly completing a tack using this technique will send you off toward the next mark with very little loss of speed.

If the mast does not rotate using these techniques, do not lay off and pump the sheet. Laying off assures you to lose distance to weather, as well as putting more pressure on the leech of the sail and less pressure on the front of the sail. This allows the front of the sail to luff and the luff curve ill keep the mast from rotating. If you try tacking the boat and the mast does not rotate, Jan Gougeon recommends that you head the boat up toward the wind and allow it to slow down a little. This Reduces the apparent wind pressure on the leach of the sail and will maximize distance to weather and minimize your losses. No matter which technique you use to rotate the mast, this first step is the most important.

After the boat slows down a little, lay the boat off slowly and push the boom forward and to leeward, while adjusting the sheet. There are many techniques for this maneuver, no one better than another; simply try each one and decide which works best for you. Chip Cartwright slides forward and uses his toes to rotate the mast. Mike O’Brien uses his shoulder. Some people kick the boom. I have had the most success by sliding my leeward foot back so I can press my knee against the weather side of the boom. I then use my leeward elbow against my leeward knee to leverage the boom over. The boom is connected to the sail, which is connected to the mast by the luff rope that is in the back of the mast. A mast that has not rotated has the luff grove to windward. By pushing the boom to leeward, it pulls the luff groove to leeward where it belongs.

The Europeans have developed a solid hound that is about four inches wide. The side stays are connected at the outside of this four-inch bar. When tension is placed on the weather shroud, the solid hound rotates the mast. Perhaps a Sarns’ triangle and U-strap put on backward with the bent wings toward the front would have the same effect.

Once you understand the dynamics of this issue, it is easy to come up with a solution that works for you. If you have any questions or comments, feel free to contact me at Composite Concepts. The phone number is 586-790-5557, the fax number is 586-792-3374, and the email address is c2concepts@msn.com.

Boat Speeds

by Bob Dill - US 3904 - February 1993

All sail boats have performance characteristics associated with their design, sailing conditions and the amount of wind. Like most of us I have been curious about how fast we are truly going on the ice. Last fall I bought a radar gun. It can accurately measure the speed of a DN about 500 feet away. Wind speed was measured with a Davis Turbometer. The following are some measurements we have made so far this year, mostly from the Gold Cup.

Making measurements of wind speed or boat speed is easy. What is more difficult is measuring the wind the boat experienced to attain a given boat speed and sailing angle. For the purposes of this discussion I estimated the wind speed the boat saw based on the range of winds I measured on my anemometer over an extended period of time.

At the low end of the wind range the boats will sail in winds as light as about 2-1/2 MPH. The down wind boat speed is about 10 MPH and the up wind boat speed is about 12 MPH. Peak running speed is about 14 MPH so when boat speeds get slower than 10 MPH the races degenerate into running races. Races sailed in the North Americans on Wednesday in 2.5 to 3.6 MPH wind had peak boat speeds of 15 MPH and relatively little running. Races sailed on Monday in slightly less wind had too much running.

By 5 MPH wind the peak down wind boat speeds are in the low 20's. By 15 MPH wind the down wind boat speeds are in the mid to high 40's. The peak speed we saw at the Worlds was 56 MPH in wind that was 15 to 18 with gusts into the low '20s. Peak up wind boat speeds in this wind were in the low 30's Even in 25 to 30+ winds a few weeks ago Peter Hill and Bob Schumacher were sailing in the high '50s on a deep down wind angle.

On a broad reach with the sail sheeted as much as the boat would handle Bob got up to 68 MPH. A limiting factor is that the balance of the helm is very dependent on how much of the sail is luffing. This resulted in the need for rapid and radical corrections with the tiller. When Bob let out the sheet at the end of his run the runner lifted completely and he dragged the stern of boat for 150 feet or so. The drag of the sail exceeded the weight on the front runner.

We measured a couple of high wind indicators that will be handy when you do not have an anemometer in your hand. At about 22 MPH the sails on a parked boat will start to flog (modern racing sails). At about 32 MPH the boat will start to hop backwards on a rear mounted break.

Suggestions for racing winds on good ice: Wind that dips below 2.5 will result in excessive running. 3 MPH should eliminate running by skilled sailors. Of course, on sticky/snowy ice higher minimum wind speeds are appropriate. On the high wind end, 25 MPH in regular gusts seems like a reasonable top speed for racing. The Europeans set 12 meters per second (26.8 MPH) as their upper limit.

In terms of performance on a race course, it looks like the best boat speed to wind speed performance is at low wind speeds. A 4 or 5 to l ratio is possible at 3 to 5 MPH wind. At 15 MPH wind the ratio is probably closer to 3 or 3.5 to 1. By 30 MPH wind the ratio is only about 2:1.

I am also trying to get some data on other types of iceboats. If you would like to help with this project please get in touch with me.

Putting Numbers on Iceboat Sailing Performance

by: Bob Dill
February 2004

While there has been no shortage of speculation on top speeds, ice boating has been a hard sport to put valid performance numbers on. My effort to get a proper perspective started in earnest with the purchase of a good quality radar gun in the early 1990s. That did a pretty good job at sorting out the velocity picture but did not say much about angles (see 1993 article: "Boat Speeds" on the DN website).

In our speed project with the Wood and Iron Ducks on dirt we have evolved from using timing traps to radar and are now using a sophisticated GPS.  The GPS method has the significant advantages of allowing the freedom to sail wherever the wind takes us the fastest and avoiding the risk of having to sail fast at a measurement station.  There is more information on speed measurement on NALSA.org (particularly the Speed Record pages and the 11/99 newsletter).

The GPS we are using is a Trimble AG 132 with a Trimble data logger borrowed from a friend who works for the company.  This system is by far the most accurate and comprehensive system for velocity we have found.  The fixed position measurement uncertainty of the AG 132 (with the filtering turned off) is only 0.03 mph!  I also have done careful time over distance tests and found the GPS accuracy is at least as good as my test methods.  It's main liability is that it is expensive (it is a $4,000 GPS) and it is relatively bulky.

For projects other than setting speed records an inexpensive GPS with a data logging system is a good solution.  These units are surprisingly accurate.  The 0.1 mph accuracy claimed by most units seems to be valid most of the time based on comparisons of logs recorded simultaneously on the AG 132 and several Garmin hand-helds (see discussion of spurious data below).

Finding a good logging system was a problem until I found Kjeld Jensen's Cetus GPS logging software for Palm OS PDAs (cetusgps.dk).  It is free, easy to use and very well thought out.  Cetus collects the following data every one or two seconds (depending on the GPS).

  • Position
  • Time
  • Velocity
  • Bearing
  • Satellites in view
  • HDOP (the quality of the view)

Using a conversion utility from the Cetus site you can convert the Palm database format to a text file that can be loaded into a spreadsheet.  The simplest and one of the most informative things to do is to graph the velocity.  With a little effort you can identify the various maneuvers associated with velocity changes.  It is an eye opener to see how much ground is lost in a tack.

You can also do the trigonometry of the positions and do an XY graph of position to show the track of the yacht.  This gives a nice perspective on the angles, speeds and distances.

You can go through the numbers in the spreadsheet and find the tacks, jibes and roundings by changes in bearing.  From this you can calculate the cost of the maneuver in time and distance.  You can also calculate the true wind angle by averaging the bearing on each leg.  With that and a reasonable estimate of the true wind velocity you can calculate the whole velocity triangle (I do it on a cadd program and avoid the trig).  Beta (β) is the angle between the apparent wind and the yacht vector.  It is a good estimate of the efficiency of the yacht.

You can compare the results from yourself and your tuning partner or the whole fleet... there is just no end to how much time you can spend winnowing out information from this data.  However, no GPS data is necessary to know if you are going slower or not pointing as well or, most of all, not getting to the finish line first.  What the data does do is put numbers on what is otherwise obvious.  I doubt this data analysis will offer any shortcuts to the NA championship.

From the DN data in medium winds strengths, the speed loss in the tacks is about 7 mph (out of 32). This results in distance losses averaging 130 feet involving about 30 seconds between when the boat starts to slow and when it is back up to the pre-tack speed.  For a jibe in these conditions the distance loss is about half as much.  On a big race course in a big fleet there are lots of other factors to consider as evidenced by the tactics of the best sailors who often demonstrate the benefits of a couple extra tacks.

The apparent wind/yacht angle (β) is where iceboats, and particularly Skeeters, are King. The apparent wind angle (β) is surprisingly low for very efficient boats like Skeeters (6 to 7 degrees).  This is equivalent to sailing at 8 to 10 times the wind speed and they are, in fact, capable of this feat in light winds on good ice.  In DN's and fast dirt boats β is more like 10 to 12 degrees.  

Data Quality and Accuracy

When everything is working right, GPS's are very accurate relative to most other measurement methods.  The larger issue is that they can give spurious data when things are not working properly.  Usually spurious readings are outside the believable range, but not always.  The two most common reasons I have encountered are weak batteries or a poor and/or rapidly shifting view of the sky.  Filtering can also be an issue. Particularly at lower speeds or when there are abrupt changes in direction or speed.

A fresh set of batteries is well worth the minor cost involved.  Lithium batteries have long life, do well in the cold and are a bit more expensive.  For a reliable sky view, I have had mixed success with carrying the GPS in a pocket on top of my chest.  Side pockets are often not good enough.  The best place is securely taped to the deck in front of the mast.

The "Max Speed" function is convenient and generally accurate but it is a single point with no supporting data.  If you log the data you have a better basis for confidence in the top speed values.  As a point of perspective for a DN: speeds a little over 70 mph are possible but not likely.

Filtering helps a GPS make the best guess in a tricky situation.  It is also used to keep the unit from being confusing  For example manufactures don't want you to think that your GPS is moving when it is standing still so they filter out low speed readings.  This is called 'Show Room Mode'.  'Tunnel Mode' tells the GPS to hold a reading for a few seconds when the signal goes away.  'As you were mode' tells the GPS to keep doing what you were doing.  This shows up sometimes when there is an abrupt change in velocity or direction.  While filtering causes some velocity errors these units do a remarkable job of telling you where you are and how you got there.  When these errors do occur they are generally obvious when you look at logged velocity data.  

Unlike inexpensive units the Ag 132 can be configured to turn the filtering off.  This allows measuring the fixed position 'speed' which is really the measurement error.  This is valid for both a static or moving GPS because the satellites are moving at several thousand mph relative to the GPS.  From their standpoint the GPS is moving very quickly at either 0 or 100 mph.  

Spotting Errors In Logged Data

Most of the times I have found bogus data it is related to a poor view of the sky.  The following are several things to look for:

  • If the number of satellites is below about 6 or the HDOP is over 3, the view of the sky may be a problem.
  • Calculate the accelerations and if they are more than -15% or +8% of gravity the data may be bogus (more simply if the speed decreases by more than 6 mph or increases by 4 mph in a two second interval you may have bogus data or the boat did something memorable like spun out).  The biggest speed changes occur during tacks or rounding the leeward mark.
  • Look for unchanging speed values.  More than two identical values is suspect.
  • Look for unrealistic speeds, time gaps, etc.  All of this can be done with simple spreadsheet functions.
  • The velocity = f(time) plot is a quick way to spot dubious data.

Hardware

You need a GPS, a Palm Operating System PDA (you do not need much memory as the Cetus track.pdb files are very efficient), GPS data and PDA hotsynch cables, a null modem connector and a gender changer (Radio Shack).  Duck tape, packaging tape and/or a velcro covered cloth bag are helpful for mounting the GPS in a convenient place with a good view of the sky.

I have used several GPSs.  I like Garmins but they all have a 2 second time interval for NEMA sentences (data output).  I recently got a Magellan Meridian Gold mapping GPS at Costco that will output at one hertz.  Two seconds, however, is fast enough to get a good understanding of most of what is happens on an iceboat.  I keep hoping that the GPS makers will combine a Cetus like logging program into their vast computational capacity and memory.  Several requests for this have, so far, gone unheeded.  The track log on my Magellan will put in data points every second or so at speeds above 40 mph but the speed data is inaccurate.  There is a one second swing in the velocity averaging about 2 mph (ranging up to 7 mph) when the boat was going at nearly constant speed.

Software

You need to know your way around your GPS setup, the PDA and the Cetus software.  Cetus has an excellent guidebook on their site.  It may take a little trial and error but it is pretty straightforward.

As you get data that you feel are representative of different circumstances I would love to see it.  In spite of logging data for three seasons I have yet to get good data for racing in winds over 20 mph or reasonably pure light wind sailing.  My email address is rdill at verizon (dot) net (spaces and spelling are an attempt to dodge email address crawlers should this newsletter find its way onto a website).

Happy Data Logging,
Bob