Curling Quandary: Why Stones Curl the “Wrong” Way

Brian Handwerk
for National Geographic News
February 23, 2006

David Murdoch of Great Britain follows his shot during the February 22 semifinal men’s curling match between Finland and Great Britain during the 2006 Winter Olympic Games in Turin, Italy. Photograph by Ian Walton/Getty Images

Canadian physicists may have answered a question that’s been around for curling’s entire 500-year history: Why does a curling stone curl in a direction that seems contrary to the laws of physics?

Interest in curling is enjoying a growth spurt, highlighted by this winter’s Olympic competition in Turin, Italy.

Tomorrow Canada battles Finland in the men’s gold-medal game, while the United States men’s team goes for a first ever curling medal in a bronze matchup against Great Britain.

But even with increased attention to the sport, many athletes and fans have been largely unaware of one of curling’s biggest quandaries.

In the modern version of this ancient Scottish game, competitors slide 42-pound (19-kilogram) “stones” or “rocks” down a clean sheet of ice. Each team hopes to place its own stones closest to the center of a bull’s-eye target known as the house.

Spin is a crucial part of every shot. Olympic curlers generally try to spin the stone the same way each time—three rotations from the start of a shot to its finish.

“The spin actually makes the stone go to a specific spot,” said Shawn Rojeski, a member of the U.S. Olympic Curling Team from Chisholm, Minnesota.

“When we put the spin on it, one way or the other, we’re more or less guiding in which direction we want the rock to go.

“If you were to throw the rock with no spin, it would be nearly impossible, and it would be hard to control where it goes,” he continued. “Any little feature on the ice would make the rock change direction.”

Sliding Surprise

But when University of Northern British Columbia physicist Mark Shegelski took up the game, he noticed that the spinning stone curled, or moved to one side, in a counterintuitive direction as it slid down the ice.

Shegelski often demonstrates the problem to curlers after a game.

“I take a nice drinking glass, rotate it counterclockwise, and slide it down a counter,” he said. “Everyone thinks that it will go to the right. That’s the natural reaction from curling.

“But it goes to the left, and the initial reaction [from curlers] is that I’m performing some kind of magic trick.”

Indeed, Olympian Rojeski did not know that his expert spins present an apparent physics mystery.

“I’ve never sat down and thought about it,” he said. “I bet if you talk to the average curler, nine out of ten people would be unaware of it.”

So why does the stone curl the “wrong” way?

Shegelski believes that the answer lies in wet friction, courtesy of a thin layer of meltwater that temporarily forms under the stone.

But testing his theory presented its own share of problems.

“When I’m talking about a thin film, I mean a really thin film” of meltwater, he explained.

“There’s no way to measure it directly. If you turn a curling rock on its side, you’re not going to see” a puddle on the ice.

Lacking a way to observe the watery film, Shegelski and fellow physicist Erik Jensen recruited volunteers at their local curling club and created a precise under-ice grid system to help track the stones’ movement.

They then filmed a variety of shots from an overhead angle using a suspended video camera.

Their data provided a likely explanation.

When a glass or other spinning object slides along a surface, its forward edge holds the highest frictional force.

Thus, when a moving stone is rotating clockwise, it’s front edge moves to the right. Sideways friction should cause the object’s path to angle, or curl, to the left.

But that extremely thin layer of melted water changes the effect of friction on the stone. It creates better lubrication, and therefore reduced friction, at the front edge.

The sideways friction on the stone’s rear edge—where the meltwater has already refrozen—dominates the stone’s curl instead and makes it move in the opposite direction.

The results are experimental—they don’t definitively prove that meltwater is creating wet friction responsible for the stone’s spin.

But theories that don’t involve wet friction seem unable to explain the experimental results.

Enduring Mysteries

John Williamson, a retired ice technician from Clintonville, Wisconsin, knows the science of the sport as well as anyone.

For years he prepared ice for curling matches by tracking a myriad of variables, such as humidity levels, dew points, and temperatures at different positions all over and above the ice.

He also prepared surfaces with tiny drops of water called pebble, which are sprayed on the ice to control friction.

Williamson believes the friction created when the stone moves over the pebbled surface is key to creating the meltwater and subsequent asymmetry that is responsible for the stone’s unusual trajectory.

“If Jenson and Shegelski are right—and I think they are—what makes the rock curl [the 'wrong' way] is that asymmetry,” he said. “There’s meltwater at the front of the rock and not at the back.”

Williamson explained that, among those curlers who did ponder the reasons behind the curl, the research was welcome.

“There were a lot of arguments going on, because after 500 years nobody could totally understand why these stones curled as they did,” he said. “Nobody could get it down to a science.”

Shegelski has returned to his day job studying quantum mechanics, leaving some curling mysteries unexplained.

“It’s hard to understand why curling rocks curl as much as they do,” he said.

“If they only curled half as much it wouldn’t be hard to understand. There’s at least one mystery that I don’t think we’ve found the answer to.”

© 1996-2006 National Geographic Society.
All rights reserved.

This is a duplicate post with an entry on the Light The Torch blog … in case you aren’t reading that blog .. oh – you should! you should!

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I mentioned in an earlier post titled “Greetings From The Curling Tag” .. that there are 13 “NOC”‘s (National Olympic Committees) competing in Olympic Curling games.

Here’s a little more “Curling 101” information that might be of interest to you!

* There are 13 NOC’s competing in the 2006 Olympics. They are:

CAN – Canada; GBR – Great Britain; ITA – Italy; NOR – Norway; SUI – Switzerland; SWE – Sweden; USA – United States

The above 7 countries have both Men and Women’s curling teams competing. In addition to that, there are 3 additional countries / NOC competing so each Men’s and Women’s have 10 teams in the Round-Robin competition.

FIN – Finland; GER – Germany; NZL – New Zealand; … have Men’s Curling teams
DEN – Denmark; JPN – Japan; RUS – Russian Federation; … have Women’s Curling teams

* Generally, there are 3 sets of starting times for all games throughout the competition …

09:00 Local time (2:00am ET)
14:00 Local time (8:00am ET)
19:00 Local time (1:00pm ET)

If you look at the schedule listing, it starts off with the Men’s curling teams taking up two of the time slots (first and last) and then the Women’s curling teams taking up the middle time slot. This pattern is alternated through out the event, where tomorrow the Women will have two time slots and the Men’s only one time slot .. until the Tie-Breaker matches starting February 21, 2006 .. and other medal matches up to February 24, 2006.

Today’s Schedule – February 13, 2006 Schedule

09:00 (local) MEN’S CURLING
NZL vs SWE
ITA vs GBR
NOR vs USA
FIN vs SUI

14:00 (local) WOMEN’s CURLING
NOR vs USA
CAN vs SWE
SUI vs ITA
GBR vs DEN

19:00 (local) MEN’S CURLING
GER vs CAN
FIN vs USA
GBR vs NZL
ITA vs SWE

The schedule can be found HERE.

Some Other Curling Basis

* The object of the game is to throw your stones as close as possible to the target area in the “house”
* The skip decides on the strategy, and throws last in each end
* Despite any controversy, Russ Howard of Team Canada Men’s team (who throws second) calls the strategy in the house and has final call on all other rock. Brad Gushue has final decision on his own rocks and Team Canada is “Team Gushue” rink!
* The third often assists the skip in making strategic decisions
* The players must release the stone, when throwing, before the red “hog line”
* The official curling rink is 44.5 m (146 ft) long by 4.75 m (16 ft) wide
* The players CANNOT sweep opponent’s rocks between the hog line and the front of the house target (called the Guard Zone)
* Also, the Lead and Second players cannot remove opponent’s rocks in the Guard zone either
* Only stones inside the rigns of the house counts as points, The team with the one closest to the center scores a point for every other stone closest to the the center before the opponent’s closest stone
* The stone is made from granite, controlled by a handle, and weighs 19.96 kg (44 lbs maximum). It’s diameter is 30 cm (11.8 inches)
* The path of the rock is swept clean to control it’s projectory, and brushing “Haaaaardd and Haaaaaarrddder’ will most likely make the ice faster or slicker
* Brushing on one side of the stone helps create its ‘curling movement’ towards that side of the rock
* Some argued that those old “whap-whap-whap corn brooms” (my brother’s favorite!) creates a vaccuum and sucks the stone further along the ice.
* Great Britain’s curlers are introducing secret “State-of-the-Art” brooms completely loaded with sensors and a memory card, called the “sweep ergometer’ (i believe) which is supposed to measure how well the team is performing under crucial tasks .. That should be interesting to watch!

Source: Around the CBC site and Curling Blog site

Sports News Article | Reuters.co.uk – Brits win curling gold — 82 years late

Thu Feb 9, 2006 9:36 PM GMT
By Rachel Sanderson

TURIN (Reuters) – British curling swept to a gold medal on Thursday — the day before the Winter Olympics were due to open — after sleuthing fixed an 82-year-old injustice.

The International Olympic Committee (IOC) said it had decided medals presented to four of the country’s curlers at the first Games in 1924, when the sport was believed to have been only a demonstration, deserved official status.

A Glasgow newspaper persuaded the IOC to fix its oversight after it followed up evidence discovered in the Royal Caledonian Curling Club’s records.

“We have always been aware that our sport had a great history and we knew there had been curling in 1924,” World Curling Federation president Roy Sinclair said.

The posthumous win for Scottish curlers Willie and Laurence Jackson, Robin Welsh and Tom Murray gives Britain its second Olympic curling gold, to follow victory four years ago for a Scottish quintet in Salt Lake City.

Members of this year’s team, who are medal outsiders here, said the surprise 1924 upgrade had not given them a special boost.

“It’s nice, but I don’t see it as an omen,” Euan Byers, lead on the third-ranking men’s team said. “Success comes from ability and a bit of luck.”

Scottish housewife Rhona Martin pulled off a dramatic victory four years ago with a last throw in the final game against Switzerland that gave the nation its first winter win since Jayne Torvill and Christopher Dean’s Bolero ice dance in 1984.

Curling — where players use brooms to clear the path for a stone across an ice rink — was treated as a demonstration sport five times in a row before finally being granted medal status in 1998 at Nagano, Japan.

© Reuters 2006. All Rights Reserved.

Tyler Morning Telegraph – SPORTS WIRE – 2006 Winter Olympic Preview: Curling

01/24/2006

(Sports Network) – Although the sport of curling dates back to the early part of the 16th century in Scotland, it didn’t become an Olympic medal sport until 1998 in Nagano.

Sometimes compared to shuffleboard, curling is played by sliding heavy stones on ice. In the 16th century those stones, which now at regulation weight are 42 pounds, were used on frozen ponds, lochs and marshes. Unlike other winter sports such as skiing, luge, figure skating or speedskating, curling has organized clubs. The sport has been enhanced by the friendships that are formed throughout several competitions.

Curling takes place between two teams with four players on each squad. The game is played on ice, and the two teams take turns pushing the 42-pound stone towards a series of concentric circles. The object is to get the stone as close to the center of the circles as possible. The center of the circles is known as the “tee.” A team scores a point for each stone that is closer to the center circle than the opponent’s best stone, provided that the stone is within six feet (1.83 meters) of the tee. This circular area is known as the “house.” It is the scoring zone in curling. A game is made up of 10 ends, just like innings in baseball. The basic components of the 500-year-old ice sport are delivery of the stone, sweeping along its path, and strategy.

Special brooms are used to sweep the ice for friction to create more or less speed for the rock. The skip on the team is probably the most important player. That person holds the broom as a target for shots by the other three players. Skips are team strategists and must study the ice, judge the amount of curl, and call the shots. Skips usually throw the last two rocks of each end. The men’s and women’s tournaments will consist of 10 teams each competing in a round-robin tournament. During the preliminary series, each team will play against each of the other teams. Based on the results of the round-robin, teams will advance to the semifinals. The winners of the semifinals will play in the gold-medal game. The losers of the semifinals will play for the bronze medal.

The curling competition starts on Monday, February 13. The women’s bronze and gold medal matches are scheduled for Thursday, February 23, while the men’s bronze and gold medal matches are the following day. Curling will be held at Pinerolo Palaghiaccio, which is approximately 30 miles southwest of Torino. TOP CONTENDERS AND CURRENT CHAMPIONS Although the sport is probably most popular in Canada, the men’s Olympic titles have gone to Switzerland (1998) and Norway (2002). The Canadians have finished with a silver each time.

Pal Trulsen leads the Norwegians as the team’s skip and has led his squad to a fifth place finish or better at every world championships since 1999. The 43-year-old Trulsen, back for his third Olympics, is joined by teammates Lars Vaagberg, Flemming Davanger, Bent nund Ramsfjell and Torger Nergard. Finland’s Markku Uusipaavalniemi heads another potential international threat for men’s curling gold. His teams have finished no worse than fifth at the world championships since 2000. Wille Makela, Kalle Kiiskinen, Teemu Salo and Jani Sullanmaa are also on the Finnish men’s team. Ralph Stockli heads the Swiss men’s team, which also won a bronze medal four years ago.

In the women’s division, Great Britain claimed the gold in 2002, while Switzerland won the silver and Canada the bronze. The Canadians won gold in 1998. Rhona Martin skipped the British women to the title in 2002 and will return this year. She’ll be joined by Kelly Wood, Jackie Lockhart, Lynn Cameron and Deborah Knox. What may give the Brits an advantage is technology. They have reportedly been using state-of-the-art brooms that have a memory card and sensors. It’s apparently being used to review how sweeping forces of athletes can help the stone slide to the target.

UNITED STATES/CANADIAN OUTLOOK Canada stands an excellent chance at sweeping the gold in both the men’s and women’s divisions.

Brad Gushue skips the Canadian men. The 25-year-old’s team barely won the national championships in December. Gushue will be the youngest man to skip a Canadian team at the Olympics. He’ll be joined by Mark Nichols, Russ Howard, Jamie Korab, Mike Adam on this year’s squad in Torino.

Shannon Kleibrink, Amy Nixon, Glenys Bakker, Christine Keshen and Sandra Jenkins make up the Canadian women’s rink. Kleibrink, who serves as the skip, pulled off some upsets at the national trials. In fact, her team lost three of the first four matches before putting together seven consecutive wins to earn a berth in Torino.

The Americans have a daunting task if they are to medal in curling for the first time at the Olympics. The owner and operator of a pizza shop in his hometown of Bemidji, Minnesota, Pete Fenson will skip the U.S. men’s team. Fenson’s team came in sixth at the 2005 World Curling Championships after beating New Zealand, which qualified the squad for the Olympics. Also on Fenson’s team will be Shawn Rojeski, Joseph Polo, John Shuster and Scott Baird. For the second straight Olympics, the U.S. women’s team will be led by a sister tandem.

In 2002, Kari Erickson and her sister, Stacey Liapis, were on the team that finished fourth. This time, it’s Cassie and Jamie Johnson headlining the “Curl Girls” in their effort to bring home a medal. They’re joined by Jessica Schultz, Maureen Brunt and Courtney George.

©Tyler Morning Telegraph 2006

Copyright © 2001 T.B. Butler Publishing Company, Inc.

Copyright © 1995 – 2006 PowerOne Media, Inc. All Rights Reserved.

The Curling News: Curling uproar over 1924 Games

From the “Curling News” Blog

….. The IOC is now investigating: will the Scottish story prove to be premature… or not?

The curling world is in an uproar over The Herald’s claim to have exposed this 82-year-old Olympic sporting secret. As explained in the previous post, The Herald reports the International Olympic Committee has confirmed that gold medals won by Great Britain in curling at the first Olympic Winter Games (photo), held in Chamonix in 1924, are now genuine, and should no longer be considered demonstration medals.

However, an IOC official, who declined formal comment, told The Curling News that Olympic archivists have now been assigned to verify the facts, and will confirm the information tomorrow: We’re digging out the official 1924 program, the official said. It’s been 80 years, and we’re going to take another day to look at it.

The news, confirmed or not, has shocked the curling world. If the claim is verified, the gold won at the 1998 Games in Nagano by Canada’s Sandra Schmirler and Switzerland’s Patrick Huerlimann would no longer be the first official curling medals ever handed out in Olympic competition.

Click on the link at the beginning of the story for the full story and the rest of this article.

Scotland wins Olympic gold . . . 82 years later – The Herald

Web Issue 2448 January 23 2006
DOUG GILLON

A Scottish curling team has been designated Olympic champions more than 80 years after its victory on the ice.

It had previously been thought that the sport was a demonstration event at the 1924 Winter Olympic Games in Chamonix, meaning that winners would not be considered to be medallists.

However, after an investigation by The Herald, curling’s competitive status has now been confirmed by the International Olympic Committee, which should lead to Britain’s official gold medal tally increasing by one.

The revelation of the hitherto unrecognised victory was greeted with a mixture of delight and astonishment by the British Olympic Association, whose chief executive, Simon Clegg, said: “I am fascinated, and amazed that huge authorities on the Olympics have not picked up on this.

“I’m very grateful to The Herald. The history books will need to be re-written.”

The son of Robin Welsh, who was one of the team members, died on Friday before learning his father had won Olympic gold.

Grandson Peter Welsh, who now has the medal, says he and his father, also Robin, had believed like everyone else that curling was a demonstration event.

“I had been looking forward to telling him about the Olympic gold medal, but never had the chance.”
The other team members selected by the Royal Caledonian Curling club were Willie and Laurence Jackson and Tom Murray.

* Read the full story by Doug Gillon in today’s sports tabloid

Everybody must get stones

Saturday, January 21, 2006 – Bangor Daily News

You think Maine winters are bad? Consider 16th century Scotland. There were no big-screen televisions, no iPods, no Netflix. Forget central heat….

This is an interesting article and good reading (i.m.o.) … click on the link at the beginning of the article for a little history of curling and the Belfast Curling Club in Belfast, Maine..

About The Brier

About the Tim Hortons Brier

First presented by the Macdonald Tobacco Company in 1927, the Macdonald Brier Trophy was awarded annually to the winner of the Macdonald Brier until 1979.

Macdonald Tobacco withdrew its sponsorship that year after 50 years and the Macdonald Brier Tankard was retired.

When Labatt Breweries became the Brier sponsor in 1980, it introduced a gold Labatt Tankard, which became the icon of the Brier and was awarded 21 times. When Labatt decided to end its title sponsorship, the Labatt Tankard was retired.

When Nokia Products Ltd. became the Brier’s new sponsor, it decided in consultation with the Canadian Curling Association to reactivate the original trophy beginning with the 2001 Nokia Brier.

The trophy was restored and the base expanded by Clarkes Recognition Products of Vancouver.

For its first 27 years, the Tankard was presented with a sterling silver heart plaque attached to it on which the names of each team member had been hand-engraved. After 27 years no space was left, so a single plaque was attached to the back, where the names of all the winners from 1955 to 1979 were engraved.

Clarkes increased the size of the base so that a silver heart crest could be attached for every Brier-winning team.

The Nokia Tankard now proudly displays a hand-engraved silver heart for each of the 72 Brier winners.

The original cup on the trophy was hand-tooled in Great Britain and is a work of art that could be re-created only in Europe. The replacement value of the original trophy has been estimated at $17,000. The CCA invested $10,000 to complete the restoration.

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The 2006 Tim Hortons Brier
March 11-19, 2006
Brandt Centre, Regina, SK
Web Site: www.timhortonsbrier.ca

www.curling.ca/championships/brier/index.asp

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Copyright © 2005 Canadian Curling Association. All Rights Reserved.