Just how many times should a curling stone rotate as it moves down the ice?
Ideally, during a delivery a stone travels – initially – down the line of delivery towards the target, with a rotation applied by the wrist just prior to the release. On a draw shot, when the stone reaches the other end of the sheet, both its forward travel and its rotation cease simultaneously.
In the most recent OCA Blue Challenge booklet for junior curlers, Challenge #2 (Consistent rotations) calls for:
- The curler is to deliver 6 draw stones with 2 to 4 rotations.
- Little Rock curlers may have 2 to 5 rotations.
While at the Team Glenn Howard fantasy camp in early October I asked lead Craig Savill about his experience with stone rotations. Craig felt that fewer than two rotations was inadequate, particularly on curling club ice where there may be sufficient frost on the ice surface to cause the stone to lose its rotation, resulting in an unpredictable path. Conversely, in Craig’s experience more than three rotations was too much – three or more rotations cause the rock to run straighter. Craig’s views dovetail exactly with the views of former National Training Centre coach Bill Tschirhart, who in his latest book [1] writes:
A stone that rotates less than 2 rotations is unpredictable. It may curl. It may not curl. If it does curl it may not curl the amount expected. It may slide. It may “dig in”. Well, you get the picture I’m trying to paint I’m sure. On the other hand, a stone that rotates more than three rotations tends to run straighter than normal (sometimes a desirable situation). But a stone that rotates about 2.5 rotations will “perform” according to the manufacturers’ specifications. It will “finish”.
Our goal, then, should be to deliver granite stones with 2.5 rotations. To satisfy the Blue Challenge, junior curlers are given more leeway: 2-4 rotations (2-5 for younger curlers throwing Lite Rocks). What I don’t know – but I will try to find out – is what the optimal number of rotations is for a Lite Rock stone. In my experience at Elmira, two rotations with a Lite Rock stone seems too few, but I don’t know what the “best” number is.
[1] Bill Tschirhart (2010). A Pane in the Glass: A Coach’s Companion. Corporate Imaging Centre, London, Ontario. ISBN 978-0-9866513-0-4.
Today I discussed rotations with Kim Tuck of Canada Curling Stone, who herself curls in Grand Slam events as a member of the Jacqueline Harrison rink. Kim informed me that Lite Rock stones are designed to completely mimic granite stones, and so young curlers should also aim for 2 and 1/2 rotations with Lite Rock stones, just as adults should aim for 2 and 1/2 rotations with granite stones.
Now that stones and ice are being prepared to curl more in the competitive game, rotation of 4-5 is becoming the norm. A player learning to vary the throw from 3 to 5 rotations depending on the ice and stones has become a skill to master, along with a very positive release.
Thank you for your comment, Jean – it has been a long time since I posted that article (ten years) and collectively we know quite a bit more about curling stones and trajectories than we did in 2010. Two comments in response: one, I don’t disagree that varying rotations is an important skill to acquire, but in my work with Juniors and university athletes I’ve found it challenging simply to get athletes to throw with the same release consistently (both in-turn and out-turn). I’ll publish another article to that effect in the next few days. Two, our research of tour teams indicates that (a) unsurprisingly, the better teams tend to throw consistent rotations amongst their players than other teams, and (b) there is a wide distribution of how many rotations are thrown for the same weight amongst the various teams. Rachel Homan’s team, certainly, is a team that is frequently pointed out as a team that throws with more rotations than others – but not only are they not the only team to throw more rotations than average, there are other very successful teams that throw with fewer rotations because it suits their practice of rock management for their particular team.