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Rocks are timed for three reasons:

  1. Measure and monitor ice conditions
  2. Measure shots as they are moving
  3. Calibrate (dial-in) shots

Each reason will be discussed in this section.

How it Began 


Using a stopwatch to time rocks began in the 1980's as a way to measure the speed of the ice.This helped teams play at different clubs where the conditions could be different.It also helped measure “tracks” on the ice during the games.Keep in mind that the ice conditions up to this point were fairly crude compared to today's standards.The original timing method was long times, from the hog line to the tee line.Conditions were slow (20-23 seconds - 12.0 to 12.5 by today's hog to hog standards) but consistent.As ice conditions improved through better water quality and the invention of the ice scraper, the need to measure conditions increased. In the early days of timing the split time did not exist.

The Free Guard Zone rule (4 rock to 5 rock) made timing more difficult since there were more rocks in play.The five-rock rule essentially made long times obsolete, and the new ice measurement timing standard is hog to hog.This eliminates the issues of too many rocks in play.

There are two main reasons to time rocks:

  1. Measure the speed of the ice (measuring conditions).
  2. Measuring the shot to assist decision-making (sweeping) during a shot.

The Timing Concept 


Time a rock from the time it crosses the near hog line to the time it crosses the far hog (and stops on the tee line).A typical time for a draw on normal ice is between 13.0 and 14.5 seconds.It is not player specific since the rock has already been released.It can be used with all four players.

The higher the number, the faster the ice (14.5 seconds represents faster ice than 13.5).

This is counter intuitive.The terms fast and slow refer to the ice conditions and not the rock speed.

This might help:
Imagine trying to throw a rock ten feet on a concrete surface.Because of the rough surface of concrete, the rock would quickly decelerate, and you would have to throw the rock extremely hard and fast to cover that distance.As the rock travels over the concrete, it slows down rapidly and may only take one or two seconds to come to rest.Now imagine throwing the rock the same distance (ten feet) on ice.Since ice is much smoother and slicker than concrete, much less energy is required to move the rock ten feet.This rock is actually moving slower and traveling for a longer period of time.It may take five or six seconds to come to rest.

In the early ends of a game, the ice may be a bit frosty or may have a fresh pebble.This means more friction, similar to the concrete example above.As the game continues, the pebble slowly wears away and the sweeping removes most of the frost.The ice gets faster as the game continues.Draw times at the beginning of a game may be 13.0 to 13.5 seconds.This will most likely increase to 14 or 14.2 seconds toward the middle ends.Be careful not to assume that the ice is the same speed in all areas.A faster track is created down the center of the sheet.An area approximately three feet on either side of the centerline is usually faster than the outer edges.The reason for this is most rocks travel down this fast-track area.It is also caused by the polishing of the ice resulting from sweeping and by the polishing action of the sweeper's shoes.Shots thrown on the outer edges can be a second slower than the center track.In the later ends however, the fast-track area begins to flatten-out due to the number of rocks, footwork and sweeping.This leads to a slower area called a flat spot or fudge spot and the ice gets slower.This happens sometimes in longer, more competitive games.

As a sweeper, don't try to judge draw weight from times alone.
Timing helps judge relative ice speed.It helps you respond to changes in the ice surface during a game.It also helps you judge ice speed at other clubs relative to your own club.As mentioned in the Sweeping Section, try to get a “sense” of draw weight first.Use stopwatch times to enhance your skills.



Measuring the Conditions

Like most other sports, measuring conditions is an important part of curling.Many curlers can measure the speed of the ice simply by feel and experience.The body's kinesthetic sense of movement and spatial skills can provide a minimum degree of speed judgement.Most curlers can throw basic draws and takeouts on ice without a formal measurement system.In general, you may be able to determine how fast or slow the ice is compared to your club and to judge relative changes in the ice speed throughout the game.

Adding Science
Players will agree that a more precise way to measure the ice speed is essential for team performance.The speed of the ice can vary greatly from club to club and vary between games and within a game.Constant assessment is necessary.Timing shots will help you with a more exact measurement.

There are two reasons why a timing system is helpful.Ice conditions change over the course of the game due to several factors.Pebble wear is the main contributor.Moisture settling in the form of frost is the second.At the beginning of the game, the ice has been freshly scraped, pebbled and nipped.As the rocks travel over the surface, they continue to break down the fresh pebble.The nipper helps cut the pebble for but does not completely break down the pebble.Early in the game, the highly traveled paths get faster in speed.Timing rocks will allow you to see speed changes in different rocks paths.

At the end of the game, the reverse happens.The high traffic paths begin to flatten causing rocks to slow down or check-up.

To measure ice conditions:
Players time draw shots in three different ways, long times (not used much anymore) hog-to-hog and interval times.

  • Long times (hog to stop at the tee line, 24.0 seconds)
    Long Times were the original ice assessment tool and are still useful.However, many competitive curlers have switched to hog-to-hog times.
  • Hog To Hog Times
    Values of 12-13 represent slower conditions while 14-16 represent fast conditions.HTH times may be beneficial for the following reasons:
    • Skips can easily time rocks without being distracted by rocks in play.
    • Skips can assess rocks in real time (after the hog line) and communicate to the sweepers.
    • It is useful to track ice speed over time and on tracks.
  • Both long times and hog to hog times assume that the rock will stop on the tee line.
    If measuring the ice speed, this is important.It is not the best sweeping tool since the shot is nearly complete when it reaches the second hog (or the tee).
  • Split Times (interval)
    Split times remain the best tool for sweeping judgement.Standard times are 3.75 - 4.00 for draws and 2.90 - 3.10 for normal takeouts.Split times provide the earliest information for sweepers, and they can react immediately with actual numbers.



Measuring the Ice

Timing Hog to Hog
The skip is responsible for managing the ice conditions.All team members can take HTH times including the skip.Sweepers can take HTH times, especially if they use one primary sweeper.The other sweeper can easily take the HTH.With the proper stopwatch, they can take the split time AND HTH on the same watch.Sweepers can help with HTH times by timing opponent's rocks as well.

Hog to Hog Tricks and Traps (HTH)
Timing ice conditions using the HTH method, although not useful as a sweeping tool, have a short "in the moment" component (as opposed to NO in the moment benefit for long times).For example, a draw that is timed to the hog line still has another twenty feet or so to complete.Knowing the HTH time can help sweepers and skips finish a shot. The HTH times also take the delivery inconsistencies out of the equation.These times are good for developing team weight consistency and are good feedback source AFTER the shot.Hog to hog times tell you what was as opposed to short times that tell what is.If your team is looking for immediate, real-time feedback, the short time is best.

Use HTH times as a confirmation of weight on both draws and takeouts.

Hog-To-Hog Sweep Coefficient
Timing rocks to understand how ice conditions affect your shot is a very effective tool.Consider the following.A HTH time of 14.5 is not uncommon on faster ice.In order to fully understand this number, the external factors surrounding the time must be understood. Using HTH times to measure ice conditions is generally thought of as the time it takes a rock between the hogs - and stopping on the tee line.The coefficient or multiplier in the equation is the amount of sweeping applied to the measured shot. A 14.5 unswept is very different from a 14.5 fully swept.

As a player, you and your teammates must define the coefficient for the times to be useful.As a team member, relaying HTH information must be consistent.A good rule of thumb is to define the coefficient as 50% swept since it's rare that a shot is either not swept at all or swept the entire way. Setting the coefficient other than 50% swept would be unreasonable since the times can vary from 14.2 unswept to 14.8 fully swept.By communicating the speed as 14.5 puts you and your team in a much better position.



Measuring the Shot

Short Times/Splits
Interval timing is a scientific method that helps sweepers judge weight.A designated sweeper can time a shot between two points, usually the back line and nearer hog line.This split is the time it takes the rock to travel from back line to hog line and will indicate its ability to make it the rest of the way.This is a relative measurement.The time that is measured cannot be easily calculated into a long time due to the deceleration of the rock.The times can be used as a reference.

As rock timing evolved, split times or short times were incorporated and used as a sweep judgement tool.Short times are great for immediate feedback on any given shot.They can be used to make decisions as shot is happening. Typically, a short time is the time a rock travels from the back line to the nearer hog line. Draw numbers like 3.85 seconds and 3.95 seconds are common for draws on normal ice.Sweepers can use these times to help judge weight (live).Because of different delivery types, short times can change by player.For short times to be a good ice speed tool, all deliveries need to be consistent.We prefer using longer times to judge conditions and let the sweepers use short times as a sweeping tool.

Using short times as a sweeping tool is very effective.It is also discussed in the Sweeping Section.

Split times are used by sweepers and have a small ice speed component.In the hack, the thrower could look to the sweepers and say, “is the ice still running 14.2”.This will help the thrower judge ice speed as the ice may be changing.They can also say “what are you looking for?”The sweepers will respond with a target short time, 3.80 for example.This may not be necessary for every shot.If the conditions are constant (middle ends) it is not necessary to ask.A good, trusting team will know if the conditions are stable.If not, the sweepers will tell the thrower what a new target split would be.

Back to Hog Split Example
When throwing a draw on 14.5-second ice, sweepers will look for a 3.95 second draw split (time from back to hog).If the sweeper clocks a 4.10 second split, it is likely to need sweeping because the rock is traveling slower (it took longer).A 3.70 second split will probably not need sweeping.

The following is rough example of split times a sweeper will look for on draws.

Ice Speed Hog -Tee Ice Speed Hog-Hog Split Target
23 seconds 13.5 3.70
23.5 seconds 13.8 3.55
24 seconds 14.0 3.80
24.5 seconds 14.2 3.85
25 seconds 14.5 3.95
25.5 seconds 14.8 4.00
26.0 seconds 15.0 4.10

Using standard splits for all team members is dangerous.This will only work is the deliveries are exactly the same.In most cases, teams will have multiple target splits, perhaps even one per player.Different delivery types may yield different split times on the same shots.



Managing Different Split Times

Chances are your team will have different split times for different players.This is caused by different types of deliveries.It can be managed.The easiest way to manage the difference is to calibrate the team's weights based on long times (HTH) instead of split times.A long time of hog to hog will remain constant for all players, regardless of their delivery types.Split times are helpful but should be used as a sweeping tool and not an ice speed measurement.

Try this.When a player needs to know the speed of the ice, give them a long time then tell them what you're looking for as a split.

Example: (skip should know the Hog-to-Hog time and how the ice is running)

  • Skip in the hack
    "What are you guys looking for?"
  • Sweeper
    "We're looking for a 4.00 split"

Using both times is beneficial as the long time manages the ice speed throughout the game and the split time manages the skip's delivery.

Why are splits different for each player?
They're not always.Four players with similar deliveries will have similar split times.Different delivery types produce different split times.On a constant speed sheet, let's say 14.5 seconds, one player may have a split time of 3.80 and another may have a split of over 4.00.A hot split like the 3.75 is caused by a more decelerating delivery.This person may come out of the hack hard, decelerate, then deliver.They may have some extra drag from the back foot, a trailing knee, a slow slider, etc.On the other hand, a slow split like the 4.05 in this case, is the result of a delivery with less drag or a delivery that comes out of the hack soft (because they don't decelerate as much and perhaps pushed (add) at the end.

The goal is to have similar splits.If not, teams need extra time to learn the subtle differences in each player's deliveries.

Takeout Timing
All takeouts should be timed as well.The skip may time the takeouts HTH for future use.Remember, HTH does not have a useful in the moment component until the rock touches the playing end hog line.Split times can also be used on takeouts.Teams may have a standard takeout weight called normal takeout.When a skip calls for normal weight on the takeout, he or she expects normal weight.If the actual shot is higher or lower than normal weight, the sweepers must communicate the actual weight to the skip.First, decide on what you want for normal weight.This could change from team to team.

The split-times change based more on the desired weight of shot and not on the ice conditions. Your team may have several takeouts weights like hack, bumper, normal, peel and peel +.The following is rough example of split times a sweeper will look for on the takeouts.

Weight Split Target
Hack 3.40
Control 3.15
Normal 3.00
Peel 2.75
Peel + 2.50 or lower



Managing Different Split Times

Split to HTH Conversion
If your team uses HTH times as the communication base on takeouts (sweepers call out a 10.5 at release), a conversion is necessary.The sweepers don't actually know that the shot is a 10.5 since the HTH time is not complete.If they are split timing the takeout, they know that the split that they just took is a 3.0 split which would roughly convert to a 10.5 HTH.The designated HTH timer will be able to verify the call once the actual HTH is complete.

A word of caution on all split times.Don't rely on the clock as your sole judge of sweeping.As you develop, you will be able to judge rocks without the use of clocks.Great teams use a combination of judgment and clock speeds.

Timing System Suggestion:
Appoint one sweeper as the split timer and the other as the weight judger based on perception alone.As the timer, don't tell the other sweeper the slit time.Let the two methods work together.

In three or four seconds, you can get a pretty good sense of the weight.

Pro Tip:
In league play, never throw the first rock.Always split time a rock on an adjacent sheet to gauge draw weight.For example, you time the next sheet's first rock at 3.75 and watch where it stops.If it stops well short you and your sweepers will know to look for 3.65 (or so) on your first shot.Obviously, if it blows through the house, you can look for something like a 3.90.You can do the same with HTH times, but it takes longer.



Dialing-In the Shot

Some curlers use the ice timing information to calibrate shots.This is the next level of information use.Be careful not to over think the shot.For example:

The ice is running 14.5 HTH (and stopping on the tee, 50% swept)

  1. The skip calls a close guard (3 position)
  2. The sweepers say the ice is still running 14.5
  3. The thrower may say I'll throw a 14.8

This is example of the thrower dialing in the shot at 14.8.Consider making a seven-foot adjustment in the tee weight.Remember, there are an infinite number of weigh positions on an infinite number of tracks.Dialing in the shot is more useful as a short time since the sweeper can get immediate feedback. Dialing in HTH times cannot be confirmed until the far hog line.They are much less useful in this case.

The Future of Timing
Where are we going with timing rocks?Lots of changes in timing have happened over the last thirty years.Many players see timing is a mandatory key piece of science that can help the team.Since there is a human component to the science (someone still has to start and stop the watch), the practice will never be perfect.

Consider this...
Some top-level world teams are throwing away their stopwatches.Some people think that judging weight on draws is more of an art and are doing it by feel instead of science.It is still useful to measure and monitor conditions with times.