Pace clocks

From Libre Aquatics Wiki, the free aquatics reference

A pace clock, or interval clock, is a large display that counts seconds and minutes beside a training pool so that swimmers can read their own send-off times and rest intervals without a coach calling every one. It shows elapsed time rather than a race result, so it sits outside the competition timing chain that a timing console and a scoreboard form, even when the same board does both jobs on different days.

How a pace clock is used¶

Interval training divides a session into sets of repeats with a fixed departure time. A set written as 10 × 100 on 1:30 means ten repeats over 100 metres or yards, each swimmer leaving the wall every minute and a half, with whatever time is left after the swim serving as the rest. The clock makes that self-directed: swimmers watch the sweep or the digits and go on their own interval, and a lane can run a different set from the lane beside it.

Two conventions follow from that. A clock may count up, so the reading is the elapsed time of the current repeat, or count down to zero at the moment of departure. Where several swimmers share a lane they leave in sequence rather than together, spaced by a few seconds, which is why clocks and the equipment that drives them provide a horn or tone that can sound a series of send-offs rather than a single start.

Ways of driving a pace clock¶

Four arrangements appear in the Colorado Time Systems documentation, and they differ in where the workout is stored.

A standalone clock keeps its own settings and is programmed from buttons on the unit. This is the ordinary case for the current pace clocks, which CTS sells with 10 in LED digits in red or amber, and for the slim clocks with 2.4 GHz wireless built in.¹

A workout controller stores the session and plays it out to one or more displays over a data cable. The pace clock controller is the long-running example, holding fifty workouts and addressing up to ten displays, so every line of a multi-line board can run a different set at once.² The handheld segment timer is the later wireless equivalent, with a smaller capacity, reaching portable scoreboards, deck clocks and the slim pace clocks over a 2.4 GHz link.³

A timing console can do the same job from a program sold separately: the System 6 and System 5 each have a pace clock program with its own guide, which turns the competition console into the training-side source.⁴⁵

Finally, a display need not be a pace clock at all. A numeric scoreboard that accepts the same data will show a workout, which is how a facility avoids buying a second set of hardware for training.²

Pace clocks and shot clocks¶

Most CTS clock enclosures are sold to do both jobs, and the user guides are titled for the pair: basic, pro, wireless portable and standard, and wireless pro each cover a pace clock and a shot clock in one document.⁶⁷⁸⁹ The difference is the role rather than the hardware. A shot clock counts a possession in water polo and is part of the game, governed by the rules of that sport, while a pace clock counts a training interval. This section covers the training role and the water polo section covers the other.

One governing body does specify pace clocks, and it does so for warm-up rather than for racing. USA Swimming rule 103.20 sets a floor of two clocks wherever swimmers warm up or warm down, asks that they be large and accurate, and wants every swimmer in the area able to see one. Splitting them between the two sides of the course is a stated preference rather than a requirement.¹⁰ Note how little the rule pins down: no accuracy figure, no digit size, no display format, and it is an LSC-level provision rather than a national technical rule. The World Aquatics, NCAA and NFHS documents held for this wiki do not mention pace clocks at all, which fits the division of roles above: no result in a competition depends on a pace clock.

Products¶

This section catalogs the pace clock hardware named in the articles on this wiki. The pace clock controller and the handheld segment timer have had research passes of their own; the rest are stubs, written from what a manual says in passing.

Product	Maker	Type	Status
Pace clock controller	Colorado Time Systems	Keypad console storing and playing out workouts	Listed as current¹
Ultimate Pace Clock	Colorado Time Systems	The system the controller was sold as part of, with two portable displays¹¹	No longer listed
Handheld segment timer	Colorado Time Systems	Wireless handheld interval controller, `WHC-2`	Current¹²
Slim pace clock	Colorado Time Systems	Wall-mounted LED clock, four or six digits, `MS-0037`–`MS-0040`	Current
Deck clock	Colorado Time Systems	Portable game, shot and pace clock, `MS-0043`–`MS-0045`	Current
SASC9	Colorado Time Systems	Named as a display the controller drives; nothing further established	Unestablished

The multisport portable scoreboard is the third display a segment timer drives, and is filed with the scoreboards. CTS’s clock line beyond all of these, still uncovered, is the pace clocks for training.¹ The counting clock pro is uncovered too, but it is not on that page; it is attested only by its own user guide, F925.¹³

References¶

Colorado Time Systems, Pace Clocks and Shot Clocks (current line, as of 2026). ↩ ↩² ↩³
Colorado Time Systems, System 6 Pace Clock Software User Guide (F873). ↩
Colorado Time Systems, Pace Clock for the System 5 Sports Timer Software User Guide (F509 Rev. 0698). ↩
Colorado Time Systems, Basic Pace Clock and Shot Clock User Guide (F890 Rev. 202008). ↩
Colorado Time Systems, Pro Pace Clock and Shot Clock User Guide (F891 Rev. 202008). ↩
Colorado Time Systems, Wireless Pro Pace Clock and Shot Clock User Guide (F904 Rev. 202507). ↩
Colorado Time Systems, Wireless Portable and Standard Pace Clock and Shot Clock User Guide (F910 Rev. 202008). ↩
USA Swimming, Rulebook, 103.20 Pace Clocks (warm-up and warm-down areas). ↩
Colorado Time Systems, Wireless Handheld Segment Timer (current listing, as of 2026). ↩
Colorado Time Systems, Counting Clock Pro User Guide (F925). ↩

Last updated September 25, 2026.