D1'45": what is a send-off on the clock?

You look at your programme, you read "8×100m freestyle, D1'45"", and you wonder what it means. What is that D? Why not just say "rest 15 seconds"? The answer changes how you train, and it brings you closer to how swimmers actually train.

D1'45": leave every 1 minute 45 seconds

D1'45" means you leave, or leave again, every 1 minute and 45 seconds. That is a send-off, more precisely a send-off on the pace clock.

In practice, if you swim 100m in 1'30", you have 15 seconds of rest before you go again. If you swim it in 1'38", you only have 7 seconds. If one day you swim it in 1'50", you wait for the next send-off.

Why this, rather than a fixed rest?

Because it rewards the swim. The faster you go, the more you recover. The better you work, the more comfortable the interval becomes. It is a progress tool built into the session, and it also gives you an objective read on how you are that day.

The pace clock: your best friend

Every pool has a big round clock with a red hand (sometimes green) that turns. It completes one full revolution in 60 seconds. It is the reference tool of any swimmer who trains seriously.

How to use it:

You do not have to leave at one exact moment on the dial. Look at where the hand is when you leave, and leave again when it comes back to that same spot, or after 1'45" if the send-off is 1'45".

Example: you leave when the hand is on the 12. You come back to the wall. You leave again when it is back on the 12 (one full turn = 1 min), or on the 9 if you are waiting 1'45", or on the 6 for 1'30".

What an experienced swimmer does: they never look at a watch during the sets. They glance at the clock as they hit the wall, see where the hand is, and know straight away whether they are on time.

The watch: useful, but not for the rests

A lot of beginners make the same mistake: they use the watch to run their rests. They hit "lap" on every wall, look at the time, wait 15 seconds, and leave. It works, but it breaks the rhythm, and it pulls you out of the pool.

The right way to use the watch:

Start it on the first send-off of the set. Stop it after the last repeat. That is all.

The watch is useful for 3 things: - Strava: keep a clean history of your kilometres, and see your progress over time - Your average: even if the pauses between sets skew it a little, it is a fair picture of your overall pace - Where you are in the distance: "I have swum 1800m, I have 400m left". The watch keeps that count for you

During the sets, let the pace clock do the job. It sets the tempo. The watch is for afterwards.

Why swimmers trust the hand

In a club, nobody checks a watch during the sets. Everyone keeps an eye on the pace clock. Why?

Because it is more precise, smoother, and it teaches you more. The clock does not lie. If you reach the wall and the hand has already gone past your mark, you have a question to ask about your pace. If you have 20 seconds in hand, you know you went too fast on that repeat.

Over time you build an internal sense of pace. You know, within about 5 seconds, what a 100m will take. That is swimming with your head as well as your arms.

How the skill develops:

1. At the start: look at the clock on every finish and count the seconds 2. After a few sessions: estimate the time before you even reach the wall 3. Later: feel whether you are on time from the first turn

It is not a gift. It is what happens when you look at the clock, every set, for a few months.

A practical summary for your next session

Before you get in: Find the pace clock. Note where the red hand is.

On the first repeat: Start your watch. Leave when you are ready.

On every wall: Look at the hand. Remember its position. Leave again when it comes back to the same point, or to the point that matches your interval.

At the end of the set: Stop the watch. Note the total time if you want to. Rest between sets however you like.

Keep this: - D1'45" = you leave again every 1'45" (your swim time + your rest) - The pace clock = your reference timer during the sets - The watch = your tool for Strava, the distance, and your overall average - The faster you swim, the more you recover. That is the point of a send-off