Heat planning is where most simulation days are won or lost. Get it right and athletes start on the minute, judges get breaks and the sled crew is never rushing a plate change. Get it wrong and you have three athletes queuing at one sled while the next heat is already running past them.
This guide covers the decisions in the order you make them, then works through a full example with numbers. It assumes a run-and-station format; the same logic applies to zone races and relays.
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The terms
A heat (the official race calls them waves) is a group that starts at the same time. A lane is one athlete’s, pair’s or team’s set of equipment for the whole race: rower 2, sled 2, wall-ball target 2 and so on. The start interval is the gap between consecutive heat starts.
The official race’s rulebook says it uses wave starts “at regular scheduled intervals”, giving every 10 minutes as an example, and assigns each racer a start time in advance. That is a useful model: fixed clock times, published early, are what let athletes plan warm-ups and let you run the day from a sheet rather than from memory.
Step 1: count lane units
Entries are not the same as lanes. Count:
| Entry type | Lane units | Notes |
|---|---|---|
| Single athlete | 1 | One athlete per lane |
| Doubles pair | 1 | Both partners share one set of equipment |
| Relay team of four | 1 | One member works at a time |
In the official race’s doubles format, both partners must run every run together and one partner works at a time on each station, which is why a pair needs only one lane. In its team relay, each of the four members runs two 1 km (0.62 mi) segments and does the two stations that follow. If you run a four-person team relay or a partner relay, plan the change-over area beside the lane so the next runner is not standing on the run route.
Your maximum lanes per heat is the number of complete station sets you have. If you have four rowers but two sleds, you have two lanes, unless you accept athletes waiting at the sled. Waiting time is the main reason sims run late.
Step 2: work out the heat count and last start
Two formulas do most of the work:
- Heats = lane units ÷ lanes per heat, rounded up.
- Last start = first start + (heats − 1) × interval.
Then add your time cap to the last start to find the latest possible finish. The time cap is your choice as organiser; pick one that lets nearly everyone finish and write it on the heat sheet.
Step 3: choose the interval
The interval has to be long enough for a heat to clear your scarcest single-equipment station before the next heat arrives at it. In most gyms that is the sled push or sled pull, because each athlete holds the sled for the whole station and you rarely have spares.
A practical way to set it: estimate how long your slowest likely athlete spends on the sled station, and make the interval at least that. If you have no data yet, run a short test with two members on your floor and sled. Then watch the first two heats on the day. If athletes are queuing at the sled, lengthen the interval for the remaining heats, recalculate the later start times and announce them before those athletes warm up.
How the interval changes the day for 16 heats:
| Interval | Last start after first | With a 75-minute cap, latest finish after first start |
|---|---|---|
| 6 minutes | 90 minutes | 165 minutes |
| 8 minutes | 120 minutes | 195 minutes |
| 10 minutes | 150 minutes | 225 minutes |
Seeding matters too. If faster athletes start after slower ones, they catch them on the course and queue at the sled. Starting the fastest heats first avoids that. If you want a showcase final heat, put one empty slot before it.
Step 4: minimise sled-weight changes
Every sled-load change takes plates off and on, mid-race, while athletes from the previous heat may still be pushing. There are two ways to cut the number of changes.
Block heats by load. Run every heat on the same load consecutively. Instead of changing weights up to 15 times across 16 mixed heats, you change them once per block boundary. Put one empty interval at each boundary so the sled crew can change plates on an empty station.
Lock loads to lanes. If your divisions are roughly balanced, give lanes 1 and 2 one load and lanes 3 and 4 another, and never change them. This works well with two loads and even numbers. It breaks down when one division is much bigger, because you end up with empty lanes in many heats.
SimDay builds heats by division, lane and sled weight, so each heat sheet shows which load every lane needs. Deciding where the blocks fall and where to insert the empty slot is your call as organiser. Set your own loads per division; the defaults in the tool are placeholders, and if you want to mirror a specific race, check its current rulebook.
Step 5: check people against the schedule
Coaches, judges and volunteers who also race are the biggest source of day-of chaos. For each person, check:
- They are not judging, coaching or on the sled crew while their own heat is running.
- There is a gap of at least the time cap plus a recovery and reset window between their race and their next duty. That window is your call; agree it with them in advance.
- Coaches are not racing at the same time as the athletes they want to watch or coach from the side.
The simplest pattern is to put staff in the first heat or the last heat. First-heat racers then judge for the rest of the day; last-heat racers judge the early heats and race once the floor quietens. Ask about conflicts on the entry form, not on the morning.
Worked example: 64 athletes, 4 lanes, 8-minute interval
A gym has 64 single entries across three divisions on different sled loads: 16 on a light load, 32 on a standard load and 16 on a heavy load. It has four complete lanes, sets an 8-minute interval and a 75-minute time cap, and wants the first heat to start at 09:00.
Heats. 64 ÷ 4 = 16 heats: 4 light, 8 standard, 4 heavy.
Load blocks. Heats 1–4 light, 5–12 standard, 13–16 heavy. That is two load changes instead of up to fifteen. Add one empty 8-minute slot at each change.
Start times.
| Block | Heats | Start times |
|---|---|---|
| Light load | 1–4 | 09:00, 09:08, 09:16, 09:24 |
| Empty slot (sled change) | none | 09:32 |
| Standard load | 5–12 | 09:40 to 10:36, every 8 minutes |
| Empty slot (sled change) | none | 10:44 |
| Heavy load | 13–16 | 10:52, 11:00, 11:08, 11:16 |
Without the empty slots the last heat would start at 11:00, which is 15 × 8 = 120 minutes after the first. With them it starts at 11:16. Add the 75-minute cap and the last athlete must be finished by 12:31. Build in briefing time before 09:00 and results and awards after the last finish, and you have a schedule you can publish.
What if half the field enters as doubles? If those 64 athletes were 32 doubles pairs, that is 32 lane units and 8 heats; the last start is 7 × 8 = 56 minutes after the first.
Publishing start times
Publish clock times, not heat numbers alone, and do it a few days before. Print the heat sheet for the start line and the judges, and show the next few heats on the TV board so athletes call themselves up. Lock the schedule once published; if you must move someone, tell their lane judge as well as the athlete, so the right name is on the judge’s phone in judge mode.
For the rest of the day’s plan, see how to run a HYROX-style simulation, then build your heats in SimDay, free during the beta.