Watt and Split Lookup for Aussie Sheds
Coach hands you a watt target on the whiteboard. The PM5 is showing a split. This tool turns one into the other in a single tap, off the published Concept2 cubic equation, so the watt-pegged interval sheet the coach drew up at Penrith reads as the exact split your ergo monitor will hold during the piece.
Turning a watt figure into a 500m split on a Concept2 ergo
Concept2 ties pace to power through one published cubic equation: watts = 2.80 divided by the cube of (split-seconds divided by 500). Rearrange it the other way and split equals 500 multiplied by the cube root of (2.80 divided by watts). A round 200W lands on 2:00.5, 250W on 1:51.9, 300W on 1:45.3, and 400W on 1:35.7. The cube on the denominator is what hurts. Moving from 2:00 to 1:50 needs about 61 extra watts. Moving from 1:50 to 1:40 needs another 87.
Inputs
Indicative bands: masters social 100-200W; trained open club 250-350W; King's Cup shortlist and AIS scholars routinely above 400W.
Aussie squad sessions usually fall between 1:30 (national-grade) and 2:30 (first ergo of the schools season).
At that effort
- kcal per hour:
- Olympic 2k pace:
- 5k aerobic pace:
Watt and split lookup table
Common watt and split pairs straight off the Concept2 cubic equation. Pin this above the shed ergo for watt-pegged interval blocks and the wattage targets the coach writes up before a Penrith camp.
| Split per 500 | Watts | Olympic 2k | kcal per hour |
|---|---|---|---|
Method behind the lookup
The Concept2 cubic equation that ties watts to split
The same equation sits inside every Concept2 PM3, PM4 and PM5 in the country: watts = 2.80 / (split_in_seconds / 500)^3. Flip it the other way and you have split = 500 * (2.80 / watts)^(1/3). Both directions are clean arithmetic, no regression, no fudge factor. The watt reading on a Concept2 ergometer falls straight out of the cubic equation against measured flywheel deceleration. To plug a 500m split into a fuller workup with kilojoules and projected finishing times across every test distance, jump to the ergometer pace tool.
Why twice the watts is not half the split
Pace and power scale as a cube. Double the watts and the split number drops by about 21 percent, not 50. Moving from 1:40 to 1:30 needs about 130 extra watts. Moving from 1:50 to 1:40 needs about 87. Coaches should check the matching split before setting watt targets for a session.
When this lookup actually earns its keep
Three regular use cases in an Aussie shed. One, a coach prescribes a watt figure for a Tuesday interval block and the rower needs the split to hold on the PM5 mid-piece. Two, the squad runs watt-pegged intervals across mixed athletes (a 65kg cox-trainee and a 95kg M8+ stroke holding the same watt target on different splits) and the session sheet logged inside the squad session record needs both columns. Three, max-power efforts (10-stroke bursts, one-minute power tests, peak-watt jumps on a Wattbike-style ergo trial) where the watt figure is the honest unit and the split is the read-out. For zone splits, stroke rates and interval breakdowns off a 2k score, the training pace calculator is the next stop.
One conversion is arithmetic. A whole shed of watt logs is a database job.
Turning one number into another is a five-second job on this page. Tracking the watt progression of 40 athletes across a Penrith winter, a pre-Yarra block and a build to the Australian Schools Championships is the bit a spreadsheet starts losing data on. Row HQ writes every ergo piece against the right athlete the moment it lands, so the coach pulls crew selection lineups off live watt and split data, picks up a sculler plateauing through the admin dashboard, and stops trawling the squad WhatsApp for a PB. The OTRC case study walks through how a real club uses ergo numbers day to day, and the side-by-side against the shared spreadsheet most boatsheds are still running tells the rest of the story.
Frequently asked questions
How tight is the Concept2 watt figure against the published equation?
Yes. Concept2 publishes the equation and every PM3, PM4 and PM5 monitor uses it. The watt number on the screen comes from how fast the flywheel slows between drives. Drag factor shifts the air load per stroke and the rate you settle into, but it does not change the watt-to-split relationship. A 250W hold reads as 1:51.9 at drag 110 or drag 140.
Why does doubling the watt figure not halve the split number?
Because pace and power are tied through a cube on the denominator. Halve the split number and watts multiplies by eight. Run the other direction and doubling the watts only pulls the split number down by about 21 percent. That is the reason the climb from 1:40 toward 1:30 takes a wildly different effort than 2:00 toward 1:50. The bottom of the curve is exponentially more expensive in watts, and no Penrith camp gets you there without sustained aerobic base behind it.
What watt figure puts you under 7 minutes for the Olympic 2k?
A 7:00 ergo means holding 1:45 per 500, which needs about 302 watts. Going under seven minutes needs more than 302 watts on average. A 6:30 needs about 378 watts, while a 6:00 needs about 480. Body weight and drag factor do not change this conversion.
Does shifting drag factor change the watt-to-split lookup?
No. The cubic equation uses the same 2.80 coefficient at every drag setting. Drag factor changes how the catch loads and what rate feels natural, but a 250 watt average reads as a 1:51.9 split at any drag setting. Pick drag for the athlete's build and stroke, not to chase a faster number.
Why does the watt reading on the PM5 jump around during a steady piece?
Watts is calculated stroke by stroke off flywheel deceleration. Any small wobble in drive force shows up as a watt swing even when the split-by-stroke reads rock steady. Most Aussie crews end up pacing steady-state pieces off the split number (it averages cleaner across the drive) and switch over to the watt number for max-power testing where stroke-to-stroke output is the bit that matters. Both numbers are honest, they just smooth differently.
How does the kcal per hour figure on the C2 screen tie back to watts?
Concept2 estimates it with kcal per hour = (watts x 4) + 300. The standing 300 represents resting metabolism during exercise. So 200W reads as roughly 1,100 kcal per hour and 300W as roughly 1,500. The real burn rate moves with body mass, muscle composition and shed temperature on the day, but the figure is repeatable enough across sessions to use as a relative training-load metric when planning fuelling through a King's Cup build block.
Companion tools in the Aussie ergometer suite
Ergometer Pace and Distance Tool
Drop a 500m split into the box and read watts, kJ, kcal and projected splits from a 500m flyer through to the marathon piece.
Drag Factor Calculator
Find a drag factor that fits the athlete's build, experience and the boat class on the water.
Stroke Rate Calculator
Work out distance per stroke off rate and split, or back-solve a target rating from a chosen pace.
Bodyweight-Adjusted Ergometer Score
Set lightweight and openweight 2k scores on a fair scale for selection night reads.
Tracking watt progression across a forty-athlete squad
Row HQ writes every ergo piece, split and watt figure against the right athlete the moment it lands, so coaches read power trends off a dashboard instead of trawling the squad WhatsApp for last fortnight's PB.