Understanding rankings

What is an Elo rating?

The BDA uses an Elo-based ranking system to estimate the strength of every crew.

Originally developed for chess, Elo works well for sport because it constantly updates based on who beats who and by how much.

The basic idea is simple:

• Beat stronger crews → gain more points
• Beat weaker crews → gain fewer points
• Lose to weaker crews → lose more points
• Lose to stronger crews → lose fewer points

Your rating is not a league position or a medal count. It is an estimate of your crew’s current competitive strength based on recent race results.

This rating sets an expectation of your performance at future events, and the system reacts when your result is better or worse than that expectation.

What is MultiElo?

Traditional Elo systems work best for one-on-one competitions. That obviously does not reflect a dragon boat race day.

MultiElo is an extension of Elo designed for races with multiple competitors. Instead of treating a race as winner versus loser, the system compares every crew against every other crew in the race.

For example, if 8 crews race:

• 1st place is treated as beating 7 crews
• 2nd place beats 6 crews and loses to 1
• 3rd place beats 5 crews and loses to 2
• And so on

The system then looks at:

1. What the expected finishing order should have been
2. What actually happened
3. How surprising the result was
4. The number of crews at the event

The more surprising the result, the bigger the rating change. The system expects higher-ranked crews to beat lower-ranked crews.

What data is added to the system?

After each race event, every entered crew is given a finishing position for each race. Those finishing positions are used to calculate a composite position.

For example:

• Crew A races in three distances and comes 1st, 3rd and 4th. Their composite finish position is (1 + 3 + 4) / 3 = 2.66.
• Crew B races in three distances and comes 2nd, 1st and 1st. Their composite finish position is (2 + 1 + 1) / 3 = 1.33.

Crews are then ranked by this composite number:

1. Crew B — 1st, with a composite position of 1.33
2. Crew A — 2nd, with a composite position of 2.66

How Elo ratings change

Winning crews take rating from crews they beat. Losing crews give up rating to crews that beat them, based on race position.

If a highly rated crew beats lower-rated crews, that was expected. The system effectively says: “you performed roughly as predicted.” The rating movement is therefore small.

But if a lower-ranked crew suddenly beats several strong crews, the system reacts strongly because the result was unexpected.

The ranking system also adjusts its expectations based on the number of crews at an event. The more crews in attendance, the more ratings can swing.

Beating strong crews is worth far more than beating weak crews, especially at larger events.

This means:

• A win against a few lower-ranked crews may mean little
• A strong performance at a race with lots of strong crews can massively affect rankings

How do composite crews get points?

Not to be confused with the composite position. A composite crew is a squad made up of more than one team. For a team to count as a composite it needs to have 4 or more members of another squad.

Composite crews act as a stand-alone crew with an ELO rank made up of its parent crews and based on the number of paddlers from each crew.

Ranking points lost and won by that crew are then distributed back to their parent crews - again based on the number of paddlers from each crew.

Example 1

Composite Dragons - a new crew consisting of 16 paddlers from Team A (1016 ELO) and 4 paddlers from Team B (1059 ELO)

• Start with an ELO based on their parent crew ELO ((1016/20)*16)+((1059/20)*4) = 1024.6
• Composite Dragons gain an ELO increase of 24 points after performing strongly on the day
• Crew A would gain ((24/20)*16) points or 19.2
• Crew B would gain ((24/20)*4) points or 4.8

Attendance is also worked out the same way so Crew A gains 0.8 attendance and Crew B gains 0.2

Example 2

Combined Dragons - a new crew consisting of 10 paddlers from Team A (900 ELO) and 10 paddlers from Team B (1100 ELO)

• Start with an ELO based on their parent crew ELO ((900/20)*10)+((1100/20)*10) = 1000
• Composite Dragons face a really strong field and lose 28 ELO points to other crews
• Crew A would lose ((28/20)*10) points or 14
• Crew B would lose ((28/20)*10) points or 14

Crew A gains 0.5 attendance and Crew B gains 0.5 attendance

How do I choose which race to attend?

If your crew has a low rank but is expected to perform strongly at a particular event, racing strong crews is beneficial.

Even mid-pack finishes can gain rating if expectations were low.

For example, if your crew is ranked low in the league and finishes above several crews ranked higher, your crew’s rating can rise significantly even without winning individual events.

This is one of the fastest ways to climb.

Should a strong crew attend a race if they expect to underperform?

This is one of the most interesting strategic questions in an Elo system. The honest answer is that it depends on what the crew values more: ranking protection or long-term competitive development.

What the rating system sees

The ranking system does not know:

• Who is missing
• Who is injured
• Whether half the crew could not travel
• If your strongest paddlers are unavailable

It only sees:

• The crew entered
• Who they raced
• Where they finished

If a top-ranked crew arrives weakened and finishes below expectation, the system will treat that as genuine underperformance, and that can lead to rating losses.

What can I use as a rule of thumb?