How to score a race when the boats don't match

At a small club you race whatever shows up. I sail a Flying Scot, which is a nineteen foot boat with a crew. Next to me on the start line there might be a Sunfish with one person on it. The Scot is faster, so the first boat across the line tells you very little about who sailed best.

The yardstick

The Portsmouth yardstick fixes this with one number per type of boat. A slower boat gets a higher number. After the race you take each boat's time and correct it.

Corrected time is the elapsed time, multiplied by 100, divided by the boat's Portsmouth number.

The lowest corrected time wins.

A made-up example

Say a Flying Scot carries a number of about 90 and a Sunfish about 100.

The Scot finishes in 45 minutes. 45 times 100, divided by 90, is 50 minutes.
The Sunfish finishes in 49 minutes. 49 times 100, divided by 100, is 49 minutes.

The Sunfish crossed the line four minutes later and won by a minute. The number says a well-sailed Sunfish should take about eleven percent longer than a well-sailed Scot. This Sunfish took less than that, so it sailed the better race.

Score your own race

Put in each boat's Portsmouth number and elapsed time. The calculator starts with the example above.

For real scoring, use the current numbers from US Sailing's Portsmouth tables. The two here are round numbers for the example.

What it's like in practice

I scored one of our club races this way, with some help from Claude. I finished third on corrected time. I mention that only to show the math doesn't play favorites with whoever is running it.

What the number can't do

The yardstick assumes average conditions. In very light wind or a real blow, some boats do better than their number says. There are wind-adjusted versions of the numbers for that. For a weeknight club race, the plain number is close enough and nobody has to argue past dinner.

Why I like it

It means anyone can race. You don't need the same boat as everyone else. You need a boat, a start line and somebody willing to do a little division afterward.