Time-on-Distance —Arriving at the Start at Exactly the Right Moment
PMR Sailing | Learning to Race — From First Start to Better Results | Part 4
The perfect start begins before the starting gun.
One boat is already sitting almost on the starting line. Surely that is the perfect position?
Another boat is 30 metres behind, apparently rather late. Yet as the final seconds tick away, the second boat accelerates, sails straight through a gap and crosses the line at speed just as the starting signal sounds.
Within a few seconds, it has sailed clear of the boat that was waiting on the line.
How did that happen?
The answer is one of the most useful skills in racing: time-on-distance.
It sounds technical, but the principle is remarkably simple. You need to know how far you are from the starting line, how quickly your boat can cover that distance, and when to begin your final approach.
Getting all three right can transform your starts.
1. Why Being on the Starting Line Is Not Necessarily a Good Start
When learning to race, it is tempting to think that the objective is simply to be as close as possible to the starting line when the starting signal sounds.
That is only part of the story.
A good start usually combines three things:
Crossing the line at, or very shortly after, the starting signal.
Travelling at a useful speed, ideally close to your best speed for the conditions and sailing angle.
Having clear wind and enough room to sail the course you want.
A boat that is stationary on the line may have achieved the first objective, but it can be badly disadvantaged on the other two.
Consider two boats.
Boat A has been sitting almost stationary just behind the line for the final 15 seconds. Its sails are flapping, the rudder is moving from side to side, and the crew is desperately trying to prevent the boat drifting over early.
When the starting signal sounds, the helm sheets in and tries to accelerate.
Boat B has approached from behind with its sails drawing. It reaches the line at the starting signal already travelling at a useful speed.
Within seconds, Boat B is moving ahead.
Boat A may have been closer to the line throughout the countdown, but Boat B has made the better start.
There is an important qualification: skilled sailors sometimes deliberately hold a boat close to the line to protect a gap, then accelerate at exactly the right moment. The problem is not being close to the line; it is being close without enough speed, space or time to accelerate.
2. Understanding Time-on-Distance
The basic calculation is straightforward:
Time = Distance / Speed
If you know how far you are from the line and your speed towards it, you can estimate when you will arrive.
For example, imagine you are 40 metres from the starting line, travelling directly towards it at 4 knots.
One knot is approximately 0.514 metres per second.
Therefore:
Speed = 4 x 0.514 = 2.06 metres per second
Time = 40 / 2.06 = 19.4 seconds
You will reach the line in approximately 19 seconds if your speed remains constant.
If there are 20 seconds remaining before the start, your timing is almost perfect.
However, real sailing is rarely that straightforward.
Your speed changes as the wind increases or decreases. You may need to bear away, head up, avoid another boat or wait for a gap to appear.
And, most importantly, a boat that starts from almost stationary will take time to accelerate.
The calculation also needs to use your speed towards the line, not simply the speed shown by a GPS.
3. How Far Can You Travel in Ten Seconds?
A useful skill is developing an instinctive understanding of how far your boat travels in a short period.
The following table assumes steady speed and movement directly towards the line.
Boat speed | Distance in 10 seconds | Distance in 20 seconds |
|---|---|---|
2 knots | 10.3 m | 20.6 m |
3 knots | 15.4 m | 30.9 m |
4 knots | 20.6 m | 41.2 m |
5 knots | 25.7 m | 51.4 m |
6 knots | 30.9 m | 61.7 m |
8 knots | 41.2 m | 82.3 m |
These figures reveal something interesting.
At 5 knots, a boat can travel more than 25 metres in just ten seconds.
At 8 knots, it can travel more than 40 metres.
That means a fast boat can be surprisingly far from the starting line with only a few seconds remaining and still make a perfectly timed start.
Equally, if you misjudge the timing by five seconds, you could be many metres early or late.
This becomes particularly relevant when moving between different types of boat.
A sailor accustomed to a relatively modest dinghy may find that the same approach simply does not work in a faster racing boat.
4. Acceleration — The Missing Part of the Calculation
The time-on-distance formula assumes that the boat is travelling at a constant speed.
But what happens when the boat is almost stationary?
Imagine a dinghy waiting near the line with its sails eased.
When the helm sheets in, it does not immediately reach 4 knots.
It takes time to accelerate.
During those first few seconds, the boat travels a much shorter distance than it would at full speed.
For a simple illustration, suppose a boat accelerates uniformly from rest to 4 knots over ten seconds.
Its average speed during that period would be approximately 2 knots.
Therefore, it would travel only about 10 metres during those ten seconds, rather than the 20.6 metres it would cover at a steady 4 knots.
Real acceleration is not uniform, but the example demonstrates the principle.
The time needed to reach the line depends on both your present speed and how quickly your boat accelerates.
This is why sailors who understand their own boats can have such a significant advantage.
They are not simply guessing how far away the line is. They have learned how their boat responds when they sheet in, bear away and build speed.
5. Why Champagne Makes This Particularly Interesting
Sailing Champagne, our Thames A-Rater at Upper Thames Sailing Club, introduces another dimension to the problem.
An A-Rater is not simply a conventional dinghy with a larger sail.
Its long, lightweight hull, very tall rig and substantial sail area create a different sailing experience.
Once moving efficiently, an A-Rater can achieve impressive speed. But getting the boat moving, keeping the sails drawing correctly and maintaining balance requires coordination between the helm and crew.
The precise acceleration characteristics depend on the wind, the crew, the sail settings and the boat's condition. They are something we need to measure and learn rather than assume.
Consider two hypothetical approaches to a start aboard Champagne.
Approach A: The stationary start
We position ourselves close to the line with 20 seconds remaining.
To avoid crossing early, we slow the boat almost to a standstill.
The sails lose some of their driving force. The crew then has to coordinate the acceleration as the starting signal approaches.
If the boat takes longer than expected to build speed, we cross the line slowly and may immediately find ourselves in disturbed air.
Approach B: The moving start
We position ourselves further back and establish a controlled approach.
The helm has room to steer, the sails are drawing and the crew knows when the final acceleration should begin.
As the final seconds disappear, we build speed and cross the line moving efficiently.
Even if the two approaches cross at almost the same moment, the second may give us a much better first 30 seconds of racing.
And those first 30 seconds can determine whether we sail in clear air or spend the opening leg trying to escape from other boats.
There is also an important difference between an A-Rater and a smaller dinghy: its size and momentum make last-second corrections more consequential. You cannot necessarily stop, turn or accelerate in exactly the same way.
That makes advance planning particularly valuable.
6. A Practical Example — Twenty Seconds to Go
Let us imagine a club race with 20 seconds remaining.
Our boat is 35 metres from the starting line, making approximately 4 knots towards it.
Using the earlier calculation:
Time = 35 / 2.06 = 17 seconds
At the present speed, we would cross the line three seconds early.
That may not sound significant, but three seconds at 4 knots represents more than six metres.
We therefore need to adjust our approach.
Possible choices include easing the sails slightly, sailing a less direct course or briefly reducing speed before accelerating again.
But each adjustment has consequences.
Easing the sails too much may destroy our speed.
Changing direction may take us into another boat's path.
Slowing too early may leave us struggling to accelerate.
The best choice depends on the available space, other boats and the wind.
This is why time-on-distance is not simply a mathematical exercise.
It is a practical judgement made in a constantly changing environment.
Try a time-on-distance calculation
Assume steady speed directly towards the line, with no current.
Distance to line
40 m
Speed towards line
4 knots
Time remaining
20 seconds
Estimated arrival
19.4 s
Starting difference
0.6 s
Early
At this speed, you would reach the line before the starting signal.
For illustration only. Real starts require allowances for acceleration, current, wind shifts and other boats.7. The River Adds Another Complication — Current
At Upper Thames, we are racing on a river rather than an open stretch of water.
That makes time-on-distance more interesting.
The current can change how quickly a boat moves towards the line relative to the riverbank.
Imagine a boat sailing at 4 knots through the water towards a starting line, with a current of 1 knot flowing in the same direction.
Its speed over the ground is approximately 5 knots.
If the current is flowing against the boat, its speed over the ground is approximately 3 knots.
The difference is substantial.
For a 30-metre approach:
Conditions | Speed over ground | Time to line |
|---|---|---|
No current | 4 knots | 14.6 s |
1-knot following current | 5 knots | 11.7 s |
1-knot opposing current | 3 knots | 19.4 s |
These are illustrative figures rather than typical current speeds at Bourne End. They assume that the boat, current and approach are aligned.
A following current could push you across the line earlier than expected, particularly if you are trying to hold position close to it.
An opposing current could make you late despite the boat feeling as though it is moving quite quickly through the water.
There is another subtle point.
A boat's speed through the water and its speed over the ground are not necessarily the same.
A GPS normally reports speed over the ground, while the feel of the boat, sail forces and many traditional speed instruments relate more closely to its movement through the water.
For starting calculations, what matters is how quickly you are closing the distance to the fixed starting line.
8. The Angle of Approach Matters Too
Suppose your boat is travelling at 4 knots, but instead of sailing directly towards the line, you are approaching it at an angle.
Only part of your speed is taking you closer to the line.
For a straight starting line and a steady course:
Speed towards line = Boat speed x cos(angle from the perpendicular to the line)
For example, at 4 knots and 60 degrees from the perpendicular:
Speed towards line = 4 x 0.5 = 2 knots
You may be travelling at 4 knots, but you are closing the distance to the line at only 2 knots.
This explains why two boats travelling at similar speeds can reach the starting line at very different times.
One may be sailing almost directly towards it while the other is travelling largely along it.
The latter may be maintaining useful boat speed without using up much of its remaining distance.
That can be a useful technique when positioning for a start, provided there is sufficient room and the manoeuvre is consistent with the racing rules.
9. The Final Minute — A Practical Starting Routine
It is helpful to develop a consistent routine rather than improvising every start.
60 seconds remaining — Establish your position
Identify the line, check the wind, consider the current and decide where you want to start. Look for other boats likely to restrict your approach.
30 seconds remaining — Set up your approach
Estimate your distance, speed and likely acceleration time. Make sure there is a usable route to the line and that your crew understands the plan.
15 seconds remaining — Build and control speed
Make small adjustments. Avoid unnecessary manoeuvres that destroy momentum. Look for the space you will need immediately after the start.
5 seconds remaining — Commit to the start
Aim to be accelerating or already moving efficiently. Check that you will not cross early, and be ready for nearby boats to change course.
Starting signal — Sail away cleanly
Cross the line legally, maintain speed, find clear air and concentrate on the first leg.
This is a guide rather than a rigid countdown. Different boats and conditions require different timing, and the starting signals are governed by the sailing instructions and applicable racing rules.
10. What Happens When You Get It Wrong?
Even experienced sailors occasionally misjudge a start.
There are two particularly common mistakes.
Arriving too early
You have ten seconds remaining and are already almost on the line.
Your options may be limited.
You can slow down, but that risks losing momentum. You may try to bear away or sail along the line, but other boats may restrict your movement.
Crossing early can result in a recall and the need to return and start correctly under the applicable starting rules. In some races, a special starting penalty may apply.
Prevention is much better than trying to recover.
Arriving too late
The starting signal sounds, and you are still 20 metres behind the line.
It is tempting to panic, sheet in hard and point directly towards the first mark.
But oversheeting or heading too high may slow the boat even further.
Often the best recovery is to establish speed, cross the line cleanly and sail in clear air rather than making a rushed manoeuvre.
A slightly late start with speed can be better than a badly executed attempt to recover those lost seconds.
And remember: one poor start does not mean the race is over.
11. Three People, One Start — Crew Coordination on Champagne
An A-Rater such as Champagne makes teamwork particularly important.
With three people aboard, the starting approach needs clear communication.
One possible arrangement is:
The helm: Concentrates on steering, maintaining boat speed, avoiding other boats and choosing the final approach.
The mainsail trimmer: Concentrates on sail power, responding to the helm's instructions and helping the boat accelerate without losing balance.
The forward crew: Helps with the headsail, observes traffic and, when appropriate, provides distance and timing information.
The precise responsibilities will vary with the crew and conditions.
What matters is that everyone knows who is doing what.
There is little benefit in three people simultaneously shouting different estimates of the distance to the line.
A simple countdown can be far more useful.
For example:
"Twenty seconds. Thirty metres."
"Fifteen seconds. Good speed."
"Ten seconds. Keep building."
"Five, four, three, two, one — start."
Of course, those calls are only useful if they are reasonably accurate.
Developing that accuracy is something we can practise.
12. A Training Exercise — Discover Your Boat's Acceleration
One of the best ways to improve starting performance is to carry out a controlled experiment.
This is particularly worthwhile when learning a new boat.
Choose a quiet area of water, clear of other traffic, with suitable conditions.
Set up a simple timed exercise.
Begin with the boat moving slowly on a chosen course.
At a signal, trim the sails and accelerate.
Record the time taken to reach a useful sailing speed.
Repeat the exercise several times.
Compare the results in different wind strengths.
If you have a GPS or suitable sailing instrument, record the speed over ground at regular intervals.
You could produce a table like this:
Time after acceleration | Illustrative speed |
|---|---|
0 seconds | 0.5 knots |
5 seconds | 1.8 knots |
10 seconds | 3.2 knots |
15 seconds | 4.1 knots |
20 seconds | 4.6 knots |
Example of speed building during the first 20 seconds.
The results can help you understand how long you need to accelerate before reaching the line.
With repeated practice, you begin to recognise the right moment without constantly looking at instruments.
For Champagne, I would be particularly interested in comparing starts from near-stationary conditions with starts made while maintaining moderate boat speed.
The difference could be quite revealing.
13. A Second Exercise — The Invisible Starting Line
This is a useful training activity for a sailing club.
Choose two suitable fixed reference points or laid marks to represent a starting line, in an area where it is safe to practise.
Set a countdown timer for 60 seconds.
The objective is to cross the imaginary line at full useful sailing speed as close as possible to zero.
Repeat the exercise, but change the starting distance.
For example:
First attempt: 50 metres behind the line.
Second attempt: 30 metres behind the line.
Third attempt: 20 metres behind the line.
Record whether each attempt was early or late and estimate the crossing speed.
The exercise becomes more interesting if the crew must estimate the distance without relying on a GPS.
They will quickly discover that estimating distance from a moving boat is not as easy as it appears.
For new racers, I would initially run the exercise with one boat at a time. Once everyone is confident, several boats can practise together under suitable supervision, with adequate separation and clear instructions.
That introduces the tactical complications of a real start.
14. Time-on-Distance Is Only Half the Battle
There is a danger in becoming too focused on crossing the line at precisely the right second.
You could make a mathematically perfect start in completely the wrong place.
Imagine crossing at the starting signal, travelling at excellent speed, but directly behind another boat whose sails are disturbing the airflow.
Within seconds, you may be forced to tack away.
Meanwhile, another competitor who started two seconds late but in clear wind may already be gaining ground.
Similarly, the favoured end of the starting line may offer an advantage, but only if you can reach it with space and speed.
A crowded, heavily biased end may not always provide the best practical starting position.
This brings us back to the distinction between strategy and tactics.
Your strategy might be to start near the committee boat because that end is favoured and gives you access to the preferred side of the course.
Your tactics determine whether you can actually achieve that start without becoming trapped by other boats.
Time-on-distance helps you execute the plan.
It does not replace the plan.
15. Personal Reflections — Learning to Start a Different Boat
One of the most interesting things about sailing is that experience in one boat does not automatically translate into perfect judgement in another.
A small training dinghy, an RS Toura and a Thames A-Rater can behave quite differently.
The same distance from the line may be comfortable in one boat and completely wrong in another.
A manoeuvre that takes only a few seconds in a small dinghy may require more preparation in a larger or more demanding boat.
For me, this is part of the attraction of sailing Champagne.
There is always something new to learn.
We can use experience to make an initial judgement, but the real understanding comes from sailing the boat, observing what happens and adjusting our approach.
I would like to make our starting performance more systematic.
Rather than simply deciding that a start felt good or bad, we can ask:
Did we cross the line on time?
Were we accelerating or already travelling at a useful speed?
Did we have clear air?
How long did it take us to reach our normal upwind sailing speed?
Could we have positioned ourselves differently?
These questions turn every race into an opportunity to improve.
And the wonderful thing is that none of this requires expensive equipment.
A stopwatch, a few fixed reference points and a willingness to practise can teach you an enormous amount.
16. Five Things to Remember at Your Next Start
Distance alone is not enough. You need to consider speed and acceleration.
A moving start is often better than a stationary one. Arrive with the boat already sailing efficiently whenever conditions and tactics allow.
Current matters. On a river, your speed over the ground may differ considerably from your speed through the water.
Leave yourself options. A perfectly timed approach is of little use if another boat blocks your route.
Practise in your own boat. There is no substitute for learning how quickly it accelerates and how much space it needs.
Conclusion — The Race Begins Before the Starting Signal
A good start is not simply about being in the right place.
It is about being in the right place, at the right time, travelling at the right speed, with enough freedom to sail the first leg effectively.
That requires judgement, practice and an understanding of your boat.
Time-on-distance provides a framework for making those judgements.
The mathematics is simple. The sailing is more complicated.
And that is what makes racing so interesting.
Whether you are sailing a small club dinghy or a Thames A-Rater such as Champagne, improving your starts is one of the most rewarding ways to improve your racing.
Next time you are waiting for the starting signal, look beyond the boats already sitting on the line.
Watch the boats approaching from behind.
One of them may have judged the distance, speed and timing almost perfectly.
And when the starting signal sounds, it may already be sailing away.
The perfect start begins before the starting gun.
Read more about sailing, racing and our adventures aboard Champagne at PMR Sailing.
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