The Start Line — Why One End Can Be Much Better Than the Other
PMR Sailing | Learning to Race — From First Start to Better Results | Sailing Tactics Series
“A ten-degree wind shift can make one end of the start line remarkably valuable. And on a river, where the starting line may be surprisingly short, those few degrees can make the difference between leading the fleet and spending the first beat trying to catch up.”
One of the fascinating things about sailing is that two boats can cross the starting line at precisely the same moment, both travelling at the same speed, yet one can already have a significant advantage.
How can that possibly happen?
The answer is often start-line bias.
When we first learn to race, we tend to concentrate on getting across the line at the correct time. We watch the countdown, try to avoid other boats and hope we are not over the line early.
As our racing improves, we begin to realise that simply crossing the line at the starting signal is only part of the challenge.
Where we cross can be just as important.
At Upper Thames Sailing Club, where we race on the River Thames between Bourne End and Marlow, the geography makes this particularly interesting. The river is relatively narrow, the banks are lined with trees, and the wind is rarely as consistent as we might wish.
A starting line that looks perfectly reasonable from the bank can offer quite different opportunities at its two ends.
And when racing a boat such as our A-Rater Champagne, the decisions become particularly important. A fast boat can exploit a good starting position, but a poor start can leave even a quick boat trapped in disturbed air.
Let's explore why.
1. What Exactly Is Start-Line Bias?
A sailing race usually begins between two points: commonly a committee boat or shore-based starting position at one end, and a buoy or another fixed mark at the other.
Ideally, for a conventional upwind start, the line would be set at 90 degrees to the true wind direction.
That would mean neither end was geometrically closer to the windward mark, assuming a reasonably uniform wind.
However, the wind does not always cooperate.
It may shift after the line has been laid. On a river, it may bend around trees, buildings and bends in the bank. The race officer may also have limited options for positioning the line.
The result is a starting line that is not quite square to the wind.
One end is effectively further upwind than the other.
This is what sailors call a biased starting line.
Imagine that the left-hand end of the line is 10 metres further upwind than the right-hand end.
A boat starting at the left-hand end has already gained those 10 metres of upwind position before either boat has sailed the first leg.
That does not guarantee victory, but it is an advantage worth recognising.
2. How Much Difference Can Ten Degrees Make?
Ten degrees sounds insignificant.
If you were steering a boat and altered course by ten degrees, you might barely notice the change on a broad river.
Yet the geometry can be surprisingly important.
For a starting line of length L, angled by B degrees away from being perpendicular to the wind, the approximate upwind difference between its ends is:
Upwind advantage = L x sin(B)
Here are some illustrative figures.
Starting line length | 5° bias | 10° bias | 15° bias |
|---|---|---|---|
30 metres | 2.6 m | 5.2 m | 7.8 m |
50 metres | 4.4 m | 8.7 m | 12.9 m |
80 metres | 7.0 m | 13.9 m | 20.7 m |
100 metres | 8.7 m | 17.4 m | 25.9 m |
These figures describe the upwind displacement between the ends, not necessarily the final distance gained at the windward mark.
Consider a 50-metre starting line with a ten-degree bias.
The favoured end is approximately 8.7 metres further upwind.
In a small racing dinghy, that can represent a substantial amount of progress. Even in a much larger boat, it is worth having.
And on a river, where opportunities to recover lost ground may be restricted by the banks, an advantage of a few metres can be extremely valuable.
But there is a complication.
The geometrically favoured end is not always the best place to start.
We will return to that shortly.
3. How Do You Know Which End Is Favoured?
Fortunately, there are several practical methods.
Method One — Sail Along the Starting Line
This is one of the simplest exercises for a developing racing sailor.
Before the start, sail reasonably close to the starting line, keeping clear of other competitors.
Establish the true wind direction by looking at your burgee, masthead indicator, telltales or the behaviour of the sails.
Now compare the line's orientation with the wind.
If the line is square to the wind, neither end has an upwind geometrical advantage.
If one end is further towards the wind, that is the favoured end.
It sounds easy, but on a river the wind may change considerably during the exercise.
What appeared to be the favoured end two minutes ago may no longer be favoured when the starting signal sounds.
Method Two — Point Directly Into the Wind
A useful method, especially for beginners, is to stop or slow the boat in a clear area and briefly point the bow into the wind.
Look at the direction of the starting line relative to the boat.
With the boat pointing directly upwind, the ideal square line would run directly across the boat, at right angles to its centreline.
If the actual line slopes towards you at one end, that end is generally the further-downwind end. The opposite end is favoured.
The important point is to use the actual wind direction, not simply the direction the river appears to run.
Method Three — Compare the Two Close-Hauled Headings
This is particularly useful for more experienced sailors.
Sail close-hauled on one tack, recording or remembering your heading.
Tack and sail close-hauled on the other tack.
These two headings help establish the true wind direction, assuming relatively steady wind and consistent boat performance.
The true wind direction will lie approximately halfway between the two close-hauled headings, allowing for compass wrap-around and any asymmetry in the boat.
Compare that direction with the starting line.
You can then judge which end is further upwind.
This method is especially useful when the wind is shifting and a single observation might be misleading.
4. Sighting the Line — Knowing Exactly Where It Is
There is another problem at the start.
From a low position in a sailing dinghy, it can be remarkably difficult to judge whether you are behind the starting line, on it or already across it.
The problem becomes more pronounced when other boats obscure the committee boat or starting mark.
One very useful technique is to sight the starting line.
Using a Transit
Before the start, sail close to an extension of the starting line, beyond one end, where it is safe and permitted.
Look along the line towards the opposite end.
Identify a fixed object on the bank that lines up with the two starting marks.
It might be a tree, a distinctive roof, a building or a gap between trees.
That object provides a visual transit.
As you approach the start, the transit helps you recognise the position of the line.
This is particularly useful when starting near an end of the line.
However, a transit established by looking along the line is most accurate when viewed from the same extension of the line. From elsewhere on the course, parallax makes it less reliable.
And, of course, on a river the trees can all look remarkably similar!
I would always recommend identifying something distinctive rather than simply choosing the largest tree.
What About the Middle of the Line?
Sighting becomes more difficult towards the centre because you cannot necessarily see along the line.
Here, experience, visual bearings, the position of other boats and judgement of distance become important.
A GPS position may help with navigation, but ordinary recreational GPS accuracy and display delay may be inadequate for judging a short starting line precisely.
For most club dinghy racing, good visual awareness remains essential.
5. Why Starting in the Middle Is Not Necessarily the Safest Choice
Many beginners instinctively aim for the middle of the line.
It seems sensible.
There is space to either side, you are not competing directly for the favoured end, and you are unlikely to become involved in a complicated battle around the committee boat.
Sometimes the middle is indeed an excellent choice.
But consider a fleet where most boats have recognised that the pin end is favoured.
Several competitors may converge on that end.
If you start in the middle, you may have more space, but you could be giving away several metres of upwind position.
Alternatively, the middle might be crowded while the committee-boat end offers clean wind and a clear lane.
The key is not to regard the middle as automatically good or bad.
Instead, ask:
Where can I cross the line at speed, at the correct time, with clean wind and a useful route towards the first mark?
That is a much better question.
6. The Favoured End Can Be a Trap
Imagine a starting line with a strong pin-end bias.
Every experienced sailor has noticed it.
With two minutes remaining, boats begin congregating near the pin.
By the final thirty seconds, there may be six or seven boats trying to occupy a space that comfortably accommodates only three.
Someone becomes trapped to leeward.
Another boat is forced to slow down.
A third loses steerage and cannot accelerate properly.
Meanwhile, a sailor starting further along the line crosses at full speed with clear wind and an unobstructed route.
Who has the better start?
Not necessarily the sailor at the favoured end.
This illustrates one of the most important principles in racing:
A theoretical advantage is only useful if you can actually exploit it.
Starting at the favoured end but stationary, with your sails flapping and another boat blocking your acceleration, can be much worse than starting five metres further down the line at full speed.
For beginners, I would usually recommend prioritising a clear, controlled start rather than fighting for the last metre of advantage.
As confidence develops, the tactical possibilities become more interesting.
7. River Racing Changes Everything
This is where racing at Upper Thames Sailing Club becomes particularly fascinating.
On open water, a starting line might be long enough for competitors to spread out.
On the Thames, the available width can be much more restricted.
The starting line may be relatively short, and the first leg may require immediate decisions about which bank to approach.
There are several additional factors.
Wind Shadows From Trees
One side of the river may be sheltered by tall trees.
The other side may have a clear opening through which stronger wind is reaching the water.
Suppose the pin end is geometrically favoured, but it lies in a substantial wind shadow.
The committee-boat end may be less favoured geometrically, yet offer significantly better wind.
In that situation, the apparently disadvantaged end could be the better starting choice.
A boat moving at four knots in clean wind may quickly overcome a few metres of geometric disadvantage compared with one struggling to accelerate in a wind shadow.
River Current
Current adds another dimension.
On a river, the current is not necessarily uniform across the channel.
It may be stronger in the deeper central section and weaker near the banks, with local eddies around bends and obstructions.
If the race begins against the current, the choice of starting position may affect how quickly you can reach a useful area of reduced flow.
If you are racing with the current, a different route may be preferable.
The important distinction is that current does not automatically change which end is geometrically upwind. Instead, it changes how quickly a boat can make progress over the ground and which route is advantageous.
A start-line decision should therefore consider both the wind and the water.
The First Tack
On a narrow river, you may have very little room before the bank forces a tack.
Suppose the favoured end puts you close to a bank where you will almost immediately have to turn.
If several boats are in the same position, the resulting congestion may destroy the advantage gained at the start.
Starting slightly further away might provide room to accelerate and sail a clean first leg.
This is a good example of the difference between start-line geometry and actual race strategy.
8. A Practical Example — Two Boats, Two Different Starts
Imagine a club race on a relatively narrow stretch of the Thames.
The starting line is 40 metres long and has a ten-degree pin-end bias.
The pin has an upwind advantage of approximately 6.9 metres.
Two boats approach the start.
Boat A — Pin End
Starts close to the favoured pin, but has to slow down behind another competitor. It crosses three seconds late.
Boat B — Middle
Starts with clear air, already moving at four knots, and crosses exactly at the signal.
At four knots, Boat B travels approximately 6.2 metres through the water in three seconds. Boat A has a 6.9-metre upwind geometric advantage, but its delay, lower speed and disturbed air may quickly eliminate that benefit.
Illustrative comparison. Distance sailed through the water is not identical to distance made good upwind, so the actual outcome depends on headings, acceleration and current.The lesson is that line bias matters, but it must be balanced against boat speed and the ability to sail freely.
9. Champagne — Why a Good Start Matters in a Fast A-Rater
Racing Champagne, our Thames A-Rater, introduces another level of interest.
An A-Rater is a very different proposition from a small training dinghy.
It is long, carries a substantial sail plan and relies on good coordination between the helm and crew.
With three people working together, the start is not simply a matter of the helm steering towards the line.
The crew must be ready for the acceleration, changes in sail trim and any last-minute manoeuvres.
The Cost of Losing Momentum
A performance boat benefits from maintaining flow over its sails and foils.
A poorly timed approach can leave the boat moving too slowly just as the starting signal sounds.
Recovering speed may take time and space.
On a river, neither is necessarily available.
For Champagne, I would rather approach a start with a clear plan and enough room to build speed than commit to a congested favoured end with no practical escape.
Crew Communication
A useful pre-start conversation might include:
Which end appears favoured?
Is that end crowded?
Where is the strongest wind?
Which side of the river do we want after the start?
When do we need to accelerate?
What is our alternative if another boat takes our intended position?
The helm cannot necessarily watch the countdown, assess every nearby boat, monitor the wind and plan the first tack simultaneously.
A well-organised crew can share those responsibilities.
And this is one reason why racing a three-person boat can be such an enjoyable learning experience.
Good decisions become a team achievement.
10. What Happens When the Wind Shifts Just Before the Start?
Suppose you have spent five minutes preparing for a pin-end start.
Everything looks perfect.
Then, with thirty seconds remaining, the wind shifts ten degrees.
The previously favoured end may become neutral or even disadvantaged.
What should you do?
The answer depends on how much time and space you have.
If there is enough time to reposition safely, changing your plan may be sensible.
If there are only fifteen seconds remaining and several boats are between you and the opposite end, attempting to cross the entire line may be disastrous.
Sometimes the best decision is to accept that the conditions have changed and make the most of the position you already occupy.
This is where the distinction between strategy and tactics becomes important.
Your strategy might have been to start at the pin and work towards the right-hand side of the course.
Your tactical response might be to remain where you are because moving would create an unacceptable risk of a poor start.
Good sailors make plans. Better sailors know when to adapt them.
On the Thames, where wind shifts can be frequent and localised, that flexibility is particularly valuable.
11. A Simple Start-Line Exercise for Club Sailors
This is an excellent exercise for sailors who want to improve their racing without becoming involved in complicated tactical situations.
It can also work well as a coaching activity.
Exercise — Find the Favoured End
Stage 1: Observe
Before the start, estimate the true wind direction and decide which end of the line is favoured.
Do not ask another sailor for the answer immediately.
Make your own judgement.
Stage 2: Test
Sail near the line and compare the headings available on each tack.
Does your original assessment still seem correct?
Stage 3: Consider the Alternatives
Now look at the wind strength, the current, the bank and the other competitors.
Would you actually want to start at the favoured end?
Stage 4: Make a Decision
Choose your intended starting position and a backup option.
Stage 5: Review
After the race, ask yourself:
Did I correctly identify the favoured end?
Did I start at the intended position?
Was I moving at speed?
Did the first tack work as planned?
Would a different position have been better?
This last stage is particularly valuable.
Without reviewing the result, it is easy to repeat the same mistakes every week.
12. Five Common Starting-Line Mistakes
1. Assuming the line is square to the wind. Even a small bias can matter, so check rather than assume.
2. Choosing the favoured end without considering traffic. A clear start a little further down the line can be better than being trapped in a crowd.
3. Ignoring wind shadows. The strongest and most consistent wind may be more valuable than a small geometric advantage.
4. Forgetting the first leg. A start is only useful if it puts you in a position to sail the next part of the course effectively.
5. Changing the plan too late. A last-second attempt to reach the opposite end can create more problems than it solves.
13. An Advanced Thought — Is the Favoured End Always the One Closest to the Windward Mark?
Not necessarily.
We have been discussing the geometrical advantage of starting further upwind.
But the shortest useful route to the windward mark is not always determined by that geometry alone.
Consider a course where the windward mark lies towards the right-hand bank.
The pin end may be favoured, but a boat starting near the committee end might have a better opportunity to reach the right-hand side of the course.
If that side has stronger wind, less adverse current or a favourable wind shift, it could be the better choice.
Conversely, a boat starting at the pin might be forced into a series of short tacks because of the bank or other competitors.
The result is that the theoretical upwind advantage may disappear.
This leads to a useful principle:
The best starting position is not necessarily the end furthest upwind. It is the position that gives you the best opportunity to sail the first leg well.
That is the point at which simply learning how to start develops into understanding racing strategy.
Conclusion — Win the First Decision, Not Necessarily the Start
One of the pleasures of sailing is that there is always another layer of understanding waiting to be discovered.
At first, we learn to cross the starting line without being early.
Then we learn to cross it at speed.
Next, we begin to recognise that the starting line may favour one end.
Eventually, we realise that the favoured end is only one part of a much larger tactical problem involving wind, current, competitors, geography and the first leg of the course.
At Upper Thames Sailing Club, those factors can be particularly interesting because the river creates such varied conditions.
A small wind shift, a gap in the trees or a patch of slower current can completely change the best approach.
And when racing Champagne, those decisions become part of the teamwork that makes sailing a fast A-Rater so rewarding.
The next time you prepare for a race, do not simply ask whether you can cross the line at the correct moment.
Ask yourself three questions:
Which end is favoured? Where is the best wind? And where do I want to be thirty seconds after the start?
If you can answer those questions before the starting signal, you are already beginning to think like a racing sailor.
In the next article in our Learning to Race series, we will look at how to approach the starting line at the right speed, judge time and distance, and avoid arriving either too early or too late.
Follow the series at PMR Sailing, where we explore sailing techniques, racing tactics and life aboard the Thames A-Rater Champagne.
Return to sailing website https://pmrsailing.uk/Lessons.html
