How to Judge Laylines When the River Isn’t Straight

Laylines are tidy, elegant things on open water. Draw two straight lines from the mark, sail to one of them, tack once, arrive looking smug.
Rivers, however, did not get that memo.

On the Thames (and most inland rivers), the course bends, the banks pinch in and out, trees mess with the wind, and the “obvious” layline often leads you neatly into trouble. Learning to judge laylines on a twisting river is less about geometry and more about anticipation.

First: what a river does to your assumptions

On a river, three things quietly undermine textbook laylines:

• The river bends – the mark may be upwind now, but relative to the next reach it won’t be.

• Wind shifts with the banks – the wind near one bank may be lifted, while the other is headed.

• The stream matters – even gentle flow changes angles and time-on-tack.

If you sail a river as if it were a straight beat, you usually end up overstanding, underpowered, or parked in bad air under the trees.

Look beyond the mark

Instead of staring at the buoy or turning mark, look past it:

• Which way does the river turn after the mark?

• Which bank will you want to be on next?

• Where is the wind likely to bend or lift?

Often the “best” layline is deliberately late or early so you exit the mark already set up for what comes next.

The golden river rule: avoid the early layline

On rivers, an early layline is usually a trap.

Why?

• You lose flexibility.

• Any header means two extra tacks.

• You risk being pinned against a bank with nowhere to go.

It’s usually better to sail slightly inside the layline, keeping options open, especially as the wind funnels and twists near bends.

Watch the banks, not just the sails

River sailing rewards observation:

• Upwind bank: often gives lifted wind but more turbulence.

• Leeward bank: steadier wind but may be headed.

• Tree gaps and buildings: wind accelerates through them.

If boats ahead suddenly tack and look happier, they’ve probably just found a bend-induced shift — that’s your moving layline revealing itself.

Think in curves, not straight lines

A useful mental trick:
Don’t imagine straight laylines — imagine curved corridors that move with the river.

As you approach the mark, ask:

• “If the river bends left, will this tack still work in 30 seconds?”

• “Am I sailing toward future space, or into a dead end?”

Good river sailors are constantly adjusting the layline in their heads as the picture evolves.

The quiet skill: arriving slow but correctly placed

On rivers, arriving at the mark perfectly powered but on the wrong side is worse than arriving slightly slow but well placed.

A gentle final approach, with one last short tack if needed, often beats charging in on a rigid layline and having nowhere to go.

In short

Judging laylines on a river isn’t about precision — it’s about reading ahead.

• Delay committing.

• Watch how the river bends.

• Treat laylines as flexible, moving targets.

• Prioritise exit position over textbook angles.

On a river, the sailor who looks past the mark nearly always beats the sailor who stares at it.