The short version
- What it is
- Two marks side by side at the bottom of the run. You sail between them and round either one.
- Which way round
- Looking upwind, the left mark is rounded to starboard and sends you off on starboard tack to the left; the right mark is rounded to port and sends you off on port tack to the right.
- How to choose
- In order: the side of the course you want next, which mark is further upwind, and where the traffic is.
- Decide early
- Make the call with a few hundred metres of the run to go, so you can set up a wide-in, tight-out rounding at the mark you picked.
What a gate is for
At a single leeward mark the whole fleet funnels into one spot, and the boats on the outside of a pack lose places to the boats inside them without anyone doing anything wrong. A gate halves the crowd. It also gives every boat a free tactical choice: you can start the next beat on whichever side of the course you prefer, without having to tack straight after the rounding in someone's bad air.
The race committee sets the two marks roughly square to the wind, usually several boat lengths apart. The sailing instructions say the gate is a gate and which marks make it up.
Rounding each mark the right way
Come down the run, pass between the two marks from the direction of the previous mark, then round the one you've chosen. Each mark has its own correct direction, and it follows from the fact that you've come through the middle:
- The left-hand mark, looking upwind, is rounded to starboard. You turn to your right around it and leave close-hauled on starboard tack, sailing toward the left side of the course.
- The right-hand mark, looking upwind, is rounded to port. You turn left around it and leave on port tack, sailing toward the right side.
Coming down the run you're facing the other way, so the left-hand mark looking upwind is on your right. That's the moment people get confused; settle it before you get there.
Check the sailing instructions. The 2025–2028 racing rules leave more of how a gate is treated to the sailing instructions than earlier editions did. Most use the arrangement above, but read how your event describes it, including what happens if the committee replaces the gate with a single mark.
1. Which side do you want next?
This is usually the deciding question. If you think the left side of the next beat will pay — more wind there, a shift coming from that side, less current — round the left mark and leave on starboard. If you want the right, round the right mark and leave on port. Either way you start the beat already going where you want to go, with no tack straight after the rounding.
The wind is the thing to watch here, and what to do depends on what kind of shift it is. See Playing the shifts for the full picture; for the gate, the short version is:
- An oscillating breeze (swinging back and forth): leave on the lifted tack. If the wind has veered — swung clockwise, say from 000° to 010° — starboard is lifted, so the left mark sends you off on the right tack. If it has backed, port is lifted and the right mark is the one.
- A persistent shift (the wind steadily moving one way, such as a sea breeze filling in): head toward the side the wind is shifting to. A wind that keeps veering favours the right side; one that keeps backing, the left.
Those two can point to different marks for the same shift, which is exactly why it's worth knowing which kind of day you're having before you reach the bottom of the run.
2. Which mark is further upwind?
A gate is a short line, and like a start line it's rarely exactly square to the wind. The mark that's further upwind is closer to the windward mark, so rounding it starts the next beat a little ahead. The same arithmetic as the favored end of a start line applies: gain = gate width × sin(skew).
Gates are narrow, so the gain is usually small: on a gate 50 m (165 ft) wide, a 10° skew is worth about 9 m (29 ft), and 5° about 4 m (14 ft). That's real, but it's easily outweighed by the side of the course you want or by a crowd at the favored mark. Two things make it bigger: a wide gate, and a wind shift since the gate was laid. A veer moves the upwind end of the gate toward the right-hand mark; a back moves it toward the left.
You can judge it by eye as you approach: look across from one mark to the other and ask which one is ahead of square to the wind. Boats rounding each mark and heading up the beat show it too — if the ones leaving one mark are consistently ahead, that end is favored.
3. Where's the traffic?
If a pack is heading for one mark and the other is quiet, the quiet one is often worth more than a small geometric gain. Rounding on the outside of three boats costs you far more than the few metres a skewed gate gives the other mark. A few things to keep in mind:
- Each gate mark has its own zone and the mark-room rules apply there. Boats heading for different marks generally aren't rounding the same mark, so the inside overlap only matters among boats going for the same one. See Mark-room.
- Don't change your mind late. A boat that swerves from one mark to the other in the last few lengths usually ends up badly set up for both.
- Set up wide in, tight out at the mark you choose, exactly as at a single leeward mark. See How to round a mark.
- Mind the boats behind on the next beat. Leaving one mark on port and crossing boats that rounded the other on starboard is a port–starboard situation like any other. See Port vs starboard.
Doing it with Sail Tactician
Questions
What is a leeward gate in sailing?
Two marks set side by side at the bottom of a run. Boats pass between them and round either one, then start the next beat.
Which way do you round a gate mark?
Looking upwind, the left-hand mark is rounded to starboard and the right-hand mark to port. You come through the middle of the gate first, then turn around the mark you've chosen.
How do you choose which gate mark to round?
First by the side of the course you want for the next beat, then by which mark is further upwind, then by where the other boats are going. A big crowd at one mark often outweighs a small geometric gain.
Does mark-room apply at a gate?
Yes, each gate mark has its own zone. Boats heading for different marks aren't usually rounding the same mark, so the overlaps that matter are between boats going to the same one.
What if the committee replaces the gate with one mark?
The sailing instructions say how that's signalled and which way to round the single mark. Read them before the race.
Sources
Gates, mark-room and sailing the course from the Racing Rules of Sailing 2025–2028 (rule 18 and the definition Sail the Course), described in our own words; event-specific treatment of gates is set by the sailing instructions. The gain formula is the same trigonometry as start-line bias. Tactical choices from standard club-racing practice. Sail Tactician behaviour from the in-app User Guide, version 3.2.
What changed
- First published.
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