The quarter is the aft part of each side of a boat, roughly the section between the widest point of the hull and the stern. Boats have a port quarter and a starboard quarter, and a great deal of sailing happens over them: the helm sits there, the wind comes over one of them on a broad reach, and following seas arrive over them when you are running. Beginners learn “on the quarter” as a direction – something bearing about 45° abaft the beam. Experienced sailors know that a quartering sea is the hardest to steer in, that the quarter wave tells you when the boat is being pushed too hard, and that a wind on the quarter is where a well-designed asymmetric spinnaker or reacher earns its keep.
Where the quarter is
Divide a boat’s side into thirds. The forward third is the bow, the middle third is the beam or midships, and the aft third is the quarter. As a bearing, “on the port quarter” means somewhere between abeam and dead astern on the port side, centred on about 135° relative to the bow. A vessel “broad on the quarter” is well aft; one “fine on the quarter” is nearly astern. Along with bow, beam and astern, quarter completes the set of relative bearings that lets a crew report a sighting without giving a compass number.
Wind on the quarter: the broad reach
When the wind comes over the quarter you are on a broad reach, typically a true wind angle between about 120° and 160°. It is a fast, comfortable point of sail on most boats and the one where sail design matters most, because the apparent wind is lighter than the true wind and moves aft as the boat slows. The genoa loses power behind the mainsail and wants either a pole to hold it out or replacing with a downwind sail. This is asymmetric spinnaker and reacher country: a sail with a deep, forgiving luff that flies from a tack line at the bow and sheets aft to a block right on the quarter. UK Sailmakers cuts its asymmetrics so the luff projects to windward of the bow and the shoulders stay stable as the boat rolls, because a sail that collapses every time the quarter lifts on a wave is neither fast nor restful.
A symmetric spinnaker on a quartering wind is squared back so the pole sits roughly perpendicular to the apparent wind, with the sheet led to a quarter block to open the leech. The mainsail is eased until it is just short of luffing at the shrouds, the vang is on hard enough to control twist, and a preventer on the boom guards against an accidental gybe if a wave slews the stern round.
Quartering seas
A quartering sea is one that arrives at the boat over the quarter rather than from ahead or astern. It is uncomfortable because each wave lifts the stern and tries to push it sideways, so the boat yaws towards the wind as the crest passes and falls back as it goes by. In a steep quartering sea the risk is a broach: the stern is slewed round faster than the rudder can correct, the boat rounds up, heels hard and the spinnaker or mainsail pins her down. The defences are speed (a fast boat is steered by the water flowing past the rudder, a slow one is steered by the wave), a reduced and well-controlled sail plan, a firm vang and preventer, and an alert helm who anticipates each wave by bearing away slightly as the stern lifts and heading back up as it passes.
Cruisers often find that altering course 10° or 20° so the sea comes more from directly astern or more from abeam makes a quartering sea far easier to live with, even at the cost of a longer route. Autopilots steer badly in quartering seas; hand steer, or set the pilot to wind angle rather than compass course so it follows the shifts.
Frequently Asked Questions about Quarter
Where exactly is the quarter on a boat?
The aft third of each side, from about the widest point of the hull back to the stern. There is a port quarter and a starboard quarter.
What does “wind on the quarter” mean?
The wind is coming from behind and to one side, roughly 45° abaft the beam. That is a broad reach, generally the point of sail for asymmetric spinnakers, reachers and squared-back symmetric spinnakers.
Why is a quartering sea so hard to steer in?
Each wave lifts the stern and shoves it sideways, so the boat yaws with every crest. Keeping speed up, reducing sail, using a preventer and steering actively to each wave all help; so does altering course so the sea is more directly astern or abeam.
The quarter is where the wind and the sea meet a boat when she is going fast downwind, and where a helm learns most about steering. Know your quarters as a place on the boat, as a direction over the water and as a point of sail, keep the boat moving when the sea is on them, and they become the most enjoyable angle in sailing rather than the most nervous.