On this page:

1. Square-Rigged Ships Upwind Performance
2. Ship Handling Upwind
3. Optimized for the Trades
4. Smaller Ships and Upwind Sailing
5. Further Reading

Square-rigged ships were not the only vessels plying the seas, but they were the biggest and the fastest. With their size and speed optimizations, they posed many challenges on how best to sail, fish, fight, and explore from them.

Square-Rigged Ships Upwind Performance

In the age of sail, they divided the compass into thirty-two points, with each covering 11¼° of the compass. Seven points off the wind (7 * 11.25 = 78.75°) was the accepted normal upwind point of most square riggers. The reality was a little different, and getting a ship to sail that high took considerable effort. To get it up to six points (68.5°) was possible, with ever more effort and risk to the gear.

Extreme Rigging

Only some ships could rig their square sails to fill at six points off the wind. Using a "truss yoke" could pull the sails closer forward by a bracket on the truss, or slacking off the truss lines, which normally keep the yardarms close to the mast. Tightening the cat-harpins to pull the windward yard closer to the wind also helped. In more plain English - special hardware and extra tightening of certain support lines could move the sail enough upwind to fill with wind at six points.

Ship rigging and terminology is arcane and extensive, and confusing to the modern sailor used to just two sails and the few lines and halyards needed to move a modern sloop. A few important terms may make it more clear - look at the diagram below to find a few examples of these parts.

A square sail hangs from a yard or yardarm and connected to the yard below them. This, like almost any pole or stick on the boat, may also be called a spar. Crews controlled the angle of attack of the sail by the braces, and the yard is rigged at the trusses to pivot around the mast.

The naming convention was usually (mast) + (sail) + (function). So the "fore royal yard" is the yard on the foremast that the royal (topmost sail) hangs from.

This was not without risk - it put a lot of strain on the yards as they turned the sails towards the wind and sheeted as flat as possible. Broken rigging, "sprung" spars, and torn sails were a constant risk. Once the rig was trimmed for tight upwind sailing, then the hard part had to be done.

Rock stars at the Helm

Beating upwind in a race in a small sloop is a challenge. You're sailing the boat on the edge of slipping into irons, sailing off the telltales to keep them fluttering just-so with a light touch on the wheel to keep from over steering or pinching up and slowing the boat.

Now, imagine doing the same with a full-keeled, massive sailing ship with a dozen sails, a less than responsive steering wheel, and no instruments. Keeping a full-rigged ship on the edge of sailing upwind was a very skilled task which relied as much on feel and intuition as any sort of guidelines or instruments.

Steering a ship across or down the wind to a compass heading was comparatively easy. But compasses in those days weren’t accurate enough to sail to the wind with.
So when upwind sailing mattered most, just like a modern racing crew at the start, the captain put the best driver on the helm. Histories tell stories of cooks and ship's surgeons who had the "best feel" on the helm being drafted to sail the boat in critical situations like getting off bad shores or pursuing an enemy.

Realistic performance numbers

Given the challenges of rigging and sailing hard on the wind, sailing six points off the wind (67.5°) is optimistic for most old ships, and impossible for many. Some small vessels with fore-and-aft rigs could certainly sail upwind better than square-rigged ships, but for the larger merchant vessels and warships, this was very difficult.

With some ships struggling to sail much above 80°, current could make upwind sailing close to impossible. A knot of two of current coming from the same direction as wind, coupled with a ship's normal leeway, resulted in days or even weeks spent trying to cross small, unfavorable patches of water.

Ship Handling Upwind

Modern sloop rigs are easy to tack across the wind, and it's rare that we blow a tack and end up in "irons" - or stuck with the bow facing upwind and unable to fill the sails. If we do, the small boats are light enough that they drift back on the wind in a few minutes, or we can use the engine on heavier boats or body English and ooching in dinghies.

Putting a tall ship into irons was a completely different affair. A two-decked, third-rate seventy-gun ship of the line in the British Navy in the 18th century might weigh 1,500 tons or more. The famed forty-four gun U.S. frigate Constitution displaced 2,200 tons. While merchant vessels tended to be smaller, they still displaced many hundreds of tons.

You did not want to put one of these ships in irons.

Tacking a square rigger is possible, but it's a delicate procedure, and if you "miss your stays" you may end up irons for hours as the sails flog and the boat slows to a stop. The for-and-aft sails are the primary driver through a tack, and may be back-winded to help the boat around as they bring the yards around to the other side of the ship.

The safer, but much slower, alternative to tacking is "wearing ship," which in modern terms is a jibe through almost 240° to end up on the other tack. If immediate speed is not an issue, wearing ship is often a better choice as it's easier and reduces the chances of rig damage or crew injury, especially in high winds.

Optimized for the Trades

The primary strategy for handling upwind sailing with a square-rigged ship was to avoid it. These ships project a massive amount of sail area and were designed to be fastest off the wind. Rather than pick a point on the horizon and sail for it, the entire strategy of sailing across oceans tilted towards picking a route where the wind was mostly at your back.

On the Atlantic ocean in the Northern hemisphere, two large standing wind patterns dominate northerly and tropical waters. The northeasterly trade winds blow almost constantly south of 30° in the summer and 25°N in the winter, allowing for predictable downwind sailing in the southern latitudes. In the north Atlantic, westerly winds predominate, though they are not as reliable as the trades they can be counted on to dominate the sailing conditions.

By sailing south for westward passages and north for eastward passages, navigators could plan on mostly downwind sailing and reaching, avoiding the worst of the slow upwind beating.

Smaller Ships and Upwind Sailing

We've mostly addressed the really large sailing ships from the past - the square riggers and warships most think of from the age of sail. But "ship" from that period explicitly meant a ship-rigged vessel. Not a barque, barquentine, schooner, clipper, or any of several rig styles we call a "sailing ship" in modern parlance.

Some of these rigs, especially the smaller ones, had many more fore-and-aft rigged sails, or all fore-and-aft sails,, and could sail upwind considerably better than the ships, barques, brigs and other square-rigged vessels. But these were lighter ships with finer hulls, and not designed to carry the vast weight of cargo and weaponry as the larger square riggers.

While schooners, gaff cutters and ketches, and other classic rigs may not point with a Bermuda rigged sloop, these rigs are efficient enough and manageable upwind. Modern sailors with a preference for the classic beauty of these rigs and wooden boats keep them alive and sailing.

Further Reading

For additional information on ship rigging, performance, and terminology, explore these links.

https://www.cnrs-scrn.org/northern_mariner/vol13/tnm_13_4_29-39.pdf
https://www.hnsa.org/manuals-documents/age-of-sail/textbook-of-seamanship/rigging-ship/
http://www.ageofsail.net/aostermi.asp