A barkentine is a sailing vessel of three or more masts carrying square sails on the foremast only and fore-and-aft sails on all the masts behind it. The rig took commercial hold in the 1860s, with British and Baltic timber traders adopting it heavily — Gustaf Erikson's Åland fleet ran barkentines well into the 1930s. The square foremast drives the ship downwind while the gaff or Bermudan main and mizzen let a small crew work the boat upwind. The result is a hull that crosses oceans on trade winds yet still tacks into a harbour with 8 to 12 hands instead of 25.
Barkentine Sail Area Distribution Interactive Calculator
Compare foremast, main, mizzen and headsail areas on a barkentine rig. The 35–42% output is an example comparison, not a rig-design rule.
Equation Used
The calculation divides square-rigged foremast area by total sail area. Values from about 35 to 42 percent indicate the article's working barkentine balance range.
- All sail areas use the same units.
- Foremast area is square canvas only.
- A 35 to 42 percent square-sail fraction is treated as the working barkentine target range.
A barkentine is identified by its rig arrangement, not by a mandatory square-sail-area percentage. The retained 35–42% band is an example comparison.
Barkentine Rig Arrangement
The foremast carries square sails on yards. The main and mizzen carry fore-and-aft sails, shown here as gaff sails and topsails. Headsails run from the forward stays. Hiscox item 782 identifies this arrangement; the adjacent bark drawing carries square sails on the mainmast as well.
The area inputs change the represented sail groups. Gentle roll and canvas movement explain the arrangement without simulating vessel response to wind.
Industries That Rely on the Barkentine
The barkentine survived as a working rig because it solved a specific commercial problem — long downwind passages with small crews — and that same problem still exists in sail training, charter work, and a handful of niche cargo revival projects. You'll see the rig today on heritage vessels, expedition ships, and a growing fleet of sail-cargo boats trying to move wine and cocoa across the Atlantic without a diesel.
- Sail training: The Gazela Primeiro, a 1901 Portuguese barkentine still sailing out of Philadelphia, runs trainee crews under a traditional gaff main and square fore.
- Heritage cargo revival: TransOceanic Wind Transport's Avontuur — though technically a schooner — operates alongside revived barkentine projects like the Tres Hombres for wind-powered Atlantic cargo.
- Expedition charter: The Antigua, a 1957 barkentine refitted in 1993, carries paying passengers to Svalbard and Antarctica each season.
- Maritime museums and tall ships: The Pogoria, a Polish-flagged 1980 barkentine, sails as a youth training vessel and tall-ships race entrant.
- Coastal trade and timber: Historic Baltic and North Atlantic timber trade — Gustaf Erikson's fleet ran barkentines like the Lawhill and Penang on the Australian grain run into the 1930s.
- Film and historical reproduction: Built and rigged barkentines stand in for 19th-century merchantmen in productions where a full barque would be too crew-heavy to operate.
Compare Sail Areas
Square-sail share = 100 × Afore / (Afore + Amain + Amizzen + Ahead). In this example, the foremast group is square canvas; the main, mizzen and headsail groups are fore-and-aft canvas.
The retained 35–42% comparison band is an example, not a defining range or an optimum established for all barkentines. The calculation does not locate the centre of effort or predict sailing balance.
Worked Example: Barkentine in a 38 m sail-training barkentine refit
Your yard is rerigging a 38 m steel-hulled barkentine built in 1948 for a Norwegian sail-training charity. Hull displacement is 320 tonnes, draft 3.8 m, and the original sail plan totals 720 m². The foremast carries a course, lower topsail, upper topsail, topgallant, and royal totalling 280 m². The gaff main plus main topsail come to 195 m². The mizzen is 130 m². Headsails — flying jib, outer jib, inner jib, fore staysail — total 115 m². You need to confirm the square-area fraction lands inside the 35 to 42 percent working window before signing off the sail plan.
Given
- Afore = 280 m²
- Amain = 195 m²
- Amiz = 130 m²
- Ahead = 115 m²
Solution
Step 1 — sum the total sail area:
Step 2 — at the nominal sail plan, compute the square-area fraction:
That's 38.9 percent — squarely inside the 35 to 42 percent working window. Downwind in trade-wind conditions she'll log 8 to 9 knots in 20 knots true, and on a beat into 15 knots true she'll hold around 55 to 60 degrees off the wind. That's the sweet spot a 1948 Baltic-trade hull was designed for.
Step 3 — at the low end of the typical range, suppose the owner wanted to strip the topgallant and royal to simplify aloft work, dropping Afore to 200 m²:
At 31 percent the ship effectively becomes a topsail schooner. Upwind performance improves marginally — maybe 3 degrees closer to the wind — but downwind speed in the trades drops by 1.5 to 2 knots, which on a 3,000 nautical mile passage costs you four to six days. That's the difference between a 25-day Atlantic crossing and a 30-day one.
Step 4 — at the high end, suppose a previous owner had added a skysail and stunsails pushing Afore to 360 m²:
At 45 percent she's pushing toward a full barque's behaviour. Downwind she's quick, but reaching in 30 knots she'll bury the lee rail and you'll need to hand the upper square sails before the wind hits 25 knots true. The crew workload aloft also climbs — you'd need 14 hands minimum on watch to reef cleanly, defeating the whole point of choosing a barkentine.
Result
The nominal sail plan gives fsq = 0. 389, which means 38.9 percent of total canvas is square — bang in the middle of the working window for a steel-hulled trader of this vintage. That fraction translates to a ship that runs the trades fast, points respectably upwind, and works with a 10 to 12 hand watch instead of the 18 you'd need on a barque of equivalent displacement. Compared to the 31 percent low-end scenario she gives up 3 degrees of upwind angle but gains 1.5 to 2 knots downwind, and compared to the 45 percent high-end scenario she's far easier to reef in a building breeze. If the rerigged ship handles worse than the calculation predicts — gripes hard upwind, won't bear off in a squall, or tracks badly downwind — check three things in order: (1) main and mizzen mast rake out of spec, often 5 degrees aft instead of the 2 to 4 the original plans called for, which shifts the centre of effort too far aft; (2) headsail luff tension slack, letting the jibs sag to leeward and stalling the lee bow; (3) yard brace geometry on the foremast off by 5 degrees or more from square, which kills downwind drive even with the right sail area.
When to Use a Barkentine and When Not To
The barkentine sits between two well-known rigs — the full barque and the topsail schooner. Choosing between them comes down to crew size, intended passage profile, and budget. Here's how they line up on the dimensions that actually matter when you're sizing or buying a vessel.
| Property | Barkentine | Barque (full square on fore + main) | Topsail schooner |
|---|---|---|---|
| Minimum working crew (30 m vessel) | 8 to 12 | 18 to 25 | 6 to 10 |
| Closest point of sail (true wind) | 55 to 60° | 65 to 70° | 45 to 50° |
| Downwind speed in 20 kt trades | 8 to 9 kt | 9 to 10 kt | 6 to 7 kt |
| Standing rigging cost (relative) | 1.0× | 1.4× | 0.7× |
| Aloft work hours per sail change | 2 to 3 | 5 to 7 | 1 to 2 |
| Best application | Long trade-wind passages with small crew | Maximum downwind speed, training large crews | Coastal trade, weatherly passages |
| Standing rigging inspection interval | 12 months working / 6 months charter | 12 months working / 6 months charter | 12 months working / 6 months charter |
Frequently Asked Questions About Barkentine
That's classic excess weather helm and on a barkentine it almost always traces back to the after sail being too powerful relative to the foremast. When the wind builds, the gaff main heels the ship and the centre of effort climbs and shifts aft, dragging the bow up.
The fix is to reef the main one panel before you reef anything forward, or scandalise the gaff (drop the peak halyard so the sail luffs from the head down). If reefing the main doesn't fix it, check that someone hasn't cranked the topping lift too tight — a tight topping lift bags the leech and increases heeling moment without adding drive.
Gaff keeps the centre of effort low, which suits a heavy-displacement hull and lets you carry sail longer in a building breeze. Bermudan points 5 to 8 degrees higher upwind and is simpler to handle shorthanded, but it raises the centre of effort and increases heeling moment in gusts.
Rule of thumb: if the hull's ballast ratio is below 35 percent, stay with gaff. Above 40 percent and you can get away with Bermudan. Between those numbers, look at what the original designer drew — they usually got it right for that hull form.
Sail area on paper isn't the same as effective driving area. The most common cause of underperformance at a correct fsq is yard brace geometry — if the braces lead too far forward on deck, you can't square the yards properly when running and the upper sails blanket the lower ones.
Measure the angle of each yard relative to the centreline at full brace-aft. You want the course yard at 90° to the wind on a dead run and the yards above progressively trimmed by 2 to 3 degrees each to clear the air. If the topgallant yard can only brace to 75 degrees, you're losing roughly 15 percent of upper-sail drive.
It can run dead downwind — that's the whole point of the square foremast. Unlike a pure schooner, you don't need to tack downwind in a series of broad reaches because the square sails draw cleanly with the wind from astern.
In practice you'll sail 5 to 10 degrees off dead downwind to keep the main and mizzen filled rather than slatting, but you don't gybe back and forth across the rhumb line. This is why barkentines were the dominant trade-wind cargo rig for 70 years.
Roughly 24 to 26 m on deck is the lower bound. Below that, the foremast becomes too short to carry enough square sails to justify the complexity — you end up with a course and a single topsail, which a topsail schooner does just as well with half the rigging.
The other limit is yard handling. A course yard under about 8 m long can be managed by 2 hands; below 24 m hull length the yards become so short the sails are postage stamps and you've added the cost of square-rig hardware for very little driving force. This is why you almost never see a 20 m barkentine — the rig only earns its keep at scale.
The foremast on a barkentine takes asymmetric loading the main and mizzen don't see — square sails pull forward and the headsails pull forward and down through the bowsprit. If the forestay and jibstay tensions aren't matched, the mast walks every time the ship pitches.
Check the tension ratio: forestay (mast to bowsprit cap) should sit about 15 percent higher than the inner jibstay. If they're equal, the bowsprit lifts in a head sea and the whole foremast starts pumping. A pumping foremast will fatigue the partners at deck level and crack the mast step inside one ocean passage.
The chainplates and the partners on the foremast. Chainplates corrode where they pass through the deck and you can't see the damage without pulling them — a vessel that's been sitting in fresh water for a winter can hide 40 percent section loss under fresh paint.
Replacement on a 30 m barkentine runs 30,000 to 60,000 USD and typically requires hauling out and dropping the foremast. Always insist on a chainplate inspection — pull at least the two forward shroud plates and the forestay plate — before you sign anything. Everything else on the rig is cheaper to fix than chainplates.
References & Further Reading
- Wikipedia contributors. Barquentine. Wikipedia
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