J/121
3C COMPOSITE · Rod Johnstone · 2017
Updated
The J/121 is a 12.19 m semi-displacement racing yacht designed by Rod Johnstone and built by 3C COMPOSITE, first launched in 2017. It races in Class A. Across the measured fleet it goes better than its own numbers promise, ahead of 56% of the designs it races against. It comes alive as the breeze builds, and gives time away in the light.
Goes better than its own measurements promise, and does it better than 56% of the boats it races against.
21st of 46 in its class.
This design has been found in real race results — 20 starts across 6 events — not only in measurement files.
Length
12.19 m
40′ 0″
Beam
3.75 m
Draft
2.36 m
Displacement
6.2 t
Sail area
89 m²
On the podium
Where a J/121 finishes when she goes racing.
On the podium
40%
of 20 starts by 5 boats
Wins
5%
Read from 20 starts by 5 boats between 2024 and 2026, counting races with six boats or more.
Recent regattas
The latest events where a J/121 was on the start line, named as the organisers publish them.
Aegean 6002026
North Sea Regatta2026
Rolex Middle Sea Race2025
GBCA ORC Championship2025
Swedish Offshore Double Handed Championship for ORCi2025
Raced one we are missing?
Report a regattaRound the buoys, or offshore
A short windward-leeward and a night at sea ask different things of a boat. Here is how this one does in each.
Round the buoys
—
Not enough data yet: 8 races of 10 NM or less carry a published distance.
Offshore & coastal
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Not enough data yet: 5 races over 10 NM carry a published distance.
Who she races against
The designs a J/121 actually lines up with, most often first. The bar shows how those meetings ended.
Also met, too few times for a figure:
Arcona 380 (6 meetings), JPK 10.80 (6 meetings), Figaro 2 (5 meetings), J/99 (5 meetings), Albin Nova (4 meetings), X-302 (4 meetings), First 34.7 (4 meetings), Dehler 41 (Judel/Vrolijk) (4 meetings), J/109 (4 meetings), First 40 (3 meetings), Melges 24 (3 meetings), J/124 (3 meetings), First 36.7 (3 meetings), J/105 (3 meetings), Landmark 43 (2 meetings), Sydney 46 (2 meetings), Mat 107 (2 meetings), J/112 (2 meetings), Grand Soleil 43 (Carkeek) (2 meetings), Ker 46 (2 meetings), Luffe 400 (2 meetings), J/122 (2 meetings), W 60 (2 meetings), Pac 52 (2 meetings), JPK 10.30 (5 meetings), Cookson 50 (3 meetings), Elan 450 (2 meetings), HH 42 (2 meetings), Sun Fast 3300 (Andrieu) (2 meetings)
Some of the boats it races against
How the J/121 has fared against each of them, boat against boat on corrected time. Ordered by how often the two meet, not by who wins.
Speed at every angle
The shape of this design's speed, drawn from the measured fleet. Pick a wind and watch it stretch.
Upwind VMG
5.99
37°
Beam reach
9.67
90°
Broad reach
12.02
135°
Downwind VMG
9.17
170°
Speed in knots at 20 knots of true wind. Green marks the angles that pay: the closest useful beat and the deepest run worth sailing.
Where it wins and where it pays
Every boat is judged against its own measurements — length, weight, sail area. The quicker those say it should be, the more it has to deliver just to break even. Going fast is not enough: it has to go faster than its own numbers promised.
This is a boat that wants breeze. On a windy coastal course it is in its element; on a light-air windward-leeward it has to be sailed well to hold on.
Where it gains
Its best ground is on a broad reach once it pipes up, where it goes better than its measurements say it should, and by a margin worth having. It holds that advantage running deep as well, so the gain is not down to one leg of the course.
Where it pays
There is no condition where it falls away badly, which is worth something over a season of mixed weather.
Above the line it delivers more than promised and gains on the fleet. Below, it falls short. Move the wind: plenty of boats sit on one side in the light and the other when it blows.
Full width is 1.2 kn either way.
At 10 knots this design makes back more than its rating asks on the broad reach.
How fast is a J/121
Boat speed in knots, by true wind angle and wind strength.
| Angle | 6 kn | 10 kn | 14 kn | 20 kn |
|---|---|---|---|---|
| Beat VMG | 3.84 | 5.32 | 5.83 | 5.99 |
| 52° | 5.86 | 7.64 | 8.12 | 8.32 |
| 60° | 6.17 | 7.85 | 8.36 | 8.61 |
| 75° | 6.39 | 8.00 | 8.66 | 9.14 |
| 90° | 6.57 | 8.24 | 8.89 | 9.67 |
| 110° | 6.50 | 8.42 | 9.33 | 10.63 |
| 120° | 6.37 | 8.41 | 9.61 | 11.20 |
| 135° | 5.70 | 8.03 | 9.34 | 12.02 |
| 150° | 4.78 | 7.15 | 8.54 | 10.59 |
| Run VMG | 4.14 | 6.19 | 7.43 | 9.17 |
How they are set up
The range each sail spans across the fleet.
Nearly all carry a folding propeller. A bowsprit is standard across the fleet. Crew weight is declared around 680 kg.
Rigging
J/121 rig and sail dimensions
A J/121 carries 15.24 m of mainsail hoist on a 5.07 m boom, a forestay 15.63 m above the deck and a 7.02 m bowsprit. Typical figures across the 11 boats measured under the current VPP, with the range each one spans.
Rig
Sails
The spinnaker spreads widest of all — 149 to 190 m² depending on bowsprit and set-up. Before ordering a sail, read the figure on your own measurement record rather than the typical one for the design.