J/45
J/Boats · Rod Johnstone · 2021
Updated
The J/45 is a 13.84 m semi-displacement racing yacht designed by Rod Johnstone and built by J/Boats, first launched in 2021. It races in Class A. Across the measured fleet it goes better than its own numbers promise, ahead of 58% of the designs it races against.
Goes better than its own measurements promise, and does it better than 58% of the boats it races against.
20th of 46 in its class.
Updated — First Race Edge for this design. Enough boats of this design have now been measured to rank it. It is strongest in medium air.
This design has been found in real race results — 2 starts across 1 event — not only in measurement files.
Length
13.84 m
45′ 5″
Beam
4.25 m
Draft
2.33 m
Displacement
10.8 t
Sail area
120 m²
On the podium
Where a J/45 finishes when she goes racing.
0
Wins
0
Seconds
1
Thirds
2
Starts
Not enough races yet for a percentage — these are the counts so far. We keep collecting results, so this will fill in.
Read from 2 starts by 1 boat between 2026, counting races with six boats or more.
Recent regattas
The latest events where a J/45 was on the start line, named as the organisers publish them.
"Μακης Πανταζης" - Αγκιστρι2026
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: no races of 10 NM or less carry a published distance.
Offshore & coastal
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Not enough data yet: 2 races over 10 NM carry a published distance.
Who she races against
The designs a J/45 actually lines up with, most often first. The bar shows how those meetings ended.
Met too few times for a figure:
Sun Fast 3200 (2 meetings), Moody 39 (2 meetings), X-43 (2 meetings), Bavaria Cruiser 40 S (2 meetings), X-412 (2 meetings)
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
6.16
38°
Beam reach
9.75
90°
Broad reach
11.45
135°
Downwind VMG
8.89
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 design is even-tempered. It rewards preparation and crew work more than it rewards picking the right day.
Where it gains
Its best ground is upwind once it pipes up, where it goes better than its measurements say it should, and by a margin worth having. It holds that advantage on a broad reach 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 0.4 kn either way.
At 10 knots this design makes back more than its rating asks on the broad reach.
How fast is a J/45
Boat speed in knots, by true wind angle and wind strength.
| Angle | 6 kn | 10 kn | 14 kn | 20 kn |
|---|---|---|---|---|
| Beat VMG | 3.92 | 5.45 | 5.94 | 6.16 |
| 52° | 6.04 | 7.91 | 8.39 | 8.61 |
| 60° | 6.41 | 8.14 | 8.63 | 8.87 |
| 75° | 6.66 | 8.31 | 8.91 | 9.33 |
| 90° | 6.53 | 8.40 | 9.02 | 9.75 |
| 110° | 6.72 | 8.70 | 9.46 | 10.49 |
| 120° | 6.59 | 8.68 | 9.69 | 10.86 |
| 135° | 5.88 | 8.32 | 9.43 | 11.45 |
| 150° | 4.92 | 7.39 | 8.78 | 10.27 |
| Run VMG | 4.26 | 6.40 | 7.67 | 8.89 |
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 770 kg.
Rigging
J/45 rig and sail dimensions
A J/45 carries 18.01 m of mainsail hoist on a 6.11 m boom, a forestay 18.53 m above the deck and a 6.27 m bowsprit. Typical figures across the 8 boats measured under the current VPP, with the range each one spans.
Rig
Sails
The spinnaker spreads widest of all — 91 to 223 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.