J/100
J BOATS · Rod Johnstone · 2005
Updated
The J/100 is a 10.06 m semi-displacement racing yacht designed by Rod Johnstone and built by J BOATS, first launched in 2005. It races in Class C. Across the measured fleet it goes better than its own numbers promise, ahead of 88% of the designs it races against.
Goes better than its own measurements promise, and does it better than 88% of the boats it races against.
20th of 159 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 heavy air.
Length
10.06 m
33′ 0″
Beam
2.81 m
Draft
1.76 m
Displacement
3.2 t
Sail area
50 m²
On the podium
Where a J/100 finishes when she goes racing.
Not enough data yet to show how this design finishes. It has not been found in the race results we have collected so far.
Recent regattas
The latest events where a J/100 was on the start line, named as the organisers publish them.
No regattas found yet.
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
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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: no races over 10 NM carry a published distance.
Who she races against
The designs a J/100 actually lines up with, most often first. The bar shows how those meetings ended.
Not enough data yet to say who this design races against. No result we have collected puts it on the water beside another design we track.
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
5.29
38°
Beam reach
8.52
90°
Broad reach
10.76
135°
Downwind VMG
8.21
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 off the wind in a strong breeze, where it does more than its size and sail area promise, and by a margin worth having. It holds that advantage downwind 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 1.4 kn either way.
At 10 knots this design makes back more than its rating asks on the broad reach.
How fast is a J/100
Boat speed in knots, by true wind angle and wind strength.
| Angle | 6 kn | 10 kn | 14 kn | 20 kn |
|---|---|---|---|---|
| Beat VMG | 3.38 | 4.70 | 5.14 | 5.29 |
| 52° | 5.19 | 6.76 | 7.19 | 7.36 |
| 60° | 5.48 | 6.95 | 7.40 | 7.61 |
| 75° | 5.68 | 7.12 | 7.66 | 8.05 |
| 90° | 5.78 | 7.24 | 7.80 | 8.52 |
| 110° | 5.92 | 7.58 | 8.34 | 9.22 |
| 120° | 5.79 | 7.54 | 8.59 | 9.92 |
| 135° | 5.16 | 7.21 | 8.35 | 10.76 |
| 150° | 4.33 | 6.49 | 7.65 | 9.44 |
| Run VMG | 3.75 | 5.62 | 6.70 | 8.21 |
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 590 kg.
Rigging
J/100 rig and sail dimensions
A J/100 carries 11.58 m of mainsail hoist on a 4.11 m boom, a forestay 11.68 m above the deck and a 4.87 m bowsprit. Typical figures across the 13 boats measured under the current VPP, with the range each one spans.
Rig
Sails
The spinnaker spreads widest of all — 71 to 102 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.