Sonar
Sonar (UK) Ltd · Bruce Kirby · 1979
Updated
The Sonar is a 7.14 m semi-displacement racing yacht designed by Bruce Kirby and built by Sonar (UK) Ltd, first launched in 1979. It races in Sportboat.
Length
7.14 m
23′ 5″
Beam
2.38 m
Draft
1.19 m
Displacement
0.9 t
Sail area
27 m²
On the podium
Where a Sonar 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 Sonar 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 Sonar 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
4.17
42°
Beam reach
7.59
90°
Broad reach
8.86
135°
Downwind VMG
7.00
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.
The stronger it blows, the better this design looks. 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 outruns what it looks like on paper, 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
It falls short on the beat once it pipes up, giving away time it never gets back. That is a hull that will lift and run given enough breeze.
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 beam reach.
How fast is a Sonar
Boat speed in knots, by true wind angle and wind strength.
| Angle | 6 kn | 10 kn | 14 kn | 20 kn |
|---|---|---|---|---|
| Beat VMG | 2.77 | 3.79 | 4.22 | 4.17 |
| 52° | 4.28 | 5.55 | 6.00 | 6.12 |
| 60° | 4.54 | 5.72 | 6.21 | 6.43 |
| 75° | 4.71 | 5.86 | 6.46 | 6.96 |
| 90° | 4.86 | 6.13 | 6.65 | 7.59 |
| 110° | 4.88 | 6.20 | 7.14 | 8.34 |
| 120° | 4.70 | 6.09 | 7.07 | 9.23 |
| 135° | 4.21 | 5.81 | 6.71 | 8.86 |
| 150° | 3.55 | 5.34 | 6.32 | 7.94 |
| Run VMG | 3.08 | 4.69 | 5.81 | 7.00 |
How they are set up
The range each sail spans across the fleet.
Most run a fixed propeller. Crew weight is declared around 310 kg.
Rigging
Sonar rig and sail dimensions
A Sonar carries 8.41 m of mainsail hoist on a 3.44 m boom, a forestay 7.33 m above the deck. Typical figures across the 2 boats measured under the current VPP, with the range each one spans.
Rig
Sails
The spinnaker spreads widest of all — 29 to 32 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.