Viper 640
Rondar Raceboats · Brian Bennett · 1996
Updated
The Viper 640 is a 6.47 m planing racing yacht designed by Brian Bennett and built by Rondar Raceboats, first launched in 1996. It races in Sportboat.
Length
6.47 m
21′ 3″
Beam
2.42 m
Draft
1.40 m
Displacement
0.3 t
Sail area
24 m²
On the podium
Where a Viper 640 finishes when she goes racing.
On the podium
0%
of 10 starts by 1 boat
Wins
0%
Read from 10 starts by 1 boat between 2022 and 2024, counting races with six boats or more.
Recent regattas
The latest events where a Viper 640 was on the start line, named as the organisers publish them.
Campionato Italiano Minialtura2024- Sportboat European Championship2022
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: 9 races of 10 NM or less carry a published distance.
Offshore & coastal
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Not enough data yet: 1 race over 10 NM carry a published distance.
Who she races against
The designs a Viper 640 actually lines up with, most often first. The bar shows how those meetings ended.
Some of the boats it races against
How the Viper 640 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
4.50
40°
Beam reach
9.92
90°
Broad reach
13.20
135°
Downwind VMG
12.06
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.
It needs pressure to show what it can do. 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 the run in a strong breeze, where it goes better than its measurements say it should, and by a margin worth having. It holds that advantage cracked off as well, so the gain is not down to one leg of the course.
Where it pays
It falls short on the beat when it blows, giving away time it never gets back. That is a hull that wants to get up and go, and needs pressure to do it.
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 4.2 kn either way.
At 10 knots this design makes back more than its rating asks on the broad reach.
How fast is a Viper 640
Boat speed in knots, by true wind angle and wind strength.
| Angle | 6 kn | 10 kn | 14 kn | 20 kn |
|---|---|---|---|---|
| Beat VMG | 3.57 | 4.36 | 4.49 | 4.50 |
| 52° | 5.36 | 6.30 | 6.62 | 6.80 |
| 60° | 5.59 | 6.66 | 7.10 | 7.43 |
| 75° | 5.78 | 7.25 | 8.00 | 8.67 |
| 90° | 5.72 | 7.55 | 8.88 | 9.92 |
| 110° | 5.88 | 7.69 | 9.24 | 11.42 |
| 120° | 5.84 | 8.08 | 9.69 | 12.03 |
| 135° | 5.37 | 7.79 | 10.50 | 13.20 |
| 150° | 4.53 | 6.60 | 9.46 | 13.83 |
| Run VMG | 3.92 | 5.72 | 8.20 | 12.06 |
How they are set up
The range each sail spans across the fleet.
Most run a fixed propeller. A bowsprit is standard across the fleet. Crew weight is declared around 270 kg.
Rigging
Viper 640 rig and sail dimensions
A Viper 640 carries 7.83 m of mainsail hoist on a 2.95 m boom, a forestay 7.05 m above the deck and a 4.20 m bowsprit. Typical figures across the 3 boats measured under the current VPP, with the range each one spans.
Rig
Sails
The spinnaker spreads widest of all — 38 to 44 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.