Daily Archives: September 24, 2012

The Mesh Shop VO-70, part II: Racing

Mesh Shop VO-70

I recently posted about the Mesh Shop VO-70. Inspired by the Volvo Ocean Racer, the VO-70 is a beautifully designed and carefully constructed craft that earns high marks for it’s style, the accuracy of it’s mesh build, and it’s durable BWind 2.5 sail engine. It’s a great boat to cruise across the grid at high speed.

I suspect many sailors who get this boat will want to race it, so I wanted to add a few additional comments about VO-70’s racing features.

A Fresh Breeze

The VO-70 does not use the standard raceline WWC windsetter; instead it introduces a new race wind system, based on Becca Moulliez‘s BWind 2.5. The boat comes with a separate “iPad Contoller” that a skipper or race director can wear to set race wind.

click to enlarge

The iPad has six options for wind speed and eight wind directions to choose from. When a skipper or race director hit’s ‘enter,’ the wind settings are broadcast to all nearby boats that are listening and in-range. The broadcast continues for a few minutes, then automatically turns off.

Other skippers who want to join the race type “racing” in open chat to let their boats listen for the wind. Once a boat gets the racewind message, it locks the new parameters and won’t allow any changes until the skipper says ‘cruising‘ and leaves race mode.

The iPad interface is a great idea and it works well; it’s both easy and intuitive to use. My only suggestion would be to make the iPad transferable, so any RD could use it to start VO-70 races. I’d suspect sharing it will become more important as new boats get added to the list using the new system. It’s a small step toward establishing a legitimate, alternate race wind interface.

Wind Variance

OK, let’s talk about Race Wind Variance. VO-70 handles it differently, and I promise this will only take a minute, and there will be no math! 🙂

The wind that drives a sailboat is often fickle, and adapting to wind changes is an important part of race strategy in both RL and SL. The standard WWC race wind script includes settings for wind variation. A race director can adjust the magnitude and nature of both wind gusts and directional shifts.

In early 2008, Vin Mariani wrote two fantastic articles detailing how wind variance works in SL races (Blow and Second Wind). He focused on Kanker Greenacre’s original “Tako wind,” but the same basic principles apply to Mothgirl Dibou’s WWC setter too. As shown in the figure above-right, the racewind from these setters gradually shifts wind direction in incremental steps to one side then the other, over a few minute interval. A good skipper can watch the wind shift and adjust the sails in response; a great skipper can even try to anticipate when shifts will occur.

I’m bringing this up here because the VO-70 uses a different system.  VO-70’s  iPad controller allows a race director to adjust the amplitude of wind gusts and directional shifts using an integer scale from 0 to 9. However, the frequency of the wind change is much faster than what you get with a WWC, and the two systems are not equivalent.

Here’s an example of what I mean. The blue line on the chart to the right plots the real wind angle for a VO-70 each second for a total of eighty seconds, with the wind variance set to “5” on the iPad. As you can see, the curve is an irregular sawtooth pattern, with wind direction swinging back and forth around the mean every other second. To emphasize the difference, I’ve superimposed the directional shift from a WWC (green curve) and Kanker’s windsetter (red curve) over the same timeframe. The WWC causes a gradual shift in wind direction, while the BWind 2.5 windsetter generates a sequence of quick wind shifts that leaves the underlying, average wind angle unchanged.

Kain Xenobuilder and Becca Moulliez are aware of this difference, but they point out that the wind pressing against a sail (or any object) is constantly changing at a rapid rate. The VO-70 wind variation models this second-to-second wind jitter, not the gradual shifts a WWC produces.

Becky mentioned that longer-term WWC-type variances may be included in future updates to the new wind system. Dutch suggested that racers should focus on the HUD readout for apparent wind, and sheet accordingly. That makes sense to me too, since the HUD’s AWA index reacts more slowly, and represents the wind angle and speed that actually drives the boat.

If this sounds confusing, here’s the bottom line: VO-70 has a new race wind system, it’s different than what most sailors are used to, and it’s worth trying it out. SL Sailing can’t advance unless we all encourage new systems made by thoughtful, dedicated people. 🙂


Although the VO-70 does not use the WWC setter, it is fully compatible with the common race lines in SL. In fact, once a skipper enters race mode the boat automatically gives itself a random race number. 🙂 That should prevent the problem racers forgetting to correctly ID their boats!

The VO-70 has an additional nice feature in that regard: If a boat crashes during a long race, when it gets returned to inventory it reliably remembers the race wind and race ID number. A skipper can therefore just re-rez that boat at a convenient spot, and get back in the race again! 🙂

Phantom Factors

The VO-70’s dimensions and sailing performance nicely match the the RL Volvo Ocean Racer. However, unlike the RL boat, many components of VO-70 are phantom, including  the spars, rigging, sails, bowsprint and keel. That can be an advantage for both the skippers and race directors, reducing the risk for collisions at the raceline or along the course. At the same time, it complicates race planning since an RD needs to set special regatta rules that cover phantom  collisions. This is usually no big deal, and can be as simple as: “If it’s phantom, it can’t hit you.” 🙂

Wish List

The large size, solid build, and low-overhead scripting of VO-70 make it a particularly good candidate for long-distance races, so the issue of phantom race course collisions should not amount to very much.

In my hands the boat is pretty rugged, and it can usually make it across 100+ sim borders at high speed without much trouble, even on those ‘bad grid‘ days. 🙂

Good boat, Mesh Shop!

I have to admit I’m greedy though, and since Christmas is not that far away, there are two things I’d love to have on a future VO-70 racing update. They are:

1. WWC compatibility. Since VO-70 uses it’s own wind system, right now it can’t join mixed-class races in SL without first making special arrangements with the Race Director. Having an option to switch between BWind 2.5 and the generic WWC wind would greatly increase the number of racing opportunities for this boat, and give owners a chance to ‘show it off’ to their friends.

2. Windshadow. Windshadow is a powerful tactical weapon in sail racing. With experienced skippers at the helm, windshadow turns a fleet race into an intricate chess match. Windshadow is currently built into the WWC system, so adding it to VO-70 would not be difficult. Both the Ktaba Teleri and Melges-24 are dual wind-system boats that use that solution for their shadow. 🙂

These are small points for a Big Boat however, and as I said I’m just greedy. I want to sail this boat everyplace!