VO70 Downwind Sails

The Volvo Ocean Race have always been on the cutting edge of downwind sail development, and we’ve seen many innovations trickle down to club racers and cruising boats.

The Code 0 might be one of the best examples. First seen as a “rule cheater” in Whitbread 1997 and now ubiqutous in offshore or shorthanded races. And downwind sail handling is becoming more and more similar on everything from large trimarans and VO70s to smaller cruiser/racers.

We’ve also seen the development from race to race. To get an insider’s view sat down with Henrik Søderlund from North Sails during the stop-over in Lorient. Henrik is sail designer for Team Telefonica,

In an effort to keep costs down, there’s been some serious limitations in the number of sails, both manufactured and carried on board. But with fewer sails it becomes even more important to get the absolute best sails. So many teams spent as much money this time, but on CFD and wind tunnel testing, to be sure to get the best sails possible. Henrik thinks the boats might even be faster around the globe this time, despite having fewer sails in the inventory.

Also see my interviews with Michel Richelsen on CFD and the Wind Tunnel at University of Auckland who helped all the top teams.

A new approach to design
When we get into the sail development programs, it becomes clear that the process have changed since Juan K entered the stage with ABN AMRO. The traditional approach is to design a boat, a rig and late in the process get the sail maker to design the best sails for that particular boat. This has been the norm for many years.

Enter Juan K, who completely changed the rules.

– Let’s start with the engine, the sails that drive the boat. Take the class rules and design the best sails possible within those restrictions. Then I’ll design a boat that takes advantage of the horsepower. This was a completely new way of thinking and let the sail designers work without many of the restrictions they were used to. We all know what happened. More stability, more power and faster boats.

New materials change the game
When I visited North Sails in Minden in 2010 they built the first 3Di sail for Puma Ocean Racing. Then they wanted to see if it worked, and both Puma and Groupama tried to put 1500 hours of sailing on their forst 3Di mains. Now 3Di is the norm. We see a few Cuben sails, and Doyle on Sanya, but otherwise it’s 100% 3Di. It’s quite a breakthrough when everyone moves to a new technology in a big event like this.

First it’s a matter of durability. All sails held together well and breakages were caused by “the human factor”. Also, a small damage seems to be more containable and doesn’t spread as in other material. UV doesn’t seem to be an issue and most sails are painted for commercial reasons, which helps protect them. In earlier races the difference between painted and non-painted sails were huge. When pushed, Henrik thinks that the life span of a 3Di sails might be double that of earlier materials.

– We’ve also been able to extend the range of each sail, especially at the upper end. All sails look great when used in the middle of their desired range, but when you approach the upper limit it’s another thing. So we manage to get a bigger cross over with the next sail, that might save the team a sail change.

Telefonica sail inventory

Managing the cross over’s between different sails (wind speed and angle when it’s better to change to a different sail) is a big thing. Having a narrow cross over in common conditions might mean many sail changes that costs both time and energy.

And here we get into philosophy of the downwind inventory. Is it about being around without any weaknesses or about being super fast in certain conditions? Another delicate balance.

Three teams seems to be all-round; Groupama, Puma and Telefonica have done their homework and are without any weak spots. There might be an advantage for Groupama, as they seems to slip away in TWA 90 and TWS 14-18, knots but otherwise they seem to be able to match each other. Abu Dhabi is geared more towards heavy downwind running, and Camper does well when it’s more upwind.

With limited options it’s important to know you sweet spots and have the guts to stick to them. It’s easy to get bought up in someone else’s game and trying to beat them at their best angles.

An additional benefit when downwind sails are on a furling cables, is that they require less trimming. A free luff sails needs to be trimmed constantly, and collapsing the sail is costly. Now it’s more forgiving and even if the top speed is lower, the average speed over time might be higher.

Inshore all the teams is required to have a traditional free luff A2 that adds actions and look great on TV. “Colorful for the tourists” as some call it. This is left ashore for the offshore legs, even if some teams have thought of bringing it.

Then there’s a FR0, fractional zero in 3Di, typically 260-270 m2, a MH0, mast head zero in 3Di, typically 330 m2. Finally a A2.5 or A3 at maximum size 480 m2. This is either 3Di or Cuben and can be free luff (Abu Dhabi and Sanya). Those sails are combined with spinnaker- and a genoa staysails.

One sail that was used in the last race was the A6 heavy weather runner that now got left out. It was used for 40-50 hours, and now they have to manage with the existing sails.

Many small innovations
The most obvious one was maybe Campers free luff that could be removed with a zipper. This theoretically gives them a “two-sails-in-one” but this hasn’t really proved to be an advantage. At least not from the other teams perspective.

Other ways to get maximum sail area is the high sheeting point (“tower of power”). Or using a batten, or multiple sheets, at the clew. An additional benefit is the possibility to adjust the sheeting angle by moving the sheet.

Sail handling in practice
This all sound great in theory, but it might be different in practice? I spent some time with Martin Krite and Martin Strömberg, running bow and pit on the winning Groupama. Coming straight from the Ericsson campaign they brought a lot of knowledge, and with the winning Ericsson 4 came a lot of sails.

– We might have done hundred sails in the Ericsson campaign, so Groupama got a head start in that department explains Martin Strömberg who was responsible for sails on Ericsson 3. This also meant we didn’t have to make new sails until late in the process, which meant more slots for new racing sails. A clear advantage compared to projects that started from scratch.

Talking to the guys at Groupama, here’s Martin Krite at his office, they have some tricks that might give them an advantage. The sprit and tack allow them to keep the tack of the spinnakers lower than any of the competitors. Also, in the in-port races they use two identical A2 spinnakers, allowing them to re-hoist without packing the old sail. Small things that could make a difference on a tight course.

One important aspect of downwind sailing is handling. All downwind sails are on furlers. Most are the same type we’ve seen on the IMOCA 60 and other shorthanded ocean racers for years. A couple of teams, most notably Abu Dhabi and Sanya have used top down furlers on their biggest runners. They have worked without problems but might be tougher on the sail that is furled hard onto itself.

Attention to detail: Groupama have bigger diameter furlers on the in-port races for faster and easier handling. Going offshore they change to smaller ones to reduce weight and windage.

Most boats have dual tacklines with 2:1 purchase . The smaller “inner tacklines” is used to get the furler out of the way when changing sails.

Many functions are handled with blocks directly to a winch or jammer. They are easily moved for multiple functions. This is both light and simple, and there’s less hydraulics on Groupama compared to Ericsson 4.

The innovative pit on Groupama, with a central winch and lines coming directly from the mast down below.

Halyard locks everywhere. One would think that a standardized model would make it more flexible, but on Groupama each one is different to minimize weight and windage for each function.

Hydraulics for topmast, checkstay, J4 tack, Cunningham and outhaul.

Franck Cammas seems to be obsessed with windage. So when there’s a frame protecting the helmsman, naturally Franck turns it into a wing profile.

The “forestay tower” tricked the rule as J was measured to the pin and not the intersection with the deck.

Finally, it will be very interesting to see how the new Volvo One Design will work. Sail inventory is even more limited: mainsail, masthead code 0, fractional code 0 and an A3 asymmetric spinnaker. Upwind a non-overalapping J1, J4 and a staysail/storm jib. In total seven sails compared to 10 on the VO70. Volvo haven’t decided whether the wardrobe will be fully one design or not (everyone having the exact same sails), but if they wamt to keep costs down it probably is.