Foils are the newest phenomenon on the Vendée Globe race and one that looks as if it is set to change offshore racing.

But why have these experimental ideas appeared here, in the world’s longest and toughest ocean racing, single-handed, rather than around the cans or on short courses? And how did this happen?

First, let’s just note that the IMOCA 60s have always at the leading edge of oceangoing monohull design. It was in this ‘Open 60’ class (actually a box rule) that canting keels and wing masts were employed to gain an edge.

But in the 2016 Vendée Globe teams with new designs have made another leap forward and we have been seeing some of the fastest speeds ever in the 27-year history of this race and some of the largest separations between new boats and older generation yachts.

To see the foils on Hugo Boss take a look at this video, in which Alex Thomson Racing’s managing director, Stewart Hosford explains the principles at work.

A new generation of these foil-equipped yachts, six brand new boats and one refitted older boat, have turbo boosted the speed of this race in power reaching conditions and pushed it to a new level of brute velocity. At times when reaching these foil-sporting boats have two knots or more quicker.

The new boats, all VPLP/Verdier designs, are Banque Populaire VIII (skipper Armel Le Cléac’h), Safran (Morgan Lagravière), Groupe Edmond de Rothschild (Sébastien Josse), Hugo Boss (Alex Thomson), St Michel-Virbac (Jean-Pierre Dick) and No Way Back (Peter Heerema). The older boat retro-fitted with foils is Maître Coq (Jérémie Beyou).

Searching for a magic recipe

Foils were always going to appear in this fleet as an area of rapid development got applied to a partially open rule. But it became virtually a necessity for the latest generation of yacht designs when the IMOCA class decided that the way to cure recurring rig and keel failures would be to create one-design keels and rigs. The class also changed the stability rule, altering the maximum righting moment allowed and reduced the number of ballast tanks permitted, but crucially they grandfathered existing yachts.

The one-design keels of the new boats are robust, as envisaged, and made with forged steel fins. The new one-design rigs are likewise robust and comparatively conservative; the carbon wing masts are heavier than the previous generation. These changes meant new designs inevitably became heavier than their predecessors —heavier rig means heavier bulb means heavier boat.

That sent designers and skippers searching for a magic recipe to boost performance. They found it, or so they believe, in the huge new scythe-shaped foils capable of lifting boats higher in the water and reducing displacement. Although the boats can’t fly as foiling multihulls do, at peak speeds foils can drive the entire hull forward of the keel fin right out of the water.

There is nothing in the rule to prevent the skippers of older boats from adding foils and, with lighter boats, yachts such as Jérémie Beyou’s Maître Coq might have a further advantage.

St Michel-Virbac, Skipper Jean-Pierre Dick

The three semi-foiling IMOCA 60 concepts

They are all slightly different. In essence, there are three concepts at work: one that designers VPLP call the ‘Dali’ foil because of its ostensible similarity to the artist’s moustache; Alex Thompson’s DSS-style foil on Hugo Boss; and another type designed by Nick Holroyd of Team New Zealand used on Jérémie Beyou’s Maître Coq.

The first is a V-shaped foil on which the purpose of the shaft is to hold out an elbow and tip, but the shaft itself is not a key part. On Hugo Boss, the shaft and tip both provide lift, hence Thomson’s board provides, he says, “a two to three times bigger lifting surface.” It is said that Thomson’s foils begin to generate lift at a lower speed and are efficient to a deeper angle downwind than the others.

On Maître Coq the shaft ends in a flat section and has an elbow with a tip that extends vertically.

Every team has been refining these foils. Most have experienced breakages and, after trying out refinements, are on version 2, 3 or even 4. The point is that, for all teams, foils are still very much a learning game.

Alex Thomson came into the Vendée Globe as something of a dark horse, but his boat appears to have the edge over the rest of the foiling pack in downwind conditions. It remains to be seen if a full conclusion can be made since he broke his starboard foil in November, however, as that makes direct comparisons with fellow leader Armel Le Cléac’h’s Banque Populaire difficult.

Credit: Lloyd Images/ AT Racing

Thomson finished in 3rd place in the last Vendée Globe and is a serious contender for a win this time. He believes that semi-foiling boats will have a clear advantage, and his will have the edge among the foilers.

“Everyone is just trying to get the boat to lift and everybody’s works, but the angle where they pay and really make a difference is quite small. The boat needs to be going faster than 14 knots to make lift better than drag. In 15 knots at 90° true, the ‘Dali’ foils would be equal with [Vincent Riou’s non-foiling] PRB, but when the wind increases they really start to make a difference, and in flat water with no ballast it’s a huge difference,” he explains.

“A non-foiling boat will be doing 21 knots in 20 knots of breeze and a foiling boat 26-28. So it’s an enormous difference, though in the open ocean we won’t reach these speeds; maybe it will be 22 knots. We are slightly different in that we don’t need to heel the boat so we’d like to think it would work in a bigger range,” he says.

The pros of foils have been calculated based on historical data that shows only seven per cent of the course is truly upwind, but the extent of any advantage will depend on the average windspeed around the world and how much of the final part of the race from Cape Horn to the finish is upwind. If largely upwind, as the 2000 race was, the handicapped Hugo Boss might lose its advantage

“The foilers are faster between 80 and 120° [TWA] and if the speed is faster than 17 knots, but the first qualification is to perform during transitions and my advantage is that this is a very simple boat that I know very well.”

Extra speed

In the Southern Ocean, the speed makes these boats uncomfortable. Even before the race, Thomson was on record as saying that his boat slightly scares him. “Well,” he elaborates, “it’s just so uncomfortable. The accelerations and the decelerations are unbelievable. Before, I was averaging 20 knots in the old boat, now you are averaging 23, 24 and surfing over 30. It feels very different.

“It’s been suggested to me that I should wear rugby head protection because of the likelihood of banging your head – it’s gonna happen,” he laughs, wryly. “You really have to hold on. It’s very, very, very uncomfortable. There are times when there’s nothing you can do, you can’t boil any water, you’re just eating energy bars and surviving.”