A-Class gets foiling

Mischa Heemskerk tells us about his lift off moment and lessons learned from the Worlds

The A-Class Catamaran Worlds took place recently in Takapuna, New Zealand, and were comprehensively dominated by Emirates Team New Zealand crews, with AC72 wing trimmer Glenn Ashby securing his unprecedented eighth A-Cat World title. But were we the only ones surprised to see the A-Cats foiling?

Previously we had been led to believe that the venerable class for singlehanded dinghy cats had been trying to prohibit such new fangled development. In fact parts of the A-Class rule specifically aim to prevent foiling. For just this very reason, the rule stipulates that no part of a board can be within 0.75m of the centreline (bear in mind the overall beam of an A-Cat is just 2.3m) and boards also cannot be fitted from beneath the hull, ie they must all be top loaded, thereby outlawing T-foil or L-shaped boards with any significant horizontal component.

Nonetheless, as was the case with the AC72 rule, where there is a will, there is a way. While Mischa Heemskerk was in Hyeres last year doing some training, he inadvertently found his DNA A-Cat flying after she’d been fitted some new ‘J-boards’.

“We got a little bit more area and all of a sudden the boat was flying and it was like ‘hey, that’s great’,” the Dutch cat legend recalls. “Then after that we learned what to do better and now the boats are properly foiling.”

While this was the ‘eureka moment’, strangely getting airborne didn’t come with the immediate hike in performance you’d perhaps expect. Perhaps it was due to the increased drag from the catamaran’s two hulls than compared to the set-up of for example, a Moth, but Heemskerk says that in their earliest trials they found they were going at pretty much the same speed as the standard non-foiling DNA cat: “At that stage I could fly the boat - I was up in the air, next to a normal boat going through the water - but I wasn’t making any gains. Then we played around with the toe-in angle and the settings of the winglets and once we got that all right, all of a sudden we took off and we could gain a lot out of it. In fact we gained 400m on one downwind...”

Compared to the C-shaped boards that have been popular in recent years in the A-Class (similar to the ones fitted to the Nacra 17) foils that have a regular lateral curve to them, the new J-foils have a sharper radiused curvature at their bottom (hence their name). In addition, right at their tip they have a little hook, similar to, but much small than, the version that used to be fitted at the end of ORMA 60 trimaran’s lifting boards.

“The hook at the end makes the tip more efficient as a little endplate," explains Heemskerk. "Plus it keeps you tracking. Once the boat starts flying that is taking over the side loads, and it keeps you in the water, whereas with the C-boards you blow out of the water - it does a side slip and you get into an uncontrolled situation.”

In addition Heemskerk says that they have found that they perform better and the boat’s flying ability is improved, if the boards are slightly flexible, bending marginally while under load.

It is interesting to see that thanks to the constraints of the A-Class rule, the evolution of their lifting foils has taken a different path to those of say the C-Class (and in turn the Phantom F18 and GC32...) where the AC72-related L-configuration boards were all the rage in Falmouth last year (where Heemskerk was one of the helmsmen for the Swiss Hydros Lombard Odier team).

However according Heemskerk, the different evolution path of the A-Cat foils is not just down to the rule, but down to the boat – the 25ft long C-Class doublehanded is bigger and heavier than to the featherweight 18ft long A-Cat singlehander, where often the crew is heavier than the boat. Heemskerk believes that even if it were permissible to fit a C-Class style L-configuration board to an A-Cat, the J-boards would still be more efficient. “I think it is going to be tough to make an L-foil, even one that plugs in from the bottom, to be more efficient from this.”

However despite Heemskerk being the first man to successfully foil an A-Class cat and being the defending A-Class World Champion, following his victory in Islamorada, Florida in 2012 (admittedly a year when Ashby was tied up with his ETNZ Cup commitments), it was still Emirates Team New Zealand sailors who managed to show up the rest of the community in Takapuna. There Heemskerk only managed 12th. Was he disappointed? “It was a good result for the amount of time I sailed,” he says.

Not ones to sit on their nether regions, the Emirates Team New Zealand sailors have clearly been busy as they, along with the rest of the Cup community, await publication of the Deed of Gift for the 35th America’s Cup – due at the end of this month/early April we understand. While Glenn Ashby is the class’ leading sailmaker, as a team they appear to have been up to their armpits in A-Class foil development, both using the J-boards and all manner of rudder configurations, including rudders of different lengths. “Because these boards have a natural ride height, they put on rudders that were longer and they matched the rudder to the ride height. That was their secret which we had to catch on to,” advises Heemskerk.

)

The Kiwi rudders typically were around 10cm longer than the standard DNA ones and significantly also had their winglets at the bottom, rather than higher up. Heemskerk explains: “While our winglets were 50cm under the boat, theirs were 70cm under and they had L-shapes and T-shapes – in fact, they had a whole armoury of rudders which they tested and they had five boats going around... And they had a shed there. But we were very happy that they were using our boats (DNAs) because they did great development for us over there...”

The Kiwi armoury also included rudders where the rake of the entire rudder could be changed while sailing via a twist-grip at the end of the tiller (like the typical Moth/International 14 set-up). Heemskerk maintains that while this was perhaps overkill for an A-Cat, it was nonetheless extremely useful to determining what the optimum rake for the rudder and its winglets were. “They found what the right setting is and once they found that – that is what they used: It is roughly half a degree angle of attack on the winglet.”

Since the Worlds, much of the ETNZ development work carried out on the DNAs is in the process of filtering into production, in particular with the Dutch multihull manufacturer's latest appendage packages.

“We learned a lot,” Heemskerk admits. “It was super to be out there and learn the latest things and now it is about putting it back into the new DNA and making it available for everybody so that they can come and foil with us.”

In terms of practicalities, typically foiling downwind is at present happening in eight knots of wind or more. However foiling upwind or through manoeuvres remains something of a 'work in progress'. “I have flown a few times upwind, but we’ve had no time to practice it yet,” Heemskerk admits. “When we’ve got a few more guys, we’ll go and practice foiling upwind. When I’ve done it, I’ve had to come down two degrees, when you ease the mainsheet, but the hardest thing I found was - once you’d popped out of the water - was to pull the mainsheet back in because the boat accelerated so hard. All of a sudden it went from 14 to 18 knots of speed. But within a minute of flying I had gained 300m on the guy I was training against, so that clearly has a lot of potential...”

On that occasion there was around 18 knots of wind and there was flat water thanks to the offshore breeze, but Heemskerk reckons that at the moment you need probably more than 16 knots of wind to get foiling upwind.

In terms of controls for the boards, there is obviously up/down, however their rake can also be changed, determining the amount of lift the board generates. This is set, Heemskerk says, depending on the conditions and in particular the sea state.

While over the years we’ve publish countless articles about how to go foiling in Moth, it is interesting to compare this with the A-Cats. According to Heemskerk, the technique is distinctly not like that of foiling a Moth. With the A-Cat, the aim is to try and keep the platform as level as possible at all times.

“We are trying to keep it flat, because effectively when the J-boards are in the water it creates a V-shape, so flat is good,” says Heemskerk. “The boat wants to naturally come flat, because of the way the boards are set up now it creates a dihedral - the whole thing is designed to go through the water level. That’s great because then you don’t have the side force of the sails so much leaning on one hull, so it flies easier and there is less aero-drag because the trampoline and everything is going straight through the air.

“Basically you trim the ride height with the sheet tension - a bit more side force, you sheet in and it pushes the hull down.”

A side effect of the new boards providing so much lift is also that they give the boat much improved pitch stability. “That is the cool thing,” says Heemskerk. “In Takapuna I sailed out to the race track next to a boat with straight boards, one of the older style. In 18 knots of breeze he just got blown over, straight over the nose [and I didn't]. And there was one race when I sailed out of the back of a wave and the boat fell into the water and I fell forward – I was up by the forestay, but as I climbed back on the boat, it just kept going - it didn’t pitchpole or anything. And I went on to win the race! So as the stability of the boats now is so much better, it makes them easier to sail.”

Heemskerk is continuing with his work on the DNA A-Cat this year. He is also still part of the Hydros Lombard Odier C-Class team which is making developments to its package prior to the Swiss team hosting the next International C-Class Championships on Lake Geneva in 2015. He is also helping to coach the strong Dutch Nacra 17 Olympic teams – now down to two boats.

Meanwhile in Europe, the A-Class is preparing for its next major event – the Europeans, taking place out of the Cercle de Voile de Bordeaux Maubuisson in France over 21-28 June – as sailors and manufacturers generally trying to figure out how to adopt foiling. In fact it is a delightful facsimile of what the Moth class was going through more than a decade ago...

It was recently voted that articles 8.1 and 8.2 of the A-Class rule, which are at present trying to limit the ability of the boats to foil, are to stay in, despite the fact that that the foiling genie is now well and truly out of the bottle and these rules only serve to make going foiling more expensive (as was the case with the AC72s...)

Several new manufacturers are coming on to the scene. While some of the top new boats incorporating the latest foil technology will not get you much change from £25,000, several new models are cheaper such as the Polish-built Exploder (not the most promising-sounding name...) which both Nathan Outteridge and Class Pres Andrew Landenberger sailed at the Worlds.

New hardware continues to come out. In France there is the Sam Manuard-designed Addiction, which also appears to have T-foil rudders and hooks on its main foils.  In the UK, where Rutland continues to be the A-Class nerve centre with up to 14 boats based there, Colchester-based Tornado builder and sailor Graham Eeles has a new boat in build, due for launch this summer.

)