Mastering the C-Class

New C-Class catamaran champion Fred Eaton talks us through how he managed it

Finally after more than a decade, the world championship crown in the most efficient sailboat class has been prised off Steve Clark and now firmly resides with Canadian Fred Eaton. At the recent C-Class Catamaran Championship (aka the 'Little America's Cup') in Toronto, Eaton, his crew Magnus Clarke and their Alphasolid-wing sail catamaran were unbeaten in both the fleet racing and the match racing by Clark and his equally wizened helmsman Duncan MacLean on the defending champion, Cogito, the boat that has reigned supreme in the class since demolishing Australian Lindsay Cunningham's Yellow Pages The Edge in 1996.

The racing

While the scoreline of 3-0 in the fleet racing and 5-0 in the fleet racing indicates something of a walk-over for the new Canadian champions, in fact the competition was far closer, at least when the wind piped up.

Four C-Class catamarans raced the series out of the Royal Canadian Yacht Club. In addition to Alpha and Cogito were a heavily revamped Patient Lady VI, a veteran of the 1985 event and Eaton's foil-born sistership to Alpha, Off Your Rocker. From the outset in the two days of fleet racing it became apparent that among the four there would be two separate races - the foiler looked good for the camera, but only able to compete with the 22 year old Patient Lady around the race course. In fact there were occasions during the fleet racing when Cogito and Alpha lapped the two slower boats as they sailed three times around a windward-leeward course. This prompted Eaton's team to remove Off Your Rocker's foils prior to the match racing at which time she began to demolish Patient Lady VI.

Racing was held in light, sub-10 knot conditions, one race canned when the wind disappeared altogether, with the exception of the final day when it was gusting up to 20 knots.

Come the match racing between Cogito and Alpha, typically the experienced C-Classers Clark and MacLean won every start, the two boats level-pegged upwind and then Alpha gained the lead on the downwind leg which she then held until the finish. So was this boat speed or local knowledge, Eaton and Clarke holding the advantage of racing on their home waters?

"I think it was boat speed rather than local knowledge in general, once the match racing started certainly," says Eaton. "I think they won every single start in fact! Because we are confident of our speed downwind, particularly in the light air, our goal was to start clean and so they were probably looking to win the start while we were looking to avoid a penalty."

After winning the first race on day one and having the second canned when the wind died, the second day of match racing was made harder for the Canadians when they broke the twist control on their wing and were forced to jury rig it on the first beat. And yet, they managed this and still slipped by the American team. The second race that day proved extremely close too. "On many legs we had the boats come within a couple of boatlengths of each other," recounts Eaton. "It was very much a race for position. I think the boats were very evenly matched. We ended up winning that but we definitely stole a race there we felt."

The final day saw Steve Clark walk into the boat park with more of a spring in his step. With winds gusting up to the mid-20s, perhaps finally Cogito would shine against Alpha in bigger conditions? Eaton and Clarke were less keen to try out their perhaps more fragile equipment in the bigger conditions, the class having a wind limit of 20 knots, yet the race committee were up for holding some races and they were pursuaded to venture out.

"I think by the start of the race, it was about 16-18 maybe with some gusts up to 20," Eaton continues. "Certainly it was full-on, but there was also quite a sea state running. Again they won all the starts. We were content to follow them up the first beat. I was waiting to see who’s rig was going to fall down first!

"In the first race we went around for two and a half laps and there had been a change of course and Steve and Duncan overstood the mark, to our benefit, and I knew where the mark was going to be and we tacked for the mark when I thought we had overstood it - I didn’t want to have to tack again, as both boats were backing out of the occasional tack. So we led them into the mark and at that point we went full speed and if the boat was going to blow up the boat was going to blow up. So we knew that was going to be our opening. And they closed the distance again downwind. We beat them - but only just - we had to finish then or they would have been past us."

In the final race, Clark and MacLean match raced Alpha into 'coffin corner' behind the pin, the Canadians kept pinned out for around a minute and a half after the gun. Cogito was significantly ahead off the line and extended up the beat to round the top mark ahead. "We came back downwind and we closed in and passed them on the first downwind as we rode a gust out to the left," Eaton takes up the story. "We got to the bottom mark comfortably in the lead. Then as we went upwind we also tacked back and we covered the right side where the pressure was and had built a big lead by the top mark which we preserved downwind. But then we ran into trouble upwind and nearly lost it to them and just managed to stay ahead by the top mark and then we had a very close boat race all the way back downwind to the finish."



A decisive result

So 5-0 to Alpha and Fred Eaton's Canadian team and Cogito conclusively beaten for the first time since being launched 11 years ago. For Eaton it was a huge weight off his shoulders. "I really hadn’t expected to win the race. I had hoped very much not to lose every race and be embarrassed, because Cogito has had such a successful career you don’t look good even if you have a credible boat if you lose every race.

"People will jump to conclusions about how badly we beat them because of the scoreline. It really wasn’t that big - it was really much closer. We won three of the five races in the match racing by small amounts and it might not be replicable if we tried again. Two of them I am comfortable we were going to win anyway, but three of them were anyone’s race."

While Alpha was clearly the faster in the lighter conditions, Eaton was particularly pleased with beating the wily Americans in the bigger winds of the final day. "I would have to say the last day was the most impressive, the day I felt best about, because it was not our conditions. We managed to sail our way to the front and not because our boat was faster. It was very even racing and we were forced to go out and sail in conditions which we hadn’t prepared for and which we really didn’t know if we could handle."

Design and technique

Conditions on the final day really did push the potentially fragile C-Class catamarans to their limit, the crews offroading their Ferraris. For this final day Alpha had some new rudders fitted with small T-foils sticking out around 100mm each side, designed, along with her larger bows to reduce pitching. "That seemed to help us quite a bit downwind - the boat gets so scary in waves and wind," continues Eaton. "Certainly Cogito put her bows in several times. We never really put the bows under even though we had green water back to the beams a couple of times with both bows in. But we didn’t feel it was going over the nose when it was clear that the Cogito boys had the waves back to the beam and were going up on their nose."

Typically on Alpha Eaton says they were trying to keep their speed to around 17-18 knots so that when a gust hit they could bear off and prevent their speed exceeding 20. "Also I wanted both hulls on the water just because there was so much pressure on the bows I was worried about trying to fly it with one hull up and sinking the hull. Upwind speed varied between 10-15 knots depending on whether we were pinching or footing." Not bad for a 25ft catamaran...

So why was Alpha so much faster in the light? Most of this was down to weight, reckons Eaton. Their wing was 20lb (9kg) lighter than Cogito's, also lowering their centre of gravity and Eaton and Clarke were around 30lb (13.6kg) lighter than the American crew. "That is an advantage in light airs. It is a disadvantage upwind in heavy air," says Eaton. While these numbers are small, the all-up weight of Alpha, wing and all, was just 350lb (158kg) - the hull weight alone of a 20ft long Tornado for example is 135kg.

While the design of both Alpha's platform and wing was based very closely on that of Cogito it also had some signficant differences which also contributed.

Alpha's bows, as we have mentioned, also had more volume in them and according to Eaton "when you are going upwind or in waves they had the advantage, but downwind we have a nice big bow to ride on and it wasn’t going down as far. I think the bows are more of a trade-off between one or the other, there isn’t that big a difference."

The section of Alpha's wing was around half the thickness of Cogito's and while it was very similar in profile it was also around 2ft taller. "My crew Magnus Clark designed a special aerofoil section so that our wing produced a little more lift and have a little less drag than their wing," says Eaton. "Knowing Cogito’s aerofoil section we tested ours against theirs several times and we looking at it against the Lindsay Cunningham section [on The Edge] as best as we could replicate it. We could see how the Cogito wing was better than Lindsay’s wing in our analysis, and so we just designed against the Cogito wing."

The thinner wing gave the Alpha crew improved peak power and lower drag across the spectrum, but the price for this was a wing that was prone to stall faster than Cogito's. "It was less forgiving, but we learned to sail around that," says Eaton. "Principally it is a downwind issue, when you are sailing at very high angles of attack - when our wing stalls it stalls very quickly over the whole surface, which requires you then to round up 30-40° to reattach the flow, if you can’t do that in the first second or two. I think the Cogito wing probably gives them twice as long before the stall propagates that far. They can probably sail a little more stalled than we do sometimes and they can reattach flow probably faster than we can. So we just had to make sure we never stalled it downwind."

Typically they were tacking through 90°, although they would pinch up to 40° and foot down to 50° off the wind. Eaton reckons Cogito was able to sail a little higher, possibly up to a tacking angle of around 70°. Downwind they could gybe through 90° but more typically around 110°. "In the third race we were gybing through nearly 140° as there was some weird wind sheer stuff going on and it was just terrible trying to get downwind. Nothing worked. At one point we tried just pointing it at the mark and that was worse..."

Compared to sailing 14s or 18ft skiffs that Eaton is more used to, he found there was a whole new tactic to sailing the C-Class too. "One of the significant differences on how we sail these boats is how sensitive we are to finding increased pressure on the race course, because a half a knot of extra pressure can give you an extra knot of boat speed. And therefore that forces you to cover the other boat closely or be very confident if you split that you are heading off to find better breeze. So pressure is paramount and wind shifts really aren’t that dramatic an issue, because effectively half of the wind we are sailing to - because we are going nearly twice the wind speed most of the time - is apparent so it never shifts."

With the apparent wind never much more than 60° off the bow, Eaton reckons wind shifts when sailing the C-Class are about half as important as they are on a high performance like an 18ft skiff and perhaps an eighth as significant on the C-Class as they are a typical cruiser racer monohull.

Both Alpha and Cogito have three element wings with the crucial slots between them to enable flow to be attached over the surface of the wing to a much greater degree than a soft sail - the secret to the massive lift to drag co-efficient of their rigs. The rigs can both induce twist into the leading and trailing elements.

The control lines to operate the complex wing on Alpha are identical to those on Cogito.
"We have four controls on the boat," explains Eaton. "We have a main sheet, we have what we call a 'camber control' which controls the depth of the sail. It works like an outhaul would work down low on a regular sail, but our works all the way up the sail. We have a twist control which basically works like a boom vang would on a regular boat, except that it only controls twist and doesn’t control other things as it does in a sail. That operates on the leading edge that twist control. And there is also a twist controller on the third, back element of the wing, that Steve Clark refers to as 'wash out' in the wing. I’m not sure myself if it is washout or twist, but it is doing a similar thing - it permits the depth of the sail to get smaller as you go up and the upper leech to open out more."

The amount these sail controls work is similar on Alpha despite their finer section wing. "We may have less twist in element one than they have because we have a narrower range at the bottom before our twist control arm hits the outside of the wing," says Eaton. "So they may be able to generate more twist in the wing than us, but we feel we can generate enough twist. But full camber is probably within a degree or two of theirs. Our secondary twist would probably be pretty much the same, although I would suspect that our element three is not as stiff as theirs. It seems like our leech was often more open than theirs. It wasn’t necessary something we want, but it was that way."



Engineering

There is a story dating back to the early years of C-Class catamarans of venerable designer Rod Macalpine-Downie watching with some satisfaction as one of Reg White's C-Class cats was sailing along and suddenly exploded into a million pieces. When asked why he looked so happy he replied that it was because everything had broken at the same time - an example of engineering tolerances being taken to the limit.

Alpha is also very close to the edge in terms of her engineering, hence why Eaton and his crew were a little aprehensive when inticed to take Alpha out in 20 knot conditions. "We were breaking lines and stuff through chafe, that if we had to sail a series in more breeze, I’d like to make that more reliable. One of the greatest and most impressive things about the Cogito program is how reliable their boat is. And they never give anything away with that and we very nearly did. When we came in at the end of the third day, we had broken a trampoline line and we cracked a daggerboard open - I think we hit a fish so the whole leading edge had exploded - and we had the top of element three about to peel off the mast. We got home just in time!"

So engineered perfectly? "Yes, we engineered it perfectly, but perfectly was way too close! If we’d had to sail the next day - you don’t know what is coming up. If we could add 2-3lbs of carbon fibre to that boat now that we’ve tested it pretty well, it could be a boat with the same kind of reliability as Cogito and that would be a great relief mentally when you go out on the race course, knowing that your boat can hold together and that you’ll be out there until the end."

And some of the reliability issues were not only occurring in the heavier conditions on Alpha. "The way we attach the trampoline to the deck is a place we could definity improve the boat. We had some fancy attachment points we put together and it turns out they chafe through the lines, and if you cut them off and spent another 0.5lb putting on more standard attachment points we wouldn’t have that problem again. So in two races we nearly lost the trampoline, that didn’t really slow us down, but you don’t need it happening it. A little piece of carbon tape at the top of our third element, would prevent that from falling off the boat. The wing clearly withstood a big test and we are pretty pleased with that, but just bearly..."



The foiler

One of the surprises of Eaton's two boat C-Class campaign, he says is just how disappointing the performance of the foiler was. "When we started the program we decided that the guys really hadn’t been very clever and all it was going to take was a Moth-style hydrofoil program to teach everyone how to sail and I was amazed how far off the mark that was. Our genius experiment was like Wily Coyote, it wasn’t so smooth. That’s part of the fun of the boats - it has been a really fascinating and interesting effort. We have learned a lot about boats."

Off Your Rock was identical to Alpha except that it had less beam to accept the two sets of Moth foils within the maximum beam limitation of the C-Class rule. When these were taken off prior to the match racing the boat's performance was suddenly elevated to a level almost comparible with Alpha. "I think our foiler, as we conceived it, has major problems," admits Eaton. "I don’t think it can possibly get as fast as it needs to get to beat a displacement boat in its current configuration."

While they could spend ages working on the foiler concept it is hard to see how they will be tempted by this compared to leaving the foils back in the boat park, elongating the beams and immediately having an Alpha 2. "That would allow us to learn how to sail the boat pretty nicely," says Eaton.

According to Eaton no one came up with any suggestions as to a new concept of foil that might work. We put forward the idea of curved, retractible foils like the OMRA 60 tris have. However this is what Patient Lady currently has fitted. "They are times when they are very successful and there are times when they are not that great," says Eaton of these. "We probably improved Patient Lady’s top speed and it may be that she now has the best top speed of any boat in the fleet on a reach, but it can’t go upwind fast enough and it certainly can’t go downwind anything like fast enough, so what is the right trade off? It is very hard to know."

They have also done a considerable amount of jigging around with Off Your Rocker to try and make her faster. "I think it is fair to say that the four foils in the water plan is going to run into problems going upwind a lot because of the inability to add sail power to it. We had a lot of suggestions like control the flap on the weather foil use it to create suction and more righting moment. Of course we tried that, but as you do that you add more weight to the hull that is in the water and our foils weren’t sized to control that so it just drove the leeward hull back in the water. So we didn’t have the ability to carry enough sail power in essence because the windward foil was lifting the weight of the crew out of the water so it was negating that. The only way to fly the boat upwind was to twist the sail plan completely open and use a third of the available sail power and that’s not good enough against these displacement boats."

According to Eaton they even tried Off Your Rocker as a 'tripod' with the weather daggerboard/foil removed. "It seems to go pretty well and it seems to be the best mode for it upwind at least, but you couldn’t do much with it downwind."

While there is the obvious problem of having four very draggy foils in the water in light wind when the boat isn't flying, Off Your Rocker was also slower when she was out of the water. "Part of the problem with the foils is that you have to choose your take-off speed. If you take off too early then you have huge foils that you are dragging around and when you are going fast you need a very good control system so that you don’t come out of the water. We picked a take off speed of 8 knots and found worked best at 10 knots. The guys sailing the boat say they were fastest on three downwind legs, but they were never with us so they could have been sailing a puff downwind. Even just in a downwind race I would never have selected the hydrofoil over the regular boat. With another year or two of work I believe our hydrofoil boat probably could be faster downwind in normal conditions than Cogito or Alpha, but they are half a leg behind at the weather mark. And there is no amount of ‘a little bit faster’ that is going to save you."



From here

So the Little America's Cup (to give it the name it is no-longer allowed to be called) has a new Canadian defender but unlike Alinghi is taking a more democratic view about where and when the next event will be held.

The good news is that one of the most likely scenarios is that the event may well return to UK shores in 2009, for the first time in 40 years! And this is partly because there could be at least two British C-Class campaigns in the offing. Norman Wijker's Bristol-based Invictus Challenge have hopeful learned their lessons from Newport three years ago and are busy building a new boat while dinghy veteran Roger Angel and designer Clive Everest were in Toronto also looking at the possibility of mounting a campaign.

"If boats can be built we are happy to travel," says Eaton, who confirms that coming to the UK is the most likely scenario. "If some British boats get built, then Steve and I will come over and we’ll race over there. But nothing has been set yet."

In addition to this there is an Australian campaign still bubbling away down under and surely if the event comes to this side of the Atlantic more European teams will emerge from the woodwork. Hopefully if the North Americans come over it will be for more than just one event.

"It would be nice to run it over a longer time period than we did," says Eaton of how they might evolve the racing. "We are trying to be very sensitive to peoples’ work schedules but it left us being vulnerable to having only one condition for the match racing. We were lucky we had two, but it was near run thing. It would be nice to test across a range of conditions."

In the meantime there is bullish talk from Eaton and Clark about packing up their boats and taking them to some regular regattas next year. The Bol d'Or seems a likely candidate although Eaton worries about the strong gusts. And the competition - the Decision 35s and M2s? "Upwind we’d be fine against them. Downwind they would kill us with the extra sail area they can add. If you could pin it at 8 knots of breeze I’d be very comfortable. 300sqft of sail area - that is smaller than an International 14 spinnaker..."