AC45 v Extreme 40

Terry Hutchinson and Dean Barker share their thoughts

Friday November 18th 2011, Author: James Boyd, Location: none selected

Emirates Team New Zealand skipper and helmsman Dean Barker and his Artemis Racing counterpart, Terry Hutchinson (who was in Barker’s afterguard for the 32nd America’s Cup) have both been sailing on the America’s Cup World Series and Extreme Sailing Series this season and in this article offer their views between the AC45 and the Extreme 40, the two grand prix inshore catamarans of the moment.

While the Yves Loday-designed Extreme 40 was first launched back in 2005, the AC45 has the advantage of being brand new this season and obviously is fundamentally different with a wingsail instead of a conventional mainsail. As is the trend in offshore multihull design, so the AC45 is be longer than the Extreme 40, with added volume in her bows, but it is a fraction narrower. The 40 has less sail area and weighs less, as you would expect.

  AC45 Extreme 40
LOA  13.45m 12.19m
Beam 6.90m 7.01m
Displacement 1400kg 1250kg
Mast height 21.50m 18.90m
Sail area (upwind) 133sqm 100sqm
Sail area (downwind) 210sqm 185sq

However there are less obvious differences. The Extreme 40 has been designed to be ‘easy’ to sail – with for example symmetric daggerboards and a self-tacking jib, whereas the AC45 has been purposefully made difficult to sail, the design brief specifying that it should require athleticism to sail. Which it certainly does.

“The AC45s are way more demanding physically to sail,” states Barker. “The systems are quite challenging for a lot of manoeuvres. You have to deal with runners and the boards up and down, which are the two elements on the 40 you don’t have to deal with, and that in itself utilises different people in different manoeuvres. On the 40 you sail with the boards down pretty much all the time because they are symmetric whereas on these they are asymmetric. So that little gem in itself keeps everyone pretty tied up.”

Hutchinson agrees, pointing out that the AC45 is also harder to get around, having to clamber beneath the low wing and over the centreline spine and that runs fore and aft to counter rig loads. “And it has bigger gear. The Extreme 40 feels like a toy when you whip it around.”

However the wing itself is simpler to operate, compared to the Extreme 40 mainsail, as Barker says: “You have got three controls, two of them are pretty static and the third is the wing sheet which is a combination of traveller and mainsheet on a 40. So in that respect when you are set up and going it is a lot less work, although Glenn [Ashby] is getting a pretty good work out on the wing winch most of the time!”

Barker adds that with the AC45s there is more emphasis on fine tuning the boat and keeping them sailing well and they seem slightly more tweaky than the Extreme 40s. But a significant difference thanks largely to the AC45’s more modern hull shape and narrower beam is that they are better through manoeuvres.

“The boats tend to sit up on top of the water a lot more so tacking and gybing you can steer around a lot more without feeling like you are washing off too much speed, so in that respect they are a lot more forgiving to sail.”

In theory the longer bows should make the AC45 less prone to pitchpoling, although as Russell Coutts demonstrated training in San Francisco earlier in the year, this is quite possible.

As a one design, the only area of variation between the AC45s is in their headsails and downwind sails, although Terry Hutchinson says much can be done with the set-up of the wing too. “Within the wing there are all the lines you can adjust to control the twist of the wing, so there is quite a large amount of variation that you can affect the wing shape.”

Between the two boats, when he is helming Hutchinson says that he focuses on different things. “On the Extreme 40, it is easier for me to look at the mainsail and tell what is right or wrong. It is not as easy for me to look at the wing and I spend very little time looking at the wing because a) it requires a lot of concentration to drive the boat well and b) to look at it and really understand everything we are talking about, I would be better served to have someone else steer the boat for five minutes.” This is simply due to unfamiliarity. “Soft sails you can look up and say ‘that doesn’t look right’ or ‘we need more Cunningham or more twist for the same amount of sheet tension’ because you’ve spent the last 25 years of your life looking at it. With the wing it is not so noticeable.”

One of the most noticeable differences between the wing and the softsail is that the flow over the wing remains more readily attached. As Hutchinson puts it, if you get slightly out of balance going downwind with the wing, you are still going 18-19 knots, whereas if this happens with the softsail, boat speed can drop by 4-5 knots.

But the most noticeable advantage of the wing as opposed to the softsail comes in big conditions. As Hutchinson explains: “When it is windy, with a soft sail you ease the sail out and the sail gets deeper and it actually powers the boat up, plus the Extreme 40 lacks a little volume in the front of it which is why it goes bow down quickly. But if you want to depower the Extreme 40 you want to sheet the main on and ease the traveller out, which is counter-intuitive – you go around the top mark with a big hull fly you think ‘ohh, I need to ease the main’, so you open the [hydraulic] valve and you ease it and that is actually about the worst thing you could do. You should pump the main on and the Cunningham on and drop the traveller and the take your chances! With the wing, when you ease it, it doesn’t grow and power up. Plus you have a way better hull shape that keeps the bow up.”

Also noticeable is how much power the wing generates compared to the softsail on the Extreme 40. As Hutchinson points out: “The nice thing about the AC45 is that if you don’t snap the genniker in out of a gybe, you can still get the windward hull up with the wing, whereas on the Extreme 40 you need the genniker to get the hull out. After a gybe on this the genniker has a 2m grind still and yet the hull is out and you are flying. That is a really nice feature of the AC45.”

Surprisingly, according to Hutchinson there is not much to choose between the pointing ability of the two boats. In fact the same theories apply to both. “If you had your option, you’d overstand, not understand, because pinching and going slow is just painful and doesn’t work.” This strikes us as odd because you would have thought that the higher efficiency of the wing would allow for better pointing. But Hutchinson confirms that the tacking angles of the AC45 and Extreme 40 are similar.

Another oddity is that at present Hutchison believes the Extreme 40 is the faster boat when it comes to ultimate speed, although the wing should in theory out perform the softsail through its higher efficiency in lighter conditions. “I am not a naval architect, but you would think that some of the upper end speed potential of the boat is limited by the fact that the hulls are safer, whereas on the Extreme 40 you are limited by that. But we have gone fastest on the Extreme 40 two sail reaching, not with the genniker and it is the same with the AC45.”

When it comes to the America’s Cup World Series short course formats and in particular their reaching starts both skippers are taken by it, although in the America's Cup World Series fleet races it makes for different tactics from conventional upwind starts.

So where to start? Barker: “You have to balance up where the puff is, whether there is another puff coming, whether you are on the bottom side of a puff – getting that initial slingshot out of the start is just key. If you get rolled by one boat you get spat out of the back pretty quickly. There are definitely opportunities around the course but there are definite advantages to get to the top mark among the top two or three boats.”

Hutchinson also believes in the supreme importance of the starts: “Generally whoever rounds that first mark ahead, it takes a lot to get past them, because the rich get richer. The boats that get tangled up in traffic get tangled up in traffic and the guy in the lead just sails off.”

But he adds that he finds the America's Cup World Series course formats exciting, the analogy of the start to the first reaching mark being the equivalent of heading for the first corner in a Formula 1 Grand Prix. “I think it is awesome. It is a matter who get into the lead while the rest of the guys fight for the scraps. If there is something I am excited by, it is that. And if you magnify that to the AC72, it is going to be horrendously cool!”

However Hutchinson warns that while the America’s Cup World Series is almost a distraction, you can’t lose sight of the end game, which of course is the America’s Cup in 2013 in San Francisco in the substantially larger animals that will be the AC72s.

See Joey Newton's video tour of the AC45 platform here and Dirk de Ridder's assessment of the wing here.
 

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