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Opinions about the new Alinghi mega cat from Adrian Thompson, Phil Steggall and Paul Larsen

Following out look at the new Alinghi mega-cat, we have had some correspondence:

From his base in France, Team Philips ' designer Adrian Thompson has been following the developments:

Well done for getting such an interesting exposure of the new Alinghi. Naturally it made some interesting reading for me and the odd shudder - thought I had got over all that by now.

I’m not sure many useful comparisons can be made between T.P. and Alinghi with regard to structure other than they are both big catamarans which are pushing the laws of similitude. When sail area increases by the square law and displacement by the cube, it’s a tough act to cheat similitude to get the right sail area to displacement ratio. Offshore boats recover some of this lost performance by being quicker through the waves, but an inshore boat just has to have grunt.

Their structural team will have been made well aware of the performance limitations of a maxi cat with a ‘full on off shore’ structure, hence they have taken a very different route with their structure by isolating the rig loads within a space frame and stayed latticework. The hulls will simply keep this lot above the water – well perhaps not always, as the air draft in way of the stays looks like it might be optimised for flat water. Getting that windward hull up in a big swell might be essential.

They are very different structural concepts, but both designs may expect to experience high speed hull divergence. This is what nailed us, and is the result of opposing lateral dynamic loads applied to the immersed hulls as they ‘walk’ through big waves. Ours were structured for 70 tonnes lateral load at the bow and it wasn’t enough. It’s an offshore problem which they may not experience during the challenge, but I guess these beasts will need a bit of sea room stretch their filaments.

I’m touched that they have a photo of my old boat on the wall, although I would have preferred a shot of her doing 21knots in 7 knots TWS which was quite good back in those days fully loaded with round the world stores on board.

The very best of luck to all the team - it’s great to see another wacky cat on the block.

Ocean racing legend Phil Steggall, who more ancient readers will remember having sailed the spindly foiler trimaran We (also designed by Adrian Thompson) across the Atlantic still favours three hulls:

The outcome will depend largely on how the boat is rigged (sailplan) and the point of sail on the race course. The tri may be heavier but control over the sailplan and balance of the boat play a large role. We have seen advancements on tris that have made them the fastest and most versatile boats in the world. What could Alinghi do to disprove this? My money is on the tri....although I really could care less about AC at this point.

So what do people think? Will Alinghi's cat kick BMW Oracle Racing butt or vica versa? Is this the ultimate cat versus tri showdown? Is what we have seen offshore with multihulls at all relevant? What other developments are we likely to see on both boats? Are Alinghi right to be racing under the Bol d'Or, anything goes rules? Email us your views at batmail@thedailysail.com .

And thank you Harry de Jong for correcting our French.

Vestas SailRocket skipper (and former Team Philips crewman) Paul Larsen writes that he likes cats:

For this particular application, my money would be on the catamaran design. In fact when you look at the tri’s ‘withered’ central hull, the two are so similar as to almost negate the argument. Once they are both in their designed sailing mode i.e. flying on one hull, they are very similar boats with similar problems. Considering how quickly these boats will adopt some angle of heel, why carry the weight and windage of a central hull when the structure can be done just as well with thin poles and modern super thin rigging? I don’t think that the old school ‘wetted area’ argument in favour of a tri really applies to how these craft will be sailed.

The hydrodynamic factors affecting a tri should be the same as a cat once in this mode. For this reason a cat should have lifting foils just like a tri. For these two boats the loads on the bows should be very similar and the cat should be no more susceptible to bow failure than the tri... especially as the forestay loads will be carried by the under slung rigging and not attached to the outer bows as on a normal cat. The only time a cats bows will be subject to different and potentially hazardous loads in relation to those of a tri is when, as Adrian Thompson pointed out, both hulls are pressed into the water at the same time and subject to different wave patterns i.e. down-wind offshore.

Considering that both boats look optimised for flat water, I find it surprising that the Oracle tri hasn’t used a dolphin striker set up on the main beam which would greatly reduce weight and add stiffness in a key area. They have the hull there as a support/compression structure... why not use it? Maybe it is because they didn’t know the final venue and had to keep the option open for rougher water. Under slung rigging can get pretty draggy in rough water.

It appears that the foil solution on the Alinghi cat is double purpose i.e. upwind/downwind. I'm semi-speculating here on relatively little info. I’ve only seen one picture but it has me thinking that they will be canting foils. This could also explain what appears to be an engine of sorts on the back of the aft beam. So, Upright when going upwind and canted inwards for downwind work. It makes sense as the technology is available/proven elsewhere in sailing. This means that they will have one less substantial foil in the water than Oracle... maybe two less if you include flying the windward rudder. I wonder if Oracle plan to stick with the centrally mounted rudder on the tri. It will be very interesting to see how the boat behaves when sailing at high speed upwind if the foils still have any residual angle. If they are still partially inclined then there will be a nose up/down tendency when the rudder input changes the angle of attack i.e. a tack input should cause the bow to lift which may be desirable.

The possibility of powered winches is an interesting one as many aspects from foil cant to mainsheet could be push button operations. I almost hate to say it... but on boats like this... I like this option. I say ‘hate’ because it means that the glory of gliding one of these magnificently graceful birds around a course would be done to the backing track of some little smelly stressed out engine.

So the next and potentially most interesting area is the rig. I wouldn’t write off the possibility of a wing-sail appearing just yet. If one was to appear then it would probably be a plan ‘B’ option as the structure needs to be in place to handle the much higher compressive loads of the plan A’ soft rig. I would expect there would still be a lot more compression on one of these boats even with a wing rig as they are not confined to ‘just’ a wing rig as in the classic ‘C’ class rule... therefore the headsail loads would still need to be considered. With the lessons learnt in the ‘C’ class world and with the considerable talents of Dave Hubbard and Duncan Maclean on each team... I’m sure that both teams are fully aware of their options in the wing sail department... and also that Dave and Duncan are fully up to speed with the capabilities of a modern state-of-the-art soft rig. Things have moved on in soft-rig technology since the ‘C’s first sprouted wings. Cogito style rigs aren’t super difficult to build if you know how. I personally would love to see one as the icing on the Alinghi cake. The mere presence of these two guru's on either team means they are keeping their winged options open and covered ( I wonder why one team didn't get both of them).

The water ballast option is also pretty interesting. It’s a pretty useful weapon to have in the armoury and it works really well on multihulls. It would be a great way for the slightly narrower cat to have the power of the tri up-hill but the ability to lose the weight and fly more easily (due to reduced weight and beam) both do wn-hill (and in super light conditions up-wind).

It might sound funny to call the Oracle boat conservative... but in comparison I think it is a little. I also think they had to play it this way as they didn’t have all the information on such things as venues/ conditions to fully push one weather envelope. What they have done is spent more time on the water gathering information and developing key areas such as rigging, sails and structure.

So I personally like/prefer the cat... but respect the tri... and that’s my ‘two-bobs’ worth. I love what these guys are coming up with. It’s bloody brilliant. Yesterday's future is now and this is what I hoped and expected of it. This is development. The fact is that no-one really knows how this is going to end up and everyone following it is developing an opinion... and that aspect alone makes it interesting.

Bring it on.

Lars Svensson writes:

Having been on Stars and Stripes 1988 60' cat and settled on buying Larus Roc nee Adrian Thompson's old Paragon 60' tri instead, it really boils down to venue (wave action and wind strength and tacking) and upwind performance in relation to true wind. My bets would be on the tri with likely further foil developement and more on water testing.

Either way, this will be a great event for showing the potential of modern technology and what can be achieved by multihulls

Let the fun begin!!