Team Lalou's new Multi 50 trimaran

Photo from Voiles et Voiliers. Looks like it's taking the planing float concept to the max with nearly square section main hull and floats at the transom.

 

Hello High Tech World ....
...welcome to the world of Sharpie Hulls!!!

Best Regards, Michel

 

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I wonder if they have a retractable step on that thing?(like hydroptere.ch) There appears to be a hollow between midships and the transom if you hold a straight edge up to the screen.

 

Here is the link and translated caption from the picture on Voiles et Voiliers. Looks like there is a dish in the rear of the float similar to the ones on Actual.

http://www.voilesetvoiliers.com/popup/multi50-arkema-region-aquitaine-la-haut-l-hallu-de-lalou/

Original, Multi50 Lalou Roucayrol launched this weekend at Le Verdon-sur-Mer! Signed Neyhousser Romaric, who worked with Benjamin Muyl and Guillaume Verdier, this cousin has Actual dishes and large floats in the middle, close to a F18, a central hull thinner than Yves Le Blévec a platform shape fake "X" for a boat more focused mass deckhouse worked ... Arkema-Region Aquitaine should start in the race at the Grand Prix Guyader, early May to Douarnenez. / HH

 

What do you mean by "dish"-the hollow at the transom?

 

I do not see any dagger boards in the amas, only in the center hull. does that mean they do not intend to fly the main hull?

 

No foils allowed that develop vertical lift(except those grandfathered in) in this Class. The Rule. See thread link below.

2.6.4 Lift-
General remarks:appendages must not provide vertical lift (beyond the Archimedes principle and lift relating to the heel of the boat).
For the requirements of these rules,a lifting plane is all or part of an appendage which could create vertical lift at zero heel,with the exception
of the following:
-*‐Rudder blade whose maximum angle along the longitudinal axis is less than
10°,at zero heel and with the steering centred. Any protrusion of less
than 10 mm on a section of the appendage, measured at its attachment point,
and extending less than 50mm from the profile(fences).

Any appendage shape which could provide lift (beyond the Archimedes principle) by acting as a foil is strictly forbidden,as well as any angulation of
daggerboards. Plates which create a lifting surface on rudders and daggerboards are forbidden.
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http://www.boatdesign.net/forums/multihulls/multi-50-design-rule-no-vertical-lift-44166.html

 

That or they went with stitch-n-glue

 

Doug,

You can still have dagger boards in the ama that do not produce vertical lift within those rules. If you have enough drive in the sails it is potentical that the center hull would clear the water surface even without lifting foils. But in this design there would be no lateral resistance without a dagger board in the amas.

do the rules specifically prohibit dagger boards in the ama? even thought they clearly allow rudders?

 

Was there not a restriction on the number of foils they could use?

 

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No-not prohibited...

 

Prince de Bretagne is the only Multi50 trimaran with ama daggerboards. It's competitive but not outstanding. The rule also doesn't allow canting rigs so the Multi50's don't stay as powered up at high angles of heel. So they are mostly sailed with the main hull just skimming the surface and the daggerboard acting as a surface piercing foil it's also a useful safety feature as the boat will side slip if the main hull flys too high. The dish could also be refered to as a scalloped section at the rear of the float hull. Probably better observed in this other photo. The square section hulls are interesting maybe the potentially improved fineness ratio is considered to overcome the wetted surface area penalty of the shape.

 

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I'd like understand why the hollow in the bottom..

 

Hollow

Most of the hydrodynamic lift of a hull is gained 1/3 from the bow. To counter this lift and to prevent stern suction, so that the whole hull is running even with reduced wetted surface, a slight hollow section in the last 1/3 is placed.

 

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Thanks Manfred. That being the case you'd think hydroptere.ch would have such a hollow aft or any number of other multihulls. There must be some disagrement as to the viability of the "hollow" solution. Seems like, to me, that the hollow would create a suction which doesn't seem beneficial at all?