Hello All,
Apart from structural issues, why is the beam on catamarans generally about 1/2 LOA but on trimaran up to 1/1? What would be the difference of a tri sailing on one hull compared to a cat sailing on one hull?

Or is the difference obvious in other conditions? ( tacking, gybing,high seas, a s o )

Would a cat/tri be more prone to dive/get lee helm or something else?

What is the main reason for this difference?

( I'm thinking of making a Cat/Tri with a very modest center hull ( really a central beam for mast support.) or a down-scaled ORMA 60 at about 6 m LOA)

Please tell me what the catch is in this, because I suppose there might very well be a reason why this sort of design is not around.

Would be most grateful for input in this matter.

BR

Patrik Elfving

How 'bout an 18ft. x 12ft. folding cat with a center pod? Sort of like your Cat/Tri. It was called the Batcat.

"On The Wire" Story About the Batcat Catamaran

Source 'the daily sail'

New lake racer
The Daily Sail looks at the new M35 catamaran, a new one design lake racer with a few differences


Following on from our feature on the new RMW40, so TheDailySail was contacted by Gerard Gautier concerning a new project he is part of in Switzerland.

The M35 is another one design catamaran but this one was conceived by Christian Favre (Ventilo) and Rémy Laval-Jeantet and put together by a design team including Alinghi boat builder Bertrand Cardis, Gerard Gautier and designer Sebastien Schmidt who was behind Ernesto Bertarelli's Alinghi lake catamaran and was part of the team behind Lionel Lemonchois' Gitana 60ft tri.

There are several innovations with this boat. As you can see from the illustration above, this boat will also have T-foil rudders to reduce pitching like the RMW40, but more radical is that she will have asymmetric planing hulls. Although this creates more drag in light winds the design team believe that it will allow the new cat to get up on the plane in lower wind speeds and without the need of more complex foil shapes.

Another unusual feature of the cat is that is has a third centre hull out of the water (this is idea was originally to our knowledge first tried out on the Derek Kelsall-designed VSD cat for Nick Keig in the 1970s). The advantage of this is that you get the fore and aft tension in rig as you would with a trimaran to improve upwind performance.

Like the RMW40 the M35 will be built in carbon/foam (rather than Nomex) sandwich and will be demountable. It is also a one design, but the manufacturers are looking to turn this into a sponsored class. As the dimensions below show the boat has a higher power to weight ratio than the RMW40, but this is because it is designed for lake racing and events such as the Bol d'Or, it is not expected that the boat will sail offshore.

The M35 is expected to cost 350,000 Swiss Francs (roughly £150,000) including tax. The manufacturers are looking for six purchasers to get the class going.

Dimensions:
LOA: 35ft (10.70m)
LOA: With bowsprit/centre hull: 46ft 7in (14.20m)
Beam: 25ft 7in (7.80m)
Beam with racks: 31ft 6in (9.60m)
Mast height: 67ft (20.50m)
Displacement: 1,000kg
Mainsail: 76sqm
Solent: 32sqm
Genoa: 59sqm
Reacher 125sqm

Contact: G.Gautier, 3 rte de Riond Bosson 1110 Morges, Switzerland. Tel: +41 21 802 39 28 Fax: +41 21 802 37 33 Email createx@voiles.ch

Say! - anyone in for a 'timeshare'?

I just had to jump on this.

Keeping that cat's central hull ("cat's central hull"?)above the water reduces wetted surface while adding some structural rigidity but I think the whole design is short of the obvious: make it a tri and fly the whole boat out of the water. Nigel Irens has a better trimaran design and they're going for a transatlantic record attempt in 2004. It's been built and is an hour down the road from me.


Go here> http://www.multihullboatbuilder.com/scat/

Dean, The boat looks amazing! Wow! I want a ride! Did I say "WOW!"?