Coriolis – 25 Metre Catamaran

The Coriolis Catamaran is a 25M concept design with twin masts, each mast mounted on a hull. The aim of Coriolis is to have a sail powered catamaran that is mainly intended for long distance cruising. With two hulls that are capacious rather than very slender, mean that she is not intended to win races (though probably quite swift), but rather use the twin mast configuration to enable each mast to be more compact and less loaded. It also provides and element of redundancy. It also means that power and loads are distributed more evenly and each mast is placed on structures that are well suited to the purpose; a mast on each pontoon makes more sense than a centrally placed mast, as the compressive loads do not tend to exert on one of the weakest parts of the vessel.

The yacht is intended to be as environmentally friendly as possible, so she is built using vegetable derived epoxy, with flax fibre for her hulls and superstructure. He decking would not be teak but cork; chosen for the renewability of the resource and great insulation plus impact resistance qualities.

She would be available with a choice of a conventional Bermuda rig or alternatively with a couple of wing sails. This design is one that I have been toying around with and is conceptual. It uses a NACA 2412 foil form but has a number of features that should mean that, in theory at least, the foil form could be varied by the use of cams inside the wing. The cams would act on the battens, which in turn would vary the profile depending on the direction of the wind, though this would be selected by the skipper. The sails are unstayed and can rotate fully 360 degrees, if required. This means that the wing sails could be used as wings even with a following wind.

The wings can be raised in a similar way to a junk rig, so the uppermost part of the sail is hoisted, and it raises each segment in turn. The cams that are attached to the battens have loose fitting bearings that not only allow the wing to rotate, but the bearing surface also slides up and down on the mast, though the tolerances would not be very tight, removing therefore chances for the cam “vertebrae” to seize up. The mast would probably be made of pultruded Carbon fibre, meaning tubes that are consistent and can be very stiff. The masts do not taper.

The cam system would probably be powered by electric winches or hydraulics. The sails would have a boom, inside which would be the hoisting mechanism, probably an electrically powered capstan winch.

Twin wing version

The boat would have feathering propellers, but the power to the propellers would be electric, with the propellers being used at times as generators to top up a bank of batteries. There would be a backup diesel generator for situations where it might be needed. The vessel also has numerous solar panels and a couple of wind powered generators at the top of the masts, which would ensure that enough power always exists for primary communications and navigation equipment. The aim of all being that she could sail under wind or electric power for the vast majority of the time, meaning a non-polluting and quiet vessel.

Bermuda Rig Version

On both versions the masts are attached at the top to one another, providing an element of rigidity and mutual support.

Bermuda rig Version
Coriolis has a garage up front to stow away Tenders and/or Jetskis.
Coriolis has a garage for the stowage of tenders or Jetskis.
Twin Wing Version of Coriolis