Paradox Testing Update

The marine side of Carbonix has been busy validating the production setup for Version 3 of our Paradox A Class catamaran.

Launching from our base on Cockatoo Island, sailors with Moth, multihull, and skiff backgrounds have piloted the boat, contributing valuable feedback.

Here are some pics with notes on some of the specific innovative solutions being tested.


Boat all set up ready to launch: L foils are already in, and raised. Nothing loose on the trampoline, and virtually the same ground clearance as a non foiling boat. Just launch and sail away.


Foil rake adjustment: Carbon cover plate fastened to the deck captures the top bearing/slider. It also incorporates the worm wheel holder, and worm screw bearings.

Removing the cover plate gives access to the foil case, and allows fast swapping of sliders as needed.

Cases will accept C, Z, and J foils as well as the standard Ls. Ls are just the most stable and proven option, making performance more accessible.

Swapping out the top slider and bottom bearing block lets you change to other foil profiles quickly using only an Allen key.

Future updates to the control system can be incorporated by replacing or modifying the cover plate, without surgery to the deck.

Note that there is space at the rear of the cover plate to accommodate additional cam cleats, should individual owners prefer a rope purchase system for rake adjustment. Again this can be experimented with independently, with no mods to the deck. The cover plate is held in place only by the titanium screws visible in the pics.

In the image below you can also see the neat detailing of the sidestay anchor point.


The green and white line running over the tramp from the worm wheel is used to adjust foil angle of attack. No cleats.

Moving the rope in the direction of the arrow drawn on the trampoline puts more rake on both foils. Once adjusted, the worm system stays where you put it, precisely.

Thick blue rope is the sail down-haul tail. Thinner blue rope controls mast rotation. This arrangement takes care of foil rake adjustment with a single line.


Foil retraction: Retracting the windward foil maximises righting moment and improves heave stability. To make the job easier, we have developed a system that automates foil retraction and allows lowering with one hand, from anywhere on the boat.

This actually makes foil handling easier than it used to be. Conventionally the process was: uncleat a downline, physically grab the top of the foil, pull it up/in, then re-cleat to hold the new position. Now just releasing the downline lets the foil come up unaided. Pulling the downline lowers it.

Below you can see our new foil top fitting. It incorporates a swivel mechanism that allows the cleat to rotate 360 degrees so it can face you whether you are sitting in, or out on trapeze. Thus the foil can be deployed before a maneuver while you are on the wire, or afterward from on the tramp.


The red line is the 3:1 foil lowering rope. It runs up through the middle of a swivel fitting to a cam cleat atop the foil. The cleat can be operated from any direction (inboard, outboard, forward or behind).

Just visible is the retraction elastic that pulls the foil up and keeps it there. It goes up to a turning block on the sidestay, then runs down to the thimble at the bottom of the sidestay. Since the elastic is very long, the force it exerts during retraction is relatively linear.


As you can see below, when the windward foil is up, it clears the water easily.

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Steering: The inboard rudders mean the hulls leave a remarkably clean wake. No more ‘bubbling’ and draggy turbulence from water coming off the hull hitting conventional outboard cassette hardware.


Wake off the leeward hull comes off cleanly. On the windward side you can see the end-plating effect: Water thrown up by the rudder is redirected down and back by the hull. Since the local normal to the hull surface has a forward component, there is some energy recovery.


Nice upwind trim: Leeward hull at high lift-fraction, windward foil raised… Flat and fast, with much reduced windage (aero drag) thanks to low profile bows and streamlined rear beam. Deck sweeper sail coming soon.

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‘Spy shot’ from Catacare showing Selim Kakis experimenting with upwind foiling. Flying on the leeward foil maximises the possibility of this being effective since the full righting moment lever remains available.

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And another sequence showing Scott Babbage also playing with upwind flight. Note that the boat is climbing to windward during the whole sequence (look at the landmarks in the background). These are stills from very shaky videos. Better footage coming soon.

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And finally a few downwind runs…

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Merry Christmas, and best wishes for 2016!

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    • Jose Dauden
      Sunday, December 27, 2015

      Congratulations, this is BY FAR the coolest A-Cat in the World. Incredible thinking, details functionality – really outstanding!!
      Cheers, and all the best success!

    • Brett Fiala
      Wednesday, December 30, 2015

      Looking good I can’t wait happy holidays

    • Tony Grainger
      Thursday, December 31, 2015

      beeyootiful bit of gear – love that chainplate attachment – simple but effective!