looks like it has a belt (screecher) and suspenders (spinnaker)

Why do the boards flair outward at the top?

boards flare outward at the top so that upwind the board is vertical if all the way down.

http://www.nacra.ca/f20cfoiling-3.jpg

Wow --Looks like they added about 20 to 24 inches of horizontal area to the curved boards and the T foil rudder is visable in the pic.

Wondering what locks the boards in the down position --amazingly strong boards -cases -etc able to carry all the loads .

Don't believe this version would be adjustable --that is able to adjust the foil board angle like A C cats .

Trunks must be different than stock to handle the S board vs. C-board, so yes AoA etc. can be made an option.

As an upgrade kit this makes little sense with the Flying Phantom costing the same as a new Nacra F20c. Add a $5K+ foiling package to the F20c and its $5K more than a boat designed from the ground up to foil. Pegasus didn't have the Flying Phantom option when these were built, and I suspect picked up the F20c at a bargain basement price.

it's more the other way around, the Flying Phantom is a widened F18 [full displacement boat] while the F20C was designed with the curved foils to create semi foiling sailing as standard feature, so optimized to dip back en forth in the water

Has anyone developed an easy method of controling the foiling height ---that is --stabalizing the foiling above water level.

The cup cats used for and aft adjusters --moths use trim tabs .


The tendancy to "dip back en forth in the water" seems like the unwanted characteristic to correct or find a simple solution for .

Higher angles are needed to foil in light winds --once up foiling it seems a lesser angle relative to the hull is needed for optimum speed .

ETNZ did a lot of hull optimization; their initial hull shape, done without full-flying VPP analysis, was found perfectly optimized for full flying when they got the VPP working. This hull shape happens to mirror the Cirrus R pretty closely in rocker and volume. So, I would take the full flying Phantom over modifying a F20c. The F20c is designed to use the hull+foil to get into a semi-planning mode, so it is perhaps a little flatter further aft than ideal. Really the hull shape does not matter much, save enough bow volume to avoid a total wipeout and reducing drag when you're in displacement mode. Difference is the F20c doesn't come stock with board trunks that handle full flying.

Actually it does when you're trying to get the boat going fast enough to get it up on the foils.

The f20c is a better platform to foil because it has a more powerful rig. Getting up on the foils takes power. Trunks can be changed out..and there are already a bunch out there..

Yes, hulls matter when getting up, but again those shapes have already mostly been optimized with the fat sterns and modern rocker profiles.

The flying phantom has 10' carbon beams, >32' carbon rig and full carbon hulls, built by the #1 F18 builder for quality in the world. It is equally as powerful as the F20C and the build quality is likely better (read: stiffer=faster on foils). Again, I'd take the flying phantom over a full-foiling F20C in anything above about 8 kts of breeze.

Yes, the F20C is a good retrofitting platform, but again a lot of work and $10K to add foils to a boat that is just as expensive as the flying phantom to begin with. It doesn't make economic sense unless you find a F20C for less than $20K.

Had some health issues --so --have been out of the loop for a while --just catching up .

Some thoughts on foil design and configurations.

,In other words -design idea B S ing ;]

Some class rules prohibit boards or foils outside hull beam ,as result boards and foils have been designed inward from the hulls --the c shapes S shapes L shapes of lifting foils are inward from hull beam .

In proposing a 20 class it might be advantagous to allow them outside hull beam .

In example -With canted hulls the foils could follow the hull line cant below the waterline and angle outward in a T shape--or -- Another very different option would be an inverted Pi symbol type configuration from the hull . Two smaller paralell boards with a base lifting foil in each hull .

Not sure if I,ll "built it " my thoughts currently are to build a 32 ft cruising cat --but what fun it would be as a foiler when the wind kicked in .

have fun .

Carl

I'm sure foils extending past the max beam is more efficient, but dang that's got to be tricky at a crowded starting line or turn buoy.

Sort of like a bunch of H-18 with wing racks all going at it... except you can't see the foils nearly as well...

Brainstorming...slightly canted straight boards (~6°) with L's at the bottom...no curves. "Simple", easy to build, 3 part mold. Insert from bottom. Remove L-foils for beach races, insert regular straight boards from top.

Or build a set of c-boards and t-foil rudders for 98% lift and potentially less drag when it goes light.