Foiling is not how it seems . It is the leeward hull that rises on a Ketterman Trifoiler, not the windward. The drawing you have added would lift the stern and bury the nose on the windward hull and the opposite on the leeward. If it were foiling it would raise that hull but that would be exactly what a foiler would not want. We dont foil on catamarans so trying to use a foil to balance the boat rather than sailing it balance must be couterproducetive. T foils temporarily correct an ill balanced boat. That is why they are so effective.

Have a look at the following for how the Ketterman works. It's very interesting.http://www.hobiecat.com/support/pdfs/trifoiler_manual.pdf