Not to derail this thread further, but the Wharram Wingsail Rig (the boomless design) came later.
Originally the Pahi's had booms, either conventional or wishbone, but the Wingsail Rig was offered later as an option.
The original Pahi 31 rig is a Bermudan cutter, with low cut, anti-twist, loose footed mainsail, but now she is also available with the Wharram Wingsail Rig, giving more clear centre deck space as the mast is placed further forward.
The Wingsail rig was devleoped in 1981 for Wharram's new Tiki models.
...we developed the TIKI sail in 1981 for the then new TIKI 21 Coastal Trek Catamaran
The Wingsail Rig is very efficient. It is not really a 'gaff rig' in the old sense. In modern terms essentially it is similar to a square top main, but also with a luff pocket that emulates some aspects of a wing mast.
Wharrams perform badly when they are built poorly and sailed poorly, often by non-sailors.
Built and sailed well, their performance can be very good.
As designed the hulls (should be) light weight and have good speed to length ratios.
Here is a great example, a French Wharram Tiki 38 averaging speeds in the low teens and hitting top speeds in the high teens. Throttle back and you could have a solid 10kn boat
speed in trade wind
conditions and with the Wharram Wind Vane steering
Wet though, like most performance boats at those speeds, so they need a good dodger