There are two schools of thought on rudder foils in regards to long thin hulls ( unlike dinghys skiffs with fat short hulls ), one being any foil in the water is drag and is simply countering a poorly designed hull. The other is that the foil is stabilising the boat and thus allowing the boat to be more longitudinally stable enabling the gorilla on board to sail the boat better. Having a gantry simply, by a longer leverage, allows a smaller foil to have a greater effect.

So far the jury is out on both counts, as a development class we should be encouraging this sort of development as it may ( or may not ) lead to an easier to sail boats.