Sorry Bob,
physics is physics, regardless of which craft it is applied. It applies to Ballistic missiles, as much as human body movement. to apply force to an object, not directed through the COG( and absent of any other force) will cause the object to spin. as I said before, airboats have two forces, the thrust from the engine, and the hull pressing on the water( the hull lifting out of the water is not a function of the water propeller pushing the hull up, rather the force of the water on the rake/strakes lifts the hull, or, how else do surfboards plane with no propellers?), which will conteract the 'spin' if it is not accounted for otherwise. This does leave problems, such as blow over, and less efficient use( read speed ) of engine power.
the Dragon ( my boat) is not the only one with negative AOA, http://www2.towerhobbies.com/cgi-bin...=LXBTC1**&P=ML of course is commercially made boat, assumeably with professional engineering, and also clearly shows the negative AOA. Positive AOA works very well with pullers ( again my boat, the yellow one) utilizes a positive AOA, but to pull through the COG. The negative AOA will work if with a pusher, due to the point of thrust being in the rear, but still thrust goes through( or is parallel to, ) the COG. although the aquacraft is a puller, the AOA is still parallel to the line through the COG. to look at it a different way, it is also parallel to the water, when the boat is at plane.