The reason for that lift is simple. Imagine a very simple propeller with four flat blades set at a 45-degree angle to the propeller shaft. If that prop shaft is flat to the surface of the water, then all four blades attack the water at the same 45-degree angle and provide equal, constant thrust. But with that shaft inclined 15 degrees, the blade rising from down deep up toward the hull is only attacking the water at 30 degrees from horizontal — pulling the boat forward — while the blade turning down, away from the hull, is at 60 degrees — pushing the stern up. With pods’ zero shaft angle, the blades are at equal angles in relation to the water through their entire revolution, so they thrust the boat forward without lifting the stern.