That is why then. The good water to the jet foot means alot. The vortex in the impeller is pretty sketchy, any bubbles off a dent in the bottom of a flat boat, leaf, rock, stick, can mess up the vortex and lose power.
We went over a log on the 11 Pt one time and put a small dent under the boat in front of the motor. That messed up the flow of water back to the impeller and we had to limp back home. Barely.