That story remembers me of another one, with airplanes, not boats.
I was a 18 year's old kid, but already a pilot with some experience (I was training younger kids) when an Air force Major, that was that day the field instructor, asked me to go with his friend, a 10 000 hour civilian middle age pilot (from a big Air company), for an airplane ride.
The plane was an Auster. I took off and the guy asked me to assume control of the plane and we start to make some tight turns that scared the hell out of me. No I was not afraid of tight maneuvers I was afraid because I understood that the guy did not know what he was doing. He was losing altitude in the turns without noticing, increasing the airplane speed to near the limits it could break. I was forced to call his attention to it and when he pulled the airplane up without taking out some engine (putting a lot of Gs on the wings) I had to do that myself excusing to be interfering with his flight.
When we come down I was quite relieved and asked him if he wanted me to land the airplane (hoping he said yes) but he said no.... Well, what could go wrong? Even in a messy landing the plane should take it.
With some Zig-Zags he managed to align the plane (it was an airforce landing strip, quite wide) he put it parallel to the stripe and then without waiting for the airplane to lose enough speed, pulled the stick sharply back, without giving me any chance to correct that. Maybe that's how he used to do on a 747, but that does not work on a light plane. We went up before falling down from 3 meters high
We lost the landing gear, the propeller and had lots of luck in not having capsized the thing, that was gliding over the engine making a huge noise and a lot of sparks. I jumped the plane before it stopped, furious with myself for letting him land the plane!
Well, that was my lesson, the one that match your own. From that day on I learned that things are not always what they seem and started to have a lot more care in who I was putting my trust with