Then, naturally, I make some fatal error in front of the boss, causing him to absolutely lose it on me, sometimes threatening to take my job away.
Yeah, you'll figure it out, alright.
But driving a TSI raft requires developing a skill, not simply following a procedure. A skill can adapt to a change in environment; a procedure cannot. (It's like a computer program that's coded to handle a thrown error, versus one that is not.)
It's much easier to teach a procedure, but far more effective in the long term to have developed skills.