Ask a Canada Law Question, Get an Answer ASAP!
If he was working on something that you created he does not own the copyright.
His being a coach gives him no right whatsoever.
Had he been your employer and you had created this work during the course of your employment then in the absence of an agreement to the contrary he would own the copyright to this work. That is not the case here.
I suggest that you nip this in the bud by paying a lawyer a fee which will be fairly small to send this coach a letter asserting your rights and threatening a lawsuit.