I have to ask .... When (year) did this incident occur, and in what country?
You have stated that inland rules applied, but that this was in an area
that involved an extended channel towards the seabuoy. Normally, the
demarcation will be at a breakwater or some point before the seabuoy,
hence the reason for my question as it will greatly influence the rules
being used.
BTW. There are many places that will require a particular passage of a
seabuoy, be it to Port or to Stbd.
As stated, I wish more would ask questions on this and try to supply
answers (right or wrong) as it's a good exercise.

otn