I have emailed this query to Waterways Ireland today:
I would be grateful if you could tell me
(b) which, if any, authorised persons have been provided with training and instruction in the exercise of the power of arrest, as provided for in Section 13 (2) (b), and have been issued with warrants as
provided for in Section 13 (2) (c).
I note in Section 17 that
(9) Every authorised person appointed under this section shall be furnished with a warrant of his or her appointment as an authorised person and when exercising any power conferred on him or her by this Part as an authorised person shall, unless in uniform, if requested by a person affected, produce the warrant or a copy thereof to that person.
I regret that I had not noticed those provisions earlier.