Size and the term "passengers" are taken right from a government of Canada document online. The type of vessel was either "non commercial " or "recreational", I don't recall which but it definitely referred to a pleasure boat, NOT a commercial boat. Read this the night before I posted while I was looking up some other information. It caught my I so I read it more thoroughly. Next day, presto, this thread appears and I know an answer as far as Canadian boats go.
By definition, in Canada, a passenger vessel is any vessel that carries at least one passenger. A passenger is generally anyone who pays for a trip on a vessel.
Here is the law in Canada:
Navigation Safety Regulations, 2020 (SOR/2020-216)
See section 118
https://laws-lois.justice.gc.ca/eng/regulations/SOR-2020-216/index.html
AIS Class A
118 (1) The following vessels must be fitted with an AIS Class A:
(a) vessels that are 20 m or more in length, other than pleasure crafts;
(b) vessels that carry more than 50 passengers;
(c) vessels transporting substances, materials or articles to which the International Maritime Dangerous Goods Code, published by the IMO, applies;
(d) vessels carrying pollutants, as defined in section 165 of the Act, in bulk;
(e) dredges or floating plants that are located in any place where they constitute a collision hazard to other vessels; and
(f) towboats that are 8 m or more in length.
Marginal note:AIS Class A or B
(2) Every vessel, other than a vessel referred to in subsection (1), that is engaged on a voyage other than a sheltered waters voyage must be fitted with an AIS Class A or an AIS Class B if
(a) it is a passenger vessel; or
(b) the vessel is 8 m or more in length and carries a passenger.