What are the critererions used to calculate maximum allowable number of passengers on a passenger/RoRo ship?

Question

I want to know how the max. allowable no. of passengers for a passenger/RoRo ship is calculated, Criterions and formulas used for this purpose, who determines the passenger capacity of a ship involved in international journeys, or any FREE resources where I can find this information.

Answer 1

passenger capacities are set by the National Authority of the country where the ship is registered; all reputable NAs work from the SOLAS ( Safety of Life at Sea) standards set by the International Maritime Organization ( www.imo.org) so start there.
Lloyd's Register of Shipping, the American Bureau of Shipping and DNV are the big 3 classification societies..ie private firms that inspect ships and set standards based on IMO regs, so you could also look at them for more info......

Answer 2

Are they telling you there is not enough room for you? On a RoRo ship i assume passenger wieght would not be an issue, i am sure it is a fomula derived from square footage of passenger space, cabin space, bathrooms, and life rafts, crew members etc...i would think if you call the coast gaurd they could tell you more
for international vessels the country where the boat is registered would have the say so, i assume