WORK IN PROGRESS.
Websites of companies that can help you register a vessel:
International Ship Registries (Worldwide) LLC
Offshore companies and yacht registrations
Other places to get information:
Guide to Ship Registries
List of flags of convenience (Wikipedia)
COMPARISON OF FLAG STATE LAWS ON ARMED GUARDS AND ARMS ON BOARD
Legality of cannabis by country
Prostitution law
Gambling law
State of World Liberty Index
5 MOST LIBERTARIAN COUNTRIES – WHAT IS THE MOST LIBERTARIAN COUNTRY?
Favorable laws for freedom-loving vessel owners:
Very basic ownership requirements.
Lax rules about firearms onboard.
Loose laws on "vices" (prostitution, gambling, drugs, etc).
Favorable conditions for lax enforcement on yachts and cruise ships (this is NOT a comprehensive list):
Poor countries with already weak law enforcement. Examples are:
Somalia.
Cambodia.
Honduras.
Burma/Myanmar.
Countries (especially island countries) with small populations. Examples are:
Tuvalu.
Landlocked countries. Examples are:
Bolivia.
Mongolia.
Moldova.
Or, obviously, a combination of these factors.