Who can leave a review?
Only guests who actually took the trip. A review can only be written against a booking that has been marked completed, so nothing on this site comes from someone who never sailed.
Reviews are tied to bookings in the database. No booking, no review — which means a captain cannot post about themselves, a rival cannot post about them, and nobody can review a trip they only thought about taking.
It is a smaller number of reviews than a site with open submissions would show. It is also worth more when you are deciding who to trust with a day of your holiday.
The review appears on the captain's listing, where the next guest deciding whether to spend a day of their holiday on that boat will read it. Write it with that reader in mind. The things they want to know are the things you wanted to know before you booked.