How do reviews work?
Only guests who actually took a trip can leave one, and every review is read before it is published. Critical reviews are published; that is the point of having them.
A review can only be written against a booking recorded as completed, so nobody can review a trip they did not take and no competitor can post about your boat.
Moderation removes phone numbers, personal details and abuse. It does not remove criticism. A one-star review describing a genuinely poor day will go up.
Reviews appear on your listing with the rating and the guest's words, and your overall rating is the average across them. New listings start with none, which is normal — a listing with three honest reviews from real trips outperforms one with fifty from a site that does not check who wrote them.