16851 boat mail seat availability

I'm happy to help you with your query!

It seems like you're asking about the availability of seats on a boat with the registration number 16851. Could you please provide more context or clarify what you mean by "boat mail seat availability"? Are you trying to book a seat on a boat, or are you looking for information about the boat's capacity or layout?

Additionally, I'd like to know what kind of boat this is (e.g., ferry, cruise ship, private yacht) and what type of trip or journey you're planning. This will help me provide a more accurate and relevant response.

Please feel free to provide more details, and I'll do my best to assist you!