This thread has wandered on and off topic and has made for some interesting reading and points of view. It's amazing how aggressive some become.........
I was interested to read from some that their main reason for taking ship photographs is to post on this site. From my point of view, posting on here is an incidental reason, not the main reason. I suppose the main reason is just a very selfish one, I enjoy doing it for myself, especially if I get a "new to me" ship. I enjoy planning the trips etc., and sorting them out afterwards.
I have restricted myself to posting on here one photograph per vessel name, unless there have been significant changes to the vessel between shots, then I may post a second.
Using the vessel "Hanni" as an example, if I want to look at a photograph of her on here, I'll do a search, and probably just look at the first two or three that come up, so as time goes on, older photographs to me become redundant. It's very rare I'll want to see a photograph for a particular date or location, and almost never will I look by photographer.
As far as I understand it, Shipspotting is not a business. It aims to break even through advertising, but does not look to make a return on invested income, which is a standard definition of a business.
The four photographs per ship name per photographer does seem a reasonable proposition.