Gunboat is the no-press version of Diplomacy. Successful gunboat players have a knack for predicting moves, strategy, and stalemate lines, and can manage to pull off rather impressive coordinated feats despite not being able to say a word -- for example, organizing a 4-power coalition against a solo threat and successfully reducing the draw to 3. But because it requires a lot of predictive ability, reading of subtle nonverbal cues, strategic vision, and knowledge of stalemate lines, it is very easy for multiple talented gunboaters to give up a solo victory despite all of them knowing how to stop the solo threat, simply because there is one less experienced player who cannot uphold his end of the bargain.
Gunboaters tend to rage pretty hard about those kinds of situations as well, and it's understandable as to why; when you've done something as difficult as fulfilling your part in stopping a solo, had multiple other people do the same, and then still not get rewarded because of someone else's error, all because you just couldn't say a few words to get that player on the same page as everyone else, it's extremely frustrating. I know I personally tend to get pretty pissed when it happens (though fortunately I manage not to yell on the forums about it... tooooo much...).
But at the same time, this thing is tough. It doesn't feel tough once you "get it," but if you don't "get it" then it's nearly impossible to figure out how you went wrong and improve. So I'm encouraging my fellow gunboaters to be more supportive of newer players in those situations, because I know I was terrible to start and I'm sure I'm not alone.