Fandoms set around classic Royal Navy era narratives, Master and Commander, Hornblower, Nelson and Napoleon (does that exist? Is it horribly wrong that I think I could write it? Let us hope that the answers are no and yes in that order ...)

It's a generic term used by costumers, publishers, and, I think, fans who are focussed on that area of interest. Alas, my only fandom is HP, but my lovely friends who are deeply into Age of Sail recommend it to me highly.

And I know you're not talking about me because I am the anti-prolific ;-)