Have you counted the number of Maritime & Shanty Festivals that are held both in the UK and around the globe? In the last decade or so there has been a significant increase in the number of shanty groups as well as folk singers featuring mainly maritime material.
The rise in popularity of maritime festivals can be favourably compared with the folk revival of the early 60's.
So I would say that there are perhaps more than just a few enthusiasts who like shanties!!