Looking at a basic jpeg of a bar chart that is too big to attach (668kb!) I can see that the cost per ton to build and operate different types of warship vary substantially.
All per ton per year
Type: (build) operate
35,000t BB: (£8.79) £10.89
35,000t BC: (£8.79) £13.55
23,000t CV: (£11.45)...