In summary, I'd simply say "spares and maintenance". For example compare the standing rigging, chainplates and turnbuckles of that 37 footer with those of the 30 footer.
To dig deeper, the other consideration is the purpose the boat is set up for. A 37 footer set up for long distance cruising will cost a lot more to maintain than a 30 footer set up for daysailing. However, if the same 30 footer is also set up for long distance cruising, it's comparable upkeep expense will also rise well above that of the daysailer simply because it will be fitted with a lot more or heavier duty expensive stuff that breaks and needs fixing or replacing eventually. In fact, with items like electronics and navigation, it's entirely within the realms of possibility that a 30 footer could have near or as much invested financially as a 37 footer.
To dig deeper, the other consideration is the purpose the boat is set up for. A 37 footer set up for long distance cruising will cost a lot more to maintain than a 30 footer set up for daysailing. However, if the same 30 footer is also set up for long distance cruising, it's comparable upkeep expense will also rise well above that of the daysailer simply because it will be fitted with a lot more or heavier duty expensive stuff that breaks and needs fixing or replacing eventually. In fact, with items like electronics and navigation, it's entirely within the realms of possibility that a 30 footer could have near or as much invested financially as a 37 footer.
