REPAIR THE PROBLEM
I fixed mine 2 yrs ago. The laminate was peeling off, the fiddle board had inadvertently been pulled of by a friend, and the plywood was feeling a little spongy. On my boat this was due to the leaking head portlight. Whenever it rained the counter would always get soaking wet. If this is the case in your boat I would fix the leak first. I then went to home depot and purchased white formica--cheap. Then, I stripped all of the old laminate from the plywood with a scraper and liberally applied thin epoxy to the wood and let it soak in and harden. Then, I traced the exact shape of the counter onto a piece of wrapping paper with a pencil and transferred that to the formica and cut it out. Then I mixed epoxy with filler(to make a paste) and epoxied the formica down. Put down corner sealant and attached the fiddle board. I also backed the fiddle board with 1X1 teak stock as the origial configuration had the fiddle screwed into the edge of the plywood---not very strong or secure at all. With 1X1 teak stock behind the fiddle I could the anchor the teak stock to the upper surface of the plywood and drill through the fiddle to the stock to anchor the fiddle--much stronger. It still looks great and is very strong. I don't think you can buy a new cabinet as these were probably made as the boat was being finished out simply by measuring. You will find the the counter is not square at all. Also, I replaced the cheap, plastic, discolored, junky sink bowl with a stainless bowl which a bought at West Marine for 30 bucks. Good luck with your project and make sure you don't have a gate valve in place draining that sink.