After crunching the numbers in my head, the only over-riding philosophy for going bluewater to me would mean get a boat thats either:
1) Paid for/off completely (cash)
2) Pay for the boat with home-equity or other sources of cash
If you're going to buy a bluewater boat, even those as storied as Valiants, will require you to have insurance and all the associated restrictions/covenants that go along with it. Bluewater insurance on a boat thats got a note on it is prohibitively expensive.
Now, if you get a boat with cash or home equity - there's a certain aspect of "self insurance" that goes along with it. Have enough equity on top of it to be able to limp back home if something happens to your bluewater yacht.