Until the Industrial Age and the mechanization of naval forces when all the powers of the world switched from wooden navies to metal navies there was a single... ahem ... a single naval battle that did NOT happen within sight of the shore.
Pay no attention to the movies. To say that open sea naval battles in the age of wooden navies are rare would be a gross understatement. There are a large number of reasons for this, among them the fact that on the open sea the odds of finding your enemy are a thousand to one or greater.
If we assume, which I don't think is unreasonable, that those who die in a naval battle near the coast will be able to return to their bodies then I think we should be clear on how many people open ocean perma-death is actually going to effect. Provided you aren't deliberately executed this way it's pretty unlikely.
The reason it is set up this way is because of the great rewards inherent to successfully braving the open ocean, the risks are equally great. However, this isn't going to be an issue for the those who use the navy for military purposes, it's really only going to effect explorers and colonists.