The better Pre-Renaissance naval battles

This is a concept that wasn't great in both CIV and CiV. Units couldn't cross oceans until the Renaissance Era, which makes for really easy games due to isolated starts. You are guaranteed safety from invasion until Astronomy, making even Immortal difficulty a bliss. And although it is technically realistic, it doesn't scale well with CiV.

There were many intense naval battles in history that all happened before the Renaissance Era. One example is the Persian invasion of Greece. Admiral what's-his-name defeated the Persian army from the sea. People could navigate across seas to link up with Egypt, Greek city-states, and various other must-trade-with destinations. Obviously, there were still areas that they couldn't sail (i.e. across the Atlantic) but any distance less than 200 miles was a breeze, if you'll excuse the pun. Certainly there must be a way to simulate naval warfare before Astronomy that allows micromanagement of a fleet, while leaving ocean tiles unsailable. This is why I propose a new kind of ocean tile.

I propose a new tile: The sea tile, different from ocean tiles and coast tiles. It offers the same food/gold bonus as an ocean tile, but embarked units can move over these tiles at one movement speed, and pre-Ren naval units can move over them at one third their normal speed. This will allow intense, pre-Ren naval battles to take place, making Great Admirals spawn more, and allowing civs with naval UA's and UU's to utilize their units more. These sea tiles would surround continents in rings of 3-6, allowing much more exploration, and possibly creating ocean bridges to other continents.

Thoughts, ideas, criticisms welcome.

I think sea tiles should use up all of an embarked unit's move points, not just 1.

Sorry for not specifying, that's what I meant. Embarked units would use up all of their movement points, and naval units would use up 2.