Personally I don't think RTR mad a big change to naval combat, but they made it much more managable wich makes it more enjoyable.

All of it was text based changes, they increases the size of a ship while making them cheaper to maintain. But the biggest kicker is even at 100-1 odds you can still gain a star.

W/o any modding Naval combat can be tedious and annoying with the A.I. destroying fleet after fleet on very hard difficulty. In vanilla 3-1 odds is what you need for a win and a lot of them will be pyhrric with the occasional loss of the whole fleet or just a plain loss about one third of the time.