I was quoted among the people for whom naval battles are working fine. However, I have since run into the problem of ships trying to board an enemy vessel while still too far away, which causes the ship to rocket across the map at high speeds, sometimes jumping back and forth, as it tries to land on the enemy. I think this is a problem related to the number of ships in the battle.
When I have small battles - like one ship versus one ship, everything works fine. No problems. Some people fall during boarding, but it seems realistic. When I have battles with three ships or more, the CPU might have difficulty and the algorithm causes various events to take place at different speeds. Thus, for example, the ships try to board too soon and causes them to launch across the sea towards the enemy, but the men still move at a normal pace and so are launched off the ship, falling to death. One solution to this is to not try to board the enemy until you are very close to that enemy. Get close, then push the "K" button to try to board. Do not have "Try to board" on while you are still far away.
I will probably just not engage in naval battles unless I have 50 men or less. More men I can transport without running into pirates anyway, since I outnumber them and they don't want to fight. So overall, unless you like fleet battles, the system works fine as it is. A bit of tweaking to lessen the problem with fleet battles would be good, of course, but if it can't be made to work then I think the system is okay as long as people only go into small battles.
At least, this is my experience. Perhaps others have problems with small naval battles, too.