In Rome2 you can move your troops off the land and they will get into transport ships, the faction I chose started with a boat and I also made a few more with the harbor. Now the enemy moved his troops into the water so I tought it would be an excelent time to take his transport ships down. But right before the battle started my winning chance was really low. But I went ahead with it anyway and got utterly destroyed, their boats were stronger then mine and even more filled with troops then mine. Their army of Javelin throwers were greatly outnumbering my Javelin thrower boats. Not to mention their melee troops just ram your boats and start taking them over.
So what is the point of building boats from your harbor and not just placing your troops on the water?