I expect the reason for the hand to hand combat to be harder is to make it more difficult when boarding ships, for example on sailer level you might board a ship with half of what your enemy has and still take the ship without loosing that many men, while the ship to ship battle maybe easy the boarding is made harder to put you off the idea of boarding a ship too quickly and winning the battle. Back in those day's most captains would perhaps have liked to capture the ships rather than sink them but not all ships could be captured and the only thing available would be to sink the ship. A captain wouldn't attempt to board in less he was sure he could win or he knew the chances of winning the battle was almost impossible and he couldn't escape, so he took his chances trying to board. The easy way to make the sea combat a little more harder is edit the ships and make them all stronger, the problem is, its alway's going to be the same amount of crew so you can easily blast the crew with grape/bombs and board if you increase the maximum crew sizes per ship you increase the ships running costs and it starts to move from realistic to stupid, a Sloop with 500 crew is a laugh, yes Black Beard had a ship the Queen Ann's Revenge which could carry a large amount of crew and had as many as 40 guns but it wasn't a Sloop, perhaps a Schooner, Packet Brig or other similar ship. Anyway pirates had there own way's of improving there chances of slowing a ship down via a shot type that would ignight the sails etc and for obvious reasons having something like that in this or any pirate rpg would make it too easy so to make it close to realistic as possible is not alway's the best way to go about things, my tip is don't try to board the ships so quickly, more so when at such a low rank and have plenty of potions ready just in case, and enough bullets to see of a few troops, i alway's have 20 bullets and 10 potions, any officer's with me have 40 bullets and as much potions as they can carry.