Killing On The High Seas
The battleship was the most complex machine of that era, requiring hundreds of sailors in addition to the many specialists (armorer, cook, cooper, surgeon, carpenter, etc). This is a machine (which, I know, sounds a bit wonky, one doesn't think of something that doesn't have an engine or at least a very prominent smoke stack to be a machine; a bit of rope, some sail, and alot of wood hardly constitutes one) which controlled the only means of overseas trade, --from the West or East Indies, from the Americas-- and therefore of wealth, and therefore, ultimately, of power. They were the Star Destroyers of their time.
Killing was done very simply, and much like on land, but with more cannons, heavier cannons. Iron balls of death that weighed as little as 6 to as much as 45lbs would be hurtled at the enemy. If you didn't get maimed or die outright from those, you'd die from splinters of all things, being broken off by impact and hurtling through the air to do the most untoward things to your major arteries, your lesser known internal organs, and generally spiling your blood all over the deck.
If they didn't kill you with roundshot they'd switch to grapeshot or canister shot, which would turn those massive beasts into the sort of shotguns you'd use to hunt elephants if you were interested in both killing the elephant and liquifiying its remains at the same time.
And if they didn't kill you with cannon fire (incidently, while you tried to do the same), they'd board you and you could both have an all out brawl trying to sever important bits off each other using axes and pikes and cutlasses. There was no room on a boarding action for any grace or parry or swordsmanship, much like when infantry would do a bayonet charge, it was all gutter fighting, moreso infact, since there was less room to move, and a drop into the ocean meant a drowning more often than not (many sailors never bothered how to swim, reasoning it was better to die quick than prolong it (this is as if all the sailors were the visitors from Alien Nation, touch water and you die, and you're surrounded by water)).
All the while this was happening they'd often have sharpshooters, as much as they could be, seeing as they had to use smoothbore guns, in the tops of the rigging to shoot down on you as you fired your cannons or steered the ship or tried not to be killed by screaming masses of iron being propelled by explosions.
It was a bloody, vicious affair, a fight of artillery at close range, full of a tsunami of noise and smoke and general chaos that generally accompanied war at that time.