Ben Coats
Freebooter
i was off minding me' own business, heading from Port of Spain to Port Royale, in a class 3 heavy line ship maxed out with crew/guns/meds, and ran into a spanish military squad of 4 ships, one 1st class, two 2nd class and one 3rd class, i was trying to board the class one so i could just grab it, knock the sails off the others and sail away, well i ended up getting boarded by 3rd class right as i was getting up to 1st class, i defeated them farely quickly, during the boarding action i was able to grab ammo of over 300 bullets from one of the dead gunners. (needless to say i really needed it) then i boarded the 1st class and defeated them, it knocked me down in crew to 120 men, i knocked off the sails of one of the pursuing ships but was boarded by a class 2. all my men were killed, i fought over 40 or so single handedly in the boarding action (hense the use of the bullets when i needed and had them than not had them and needed them) OK here's my question, "How and why did their health take so long to drop?" i had to shoot most all of them @ least 6x's just to get their health in the red where i could finish them off with a sword, it took me almost 45 min of battling it out with them to do so. but i was able to defeat them and my reward is (screenshot below)
Not surprised at level 18. The game will often send opponents that outmatch you quite a but - especially if you are playing on a high difficulty. Sounds like you are having fun anyway! 
MK