Ok, so as you can see here
(I posted pics in our Dolls Guild Thread) - there are big diffences in the Boss vs their normal couterparts...
Attacking these alone when you first meet them as a pirate would be an almost impossible chalenge - true - at L40 you could probably take the bosses no problem - but since you will run into them as a new player much earlier, you will defiitely need help
Gravedigger... Normal > 75HP - Boss > 675HP
Brigand... Normal > 1450HP - Boss > 3100HP
Raider... Normal > 2650HP but our Boss... over 5900HP