Re: Mare Germanicum
The porpoises have absolutely no interest in attacking a boat. Even if that just means getting close and harassing. Boats are wood, and porpoises are not, and when the two bump, it hurts much less to be the boat. Also, Humans are known to carry the dreaded Pointy Sticks With Ropes. Not only can they skewer you, but they can pull you in and cut you apart, or even drag you onto their boat! They have even done this with whales. Cetaceans of all sorts have learned to be respectfully cautious of boats.
While Ongriss is off negotiating with the ancestors of future Seaworld performers, Vincentas cuts off one boat. One advantage to the enemy splitting up- it greatly evened up the odds. Also, the boat he caught was the slowest, and from the looks of things, the most heavily laden.
The leader of the boat stands up, and shouts back to Vincentas: “It’s my booty, rightfully taken, but I will give you a share as a gesture of friendship before the gods!”
Vincentas knows something of the culture of the Scanians. To them, there's not much difference between "seaman" and "pirate". They see nothing wrong with raiding someone else's riches. After all, what right did other people have to be so wealthy? This offer is their way of avoiding a fight. But it may not be because the Scanians are afraid of losing. Ships with valuable goods on board do not attack, they run home, so clearly Vincentas is the one to gain, here. With nothing to gain themselves by fighting, the Scanians have no reason, even if they think they could win.