So i have been collecting battlepoints to upgrade my academy to level 6. What i did was filled my boat (65 slot tavern) with 6 juggs, 32 gunners and rest bombers and took out 12 targets (boats, royal navy and couple of monsters all over the map) with my lvl 6 ship. I collected around 6 battered chests, As i was opening them 2 of them gave me 120 BPs while the 3rd one blew my mind (Check the screenshot). Although it was a battered chest but it has 6 slots. I have also been hitting 5 star serpent along star isle, it gives way better BPs then 5 star bigger fish at isla nublar. I got 800 and 600 (screenshot refers). Try it yourself.