one way to look at it...
Average take from an SOS: 20,000 gold (that's 10k+20k+30k, divided by 3).
Therefore, if you took all the gold from your SOS, you'd get (on average) 1333 points per SOS. IF you did 30 SOS a day (40k points per day), that would take 250 days to get the ship. Manage to do 75 a day (possible, if you go out and buy all the SOS that people don't like doing because they aren't Ancient SOS), and you could pull it off in 100. And that's just from fishing.
Plus, only doing 30 would give you time to fish for the lobsters and crabs, as well as pull more MIBs. Not this is NOT taking into account gold from selling the gems (most fishers keep gems for imbuing these days), scrolls and the rest of the junk.
Each Sea Serpent pulled would get you 2-4 points more from the gold (plus several hundred points towards talismans at the Animal Trainer (scales) and Crafter (leather) library NPCs - amount varies depending on if you're human or otherwise, and whether or not you are using a harvester's blade to cut the corpses), with the chance of more MIBs, maps to donate to the Treasure Hunter, or fishing nets (which can get you more MIBs, maps, scales and leather).