Addition to Zeps VIL: Dont take all of Barts Quests - leave the last one. The three quests @ 35 gold comes to 105 - but then you have to log out before he gives them to you again.
Take his first two quests for 70 gold - and you can keep taking them without the logout (just cash in and then re-ask). You get 140 gold (for 2 trip sail) in the same time as 105 and having to Log Out/In
(Note: Same As that guy on Port Royal Beach with three quests - don't take his last one and you can repeat his first two as many times as you want).