Great question. I have a 150 yami 2 stroker and pushed my 60 gallon tank to the limit once. We made a 40 mile run one way, trolled for 5 hours and then back. I think it was about 120+ miles total. Ended the day with less than 10 gallons. My BH was a little puckered toward the end....passed right by breaking fish without stopping despite objections from the crew!
How many mpg do you get out of your motor? I get about 2.5 mpg and a little less in sloppy seas.....I know, 2.5 sux. I need Randlemanboater's 140 4 stroke - he gets 5mpg with it - nobody likes him on account of it. LOL