I buy gas on land and lug it down to the dock, Gas station is about 4 miles away..I can get close to 40 gallons per trip, buy used gas cans at every garage sale I see if they are in decent condition. One of the concerns I don't think any one mentioned here is Ethanol. Around here gas is soo expensive on the water I only buy it if I am out and about and running out of fuel...have not bought gas on the water in many years so I don't price it but it is usually .75 plus cents more on the water..It seems all the gas stations around here only have 91 with no ethanol. I have heard it will do bad things to gas hoses and carbs??? SO I don't take the chance of running that.
Takes me several trips to fill both boats usually keep them pretty full so I don't have to make the trips all at once.