1980 Chris Craft Catalina 251 - More Gas Related Questions ....any help is appreciated....

Well, my previous post from a few months ago is still the last post so not sure how active this forum is but I did get some great ideas from my last post. I'm still messing with the gas tank replacement but on the home stretch or I hope. I had a question regarding gas consumption or how far do you think I can go with "X" amount of gas and being conservative, taking it slow? I did some research and I have found mixed feedback on what to expect. I am considering moving my boat about 75 miles to the south and there are not too many places to stop and fuel up. I will have a 70 gallon tank, have a 305 oritional engine, and feel I should have enough if I keep the speed below 10 kts. Any feedback from similar boat owners? I found a chart, at 2400 rpm's, running below 10kts, I can expect to burn around 6.5 gallons per hour. Anyone have experience and can confirm if this is on target?
Thank you.

Good luck.

Sounds a little high to me. I have twin 327F's in a 1966 CC Cavalier and I burn about 8 gph cruising at 8-10 mph. The best thing to do is fill up your tank, drive the boat a known distance of at least 25 miles at a fairly consistant RPM and then top off the tank again. If you also track engine hours you will be able to calculate hrs/gal and mi/gal.

Dave