Propellers for 250 Explorer

[GOTSET2]

Hello, I have recently purchase an Aquasport 250 Explorer with a 225 Yamaha four stroke with 330 hours.  I keep camping gear on board and usually at least 3/4 full of gas.
My question is what RPM should my engine run to get best fuel economy?   It came with a aluminum 14.5 X 19 pitch prop.  I was getting about one MPG.  Put a new prop on this past week, SS Michigan Prop 15.5 X 17 pitch.  The boat seems to get on plane faster and engine does sound a little different.  The mechanic who installed it made a comment about three holes near the base of each blade.  Couldn't hear quite what he said but it appeared positive.  

Thanks to all you folks, I'm really pleased with this boat, looks good and enough room

Gordon

[wingtime]

I have a 225 Johnson carbureted  motor on my boat and a 17" pitch SS prop. I cruise my boat at bout 4600 RPM.  that gives me about a28-30 mph cruise and I burn 14-15 gallons an hour.  That translates to 2 MPG. That's with a hardtop and bottom paint.  I don't know what power setting your running but 1 MPG is terrible.  I'm sure that 19" aluminum prop didn't help.  The only way you can find the sweet spot of cruise speed and fuel burn is with some type of a fuel flow meter.  I'd highly recommend you look into installing a Flow-scan fuel flow gauge.  With today's fuel prices it will quickly pay for itself.  I have one on my boat and I'm amazed at how a small throttle, trim or trim tab adjustment can make a huge fuel savings.