What is the GEAR RATIO of 55EL78S
Of all the outboard motor specs, the actual propeller REVs seem most important if you are evaluating props.
My motor is supposed to develop 55 HP at 5500 Engine RPM, but I don't really know what's happening until I know the gear ratio of the drive.
If it's 2:1 then I should be making 2750 turns and a 15 pitch prop should get me to well above 30 miles per hour. 37.6 miles an hour in a perfect fluid with no slip.
But the boat is doing about 25-30 MPH (by GPS) depending on load (300-700lbs) and fuel type ( Regular/off road regular)
So it's slipping between 20-30% if it's a 2:1 ratio
If it's a 2.2 : 1 ratio the theoretical top with no slip is more like 34.2 MPH and the actual performance is indicating between 12 and 25% slip.
Of all the outboard motor specs, the actual propeller REVs seem most important if you are evaluating props.
My motor is supposed to develop 55 HP at 5500 Engine RPM, but I don't really know what's happening until I know the gear ratio of the drive.
If it's 2:1 then I should be making 2750 turns and a 15 pitch prop should get me to well above 30 miles per hour. 37.6 miles an hour in a perfect fluid with no slip.
But the boat is doing about 25-30 MPH (by GPS) depending on load (300-700lbs) and fuel type ( Regular/off road regular)
So it's slipping between 20-30% if it's a 2:1 ratio
If it's a 2.2 : 1 ratio the theoretical top with no slip is more like 34.2 MPH and the actual performance is indicating between 12 and 25% slip.