Prop change... What to expect?

[ronward]

I believe details will likely be irrelevant to this question because I have no tach or speed numbers to give. I will give as much detail about the boat as I can. It's a 1970 Starcraft V160. 16' glass semi deep-V, 85 hp Johnson. No clue as to weight. I have a 13 1/4x17 ss on it right now. It does good enough. What I am trying to find out is what would likely happen if I switched to my other prop, a ss 13x19? Both props are Michigan and both have about the same amount of cup to the blades. Holeshot is not a big issue but which would give me a little more speed? I plan to install a tach soon to get accurate numbers. But can someone give me an idea of which prop would be better for what I want? Better fuel consumption also?

 

[MikDee]

19" More speed less torque, maybe better gas mileage?

 

[jestor68]

How bout 42 mph @ 5000 rpm? From the Mercury prop selector with a 500 pound load and 18 gal of gas.

Hole shot will be a little slower than the 17, which should turn about 5400 rpm.

The dry weight of your boat/motor is listed as 1200 pounds.

 

[ronward]

13x19 is a little dinged up, not real bad. Other is perfect. Any significant loss if it's dinged up? I dressed it up but there is a little material loss on one blade, not much at all. Will the 13 1/4x17 perform better since it is flawless or is the gain from the 13x19 going to overcome the little damage it has?

 

[jestor68]

I guess you'll need to try it to find out.

 

[doyall]

... But can someone give me an idea of which prop would be better for what I want?...

Since you didn't state what you wanted, it is quite difficult to say if the change will achieve it.

I can't help but think that any differences will be imperceptible without some form of measurement, but in any case the differences will be inconsequential.