quick question for the prop guru's

lonemust · Aug 26, 2010

How much of a differnce is there between a 14 1/2" and a 15" prop, both are 23" pitch, permformance wise. I have both and wondering which one would give better holeshot and over all performance. I have a 18' '70 starcraft w/ merc140 w/ mc1 o/d. quick response apprictiated thanx

usskydvr · Aug 26, 2010

Re: quick question for the prop guru's

Hard to answer because they will be different models. Performance should be close. As you have both ,do some of your own testing.
In very GENERAL terms the smaller dia should have better top end and the larger dia better hole shot.

lonemust · Aug 26, 2010

Re: quick question for the prop guru's

They both are Michigan props (smc)

lonemust · Jul 25, 2011

Re: quick question for the prop guru's

opps they are both mercuiser props, the one is a 14.5x23 and the other is a 15.25x23.. and both are 3 blade aluminum props

steelespike · Jul 25, 2011

Re: quick question for the prop guru's

Its been allmost a year and you haven't tried them yet???
While they are both Merc props they are obviously different models and very likely will have different performance. The larger diameter may have slightly lower rpm may have less venting problems.

lonemust · Jul 26, 2011

Re: quick question for the prop guru's

well i did try the 15.25x23 but it did me no good cause it has to be rehubbed.. and the both look like factory props. the numbers on both props are in the mercruiser manual i have, which is the factory service manual have both vol 1 and 2

SparkieBoat · Jul 26, 2011

Re: quick question for the prop guru's

generally speaking if everything about the prop is the same you will gain about 50-100 RPM per inch less in DIA. pitch and prop design effect it way more.

lonemust · Jul 26, 2011

Re: quick question for the prop guru's

ok so i wont see much of a difference if i have the 15.25x23 rehubbed and use it then.. didnt know if it would give me more speed being bigger in dia. or not over the smaller dia one

fishrdan · Jul 26, 2011

Re: quick question for the prop guru's

How many RPM's was the engine turning at WOT? 23P seems kind of steep for an 18' boat with a Mercruiser 140HP. I'd expect something more like a 19P Prop,,, maybe a 17 or 21 depending on load and what you are doing with the boat.

lonemust · Jul 27, 2011

Re: quick question for the prop guru's

the 3 of us wieght in at about 750 lbs.. had a small cooler with food and drink plus fishing gear. and a 15lb anchor.. the engine was turning 4400rpm at 42.8 mph

SparkieBoat · Jul 27, 2011

Re: quick question for the prop guru's

4400 rpm is a good range, sounds like it is propped right to me. you will probably see slightly slower top end with the bigger prop.

quick question for the prop guru's

Petty Officer 1st Class

Chief Petty Officer

Petty Officer 1st Class

Petty Officer 1st Class

Supreme Mariner

Petty Officer 1st Class

Captain

Petty Officer 1st Class

Admiral

Petty Officer 1st Class

Captain