Props --- Diameter -vs- pitch?

[Dank]

I'm looking to replace my aluminum stock prop with a set of Hustler props. I'm currently running a 13.25 X 17, which will peak at about 5600 RPMs (Max should be 5500). I'm wanting to move to a 19" for cruising / speed, and a 15" for skiing or slower trolling, but they only have the 15" pitch in a 13.75 diameter. Is the extra half inch diameter going to offset the 2" lower pitch, making it behave like a 13.25 x 17? Any insight or experiences would be appreciated.

 

[DJ]

Re: Props --- Diameter -vs- pitch?

Dank,<br /><br />If you're running an OMC at 5600, I wouldn't worry about it.<br /><br />Typically, diameter has little to no effect on pitch. Diameter is important if you do not have enough room between the propshaft bullet and the cavitation plate.

 

[miloman]

Re: Props --- Diameter -vs- pitch?

dank I posted a thread called everything you ever wanted to know about propellers but was afraid to ask check it out I think it answers most questions

 

[Dank]

Re: Props --- Diameter -vs- pitch?

Thanks guys. I was thinking incorrectly that the larger surface area would reduce the slip to the point that it would cancel out the lower pitch. It sounds like y'all are in agreement that the difference between a 15" pitch at 13.25 diameter and a 15" pitch at 13.75 diameter would be very small. I'll measure to make sure, but I don't think the larger diameter will give me clearance trouble. BTW, I'm running a Yamaha 90.

 

[Boatist]

Re: Props --- Diameter -vs- pitch?

Dank<br />The extra 1/2 inch will make some difference but will not offset much of the difference the 2 inch less pitch will make.<br /><br />I agree with the 19 pitch for cruising, that should give you more top speed and better fuel mileage.<br /><br />I question if you really want to go to a 15 inch pitch for skiing. If your max RPM should be 5500 and you are already turning 5600, going to a 15 will raise RPM to 6000. When have a big skier up may be ok but you are going to have to watch your RPM's close to avoid doing damage to your engine when no skier and a light load.

 

[Dank]

Re: Props --- Diameter -vs- pitch?

I agree Boatist -- If the RPMs jump up to 5500 too fast, I'll probably move to a 17. I'm thinking that I'll lose a few RPMs with the cupped prop, plus i'll lose a couple hundred more by having the motor trimmed in while skiing, and will always have at least 2 people in the boat. I'll have to watch it more when I leave it on for trolling. Thanks for the advise.