The Right Prop for the job

[kapaafire]

Haven't posted in awhile cause.....I conceded and purchased an new Evinrude E-Tech 115 hp long shaft.

At full throttle I am only able to achieve approx. 5000 rpms. The ideal range should be between 5500-6000 rpms.

The current prop is an aluminum 3 blade prop that has 14.8 X 17 stamped on the side. My boat is a 17' cutty cabin "current Line," that weighs approx. 3,000 lbs dry weight. I also load up 60 gallons fuel, 3-50lbs bags of ice and have 2 adults/ 1 child, and 8 hp kicker as added weight. I burn approx. 4 gallons an hour trolling at 8 knots (3,000 rpms !!).

Any suggestions on the proper prop pitch, 3 vs. 4 blade, stainless vs. aluminum???

Any suggestions would be appreciated.

Thank You

 

[JB]

Re: The Right Prop for the job

Moving to Prop Forum.

 

[WillyBWright]

Re: The Right Prop for the job

What is the maximum horsepower rating for the boat? With the numbers you posted, you might have to drop down to a 13p, but I'd certainly try a 15 first. That sounds like too little motor for a too much overloaded boat. Normally, a 115 on a 17 footer should be plenty and I would consider a 17p prop a power prop.

Are you boating at a high elevation?

 

[kapaafire]

Re: The Right Prop for the job

Thanks for the response,

Not at elevation. At sea level in Hawaii. I usually use the boat for trolling and the equipment is standard for over here. The boat is called a 17' current line, but it actually closer to a 19' boat. Very heavy glass w/ a V-hull to deal w/ the chop and wind swells here.

Would you have any suggestions for:

Pitch?
stainless Vs. Aluminum?
3 vs. 4 blades?


Thanks for the interest

 

[propper_advice]

Re: The Right Prop for the job

I would recommend staying with the three blade because your not pulling anybody. you'll need to go down in pitch to gain more rpms getting you in the upper part of your rev range. typically when you change your pitch by two you gain or lose 400 rpms depending whether it's up or down of course. So your in a 17 pitch, you want to drop your pitch to increase those rpms from 5000 into your rev range which you said was between 5500 and 6000. With your rev range you want to drop your pitch by four from a 17 to a 13 to gain 800 more rpms giving you 5800 rpms at wide open. check out all the different sized props for your motor at www.piranha.com to see if a composite propeller meets your needs.

--Nick