Prop Help Needed

[gio908]

I would appreciate some help with choosing the right prop for my motor. The boat is a 16' Dusky 16R Skiff with a 1998 50HP Evinrude (my first boat). The prop currently on the motor is 13" diameter x 11" pitch, and with it I'm getting 25MPH WOT and only 4100 rpm's (assuming my tach is accurate). The dealer suggests that I fit it with a prop that will put me between 4500 - 5500 rpm's. I'm guessing that I need to go down in diameter, since I can't really go down in pitch because 11" is about as low as they get for this size motor. How much does diameter effect rpm's? Any suggestions?

 

[DJ]

Re: Prop Help Needed

gio908,<br /><br />Something doesn't sound right here.<br /><br />The diameter change will really not help.<br /><br />I am suspecting that the Dusky is a VERY heavy boat and you are underpowered.

 

[gio908]

Re: Prop Help Needed

The hull is only 650 lbs, and the maximum HP rating is 50HP. Could it be that my tach is inaccurate or on the wrong setting?

 

[DJ]

Re: Prop Help Needed

With that, I would say that there is a tach. problem.

 

[gio908]

Re: Prop Help Needed

How do I verify that the tachometer is reading correctly?

 

[DJ]

Re: Prop Help Needed

The easiest way would be to check it against a service facilities shop tach.

 

[phatmanmike]

Re: Prop Help Needed

hi, i have a 650 pound center console 16 footer with a 50hp johnson, i had a 13 pitch prop, but was too slow, so switched to a 15 pitch and now boat goes 25-30mph depending on conditions and gear and such. others i have seen have 17pitch, but yours and mine are too heavy for that, try mooving up in pitch.. i have a used hustler 13 pitch that would fit yours perfectly, used for about 3 hours between 2 diff days, then my engine puked parts all over the place, so it sits on a shelf....<br /><br />going down in pitch will make the boat slower, if you want faster, you need more pitch , and check that tach....<br /><br />email me if i can help you<br /><br />mikey<br /><br />phatmanmike@yahoo.com

 

[walleyehed]

Re: Prop Help Needed

Don't change ANYTHING until you can verify the RPM you are turning now.<br />You NEED that baseline to make any knowledgable adjustments.

 

[gio908]

Re: Prop Help Needed

I think that was good advice... not to change anything until I have the tach verified. How much should this service cost me? The service shop around here charges $85/hour, and I would hate to pay for even one hour of labor for something like this.<br /><br />Mike,<br /><br />I might be interested in your prop? Is it aluminum or stainless? What's the diameter? Let me check my tach, and I'll get back to you if it turns out that I need a 13 pitch prop. I'm guessing that I'm going to need between a 13 and 15 pitch.<br /><br />thanks<br /><br />Giovanni

 

[rickdb1boat]

Re: Prop Help Needed

If your're real friendly and maybe a little deposit, they will let you borrow one to verify the reading against yours.