RPM Too High - Low MPH

**whiskey phish** · 10-10-2014, 02:57 AM

Hey guys I just got a new to me rig, 175 Alumacraft Dominator deep v with a 115 etec. The prop is 14 3/4x 17p. I'm fairly new to boats and don't have experience, especially in this kind of boat but to me it seems to get up great. The problem I'm concerned with is that it is over 6000 rpm and it feels like it has more throttle left to go. On plane and trimmed it will barely hit 22 mph @ 5500 rpm with no load and two average people. The specs show tests of 42 mph with an 18p stainless prop. I'm not looking to go 40+ necessarily but I'm worried that there is something wrong. I have done some reading but can't figure it out. It is mounted in the second from the top hole, the other thing I checked was it looks like the prop is seated in the housing properly and with the engine off and in gear will not turn (thought it might be slipping). I'm scared of over revving and doing damage, and would like to see better performance. Will the motor shut itself down before it red lines? What do you guys think I am looking at?

**Rees Guide** · 10-10-2014, 06:33 AM

Sounds like the prop is spun, carry it to a shop and see what they say. It has a press in clutch that has most likely gotten weak.

**midcarolina** · 10-10-2014, 07:18 AM

Make a mark with a permanent marker across the hub and prop.......... take it out for a ride then check marks, if marks have moved spun hub if not it's other issue's
wot rpm is 5500-6000.......... if you perform the marker test and it passes, then I would try a different prop especially since you say you hit 6k with more throttle to go..............

You also may want to verify the tach is accurate and not reading high.

**dfar** · 10-10-2014, 01:18 PM

Like was said prop hub may be spun. 6000 rpm is max rpm motor should be ran. At that RPM you should be going 40+ mph.
If you are any where close to Olathe Ks take it to Midwest Propeller they can repair it and do great work.

**whiskey phish** · 10-10-2014, 05:18 PM

Thanks for the great feedback guys! What kind of money am I looking at ballpark? If the weather would cooperate I'll take it out this weekend and run the marker test on it. Assuming that's what it is, does a shop need to repair or is it just pull the prop and put new parts on?

**Cray** · 10-10-2014, 05:24 PM

Most of the time it takes a prop shop. That rubber hub is pressed in with a hydraulic press. Plus they should have the right one for your prop.

If it is not spun I'm thinking that 17 is pretty small for that setup. I'm thinking that a 18 or 19 pitch would be more like what you need with that 115.

**golfprocrappieman** · 10-13-2014, 03:34 PM

I'm 100% with Cray....Have a 19 pitch on my seapro with a 115 ...It's great

Originally Posted by cray

Most of the time it takes a prop shop. That rubber hub is pressed in with a hydraulic press. Plus they should have the right one for your prop.

If it is not spun I'm thinking that 17 is pretty small for that setup. I'm thinking that a 18 or 19 pitch would be more like what you need with that 115.

**whiskey phish** · 10-16-2014, 01:36 PM

Just picked it up from the shop and the tach was off by 1000. Back in business!

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