Question To Prop Experts

Thornback · February 05, 2017, 03:18:08 PM

I have noticed a couple of times my RPM was more than usual for my MPH. Plus I could tell by the sound my Merc 60 EFI 4-stroke was revving. Is it possible a prop hub can slightly slip at times and not at other times? Or did I just have some trash on the prop?

Princeton_Man · February 05, 2017, 03:49:53 PM

Could be either one. I've run through weed beds and experienced similar symptoms. I'd pull the pro and check behind it. Before you put the prop back on, use a marker or a file to make a mark directly across the back of the back of the prop, hub and bushing. Take it out for a run, then pull the prop when you return and check to see if the line is still lined up. If it's slipping, it won't line up.

Bud Kennedy · February 05, 2017, 03:50:30 PM

I would not be surprised if you are not experiencing some level of prop blow out. This would depend upon what your set up is in relation to prop to pad. Second question does this happen during turns? I would doubt that you have spun a hub because you would loose all ability to turn the prop and it would not be an intermittent thing.

Thornback · February 06, 2017, 06:45:34 AM

Thanks guys for the quick info. My original aluminum prop has a few nicks so I think I'll replace it and keep the old one in the boat for a spare should I have a prop accident while out fishing.

Princeton_Man · February 06, 2017, 07:20:38 AM

Quote from: Thornback on February 06, 2017, 06:45:34 AM
Thanks guys for the quick info. My original aluminum prop has a few nicks so I think I'll replace it and keep the old one in the boat for a spare should I have a prop accident while out fishing.

Didn't know about the nicks. If they are sizeable enough, they can cause slippage. At a high enough speed nicks create bubbles/cavitation.

I've also read that aluminum props will flex and effectively have a change in pitch during hole shots and at WOT rpm.

Thornback · February 07, 2017, 01:58:00 PM

I purchased a new prop this morning and the guy at the boat shop said my old prop did not appear to have slipped on the hub at any time, but it had some serious nicks on all three blades. He also said if you do spin the hub you should be able to move about on idle. I now have a spare prop, pull bar, and 15/16" socket on board. And as PM suggested I marked the old prop and hub with matching marks. Here's hoping I never need the old one

Princeton_Man · February 07, 2017, 06:26:23 PM

Sounds like you're in good shape now.

Thornback · February 10, 2017, 11:35:44 AM

Tried out the new prop this morning. I also replaced both the male and female gas line snap-in connectors along with new gas line and primer bulb. I was sucking air with the old snap-in connector and the gas line was deteriorating on the inside. Motor ran great. Boat performed great.

Princeton_Man · February 10, 2017, 11:47:14 AM

Quote from: Thornback on February 10, 2017, 11:35:44 AM
Tried out the new prop this morning. I also replaced both the male and female gas line snap-in connectors along with new gas line and primer bulb. I was sucking air with the old snap-in connector and the gas line was deteriorating on the inside. Motor ran great. Boat performed great.

Awesome!