can prop hub slip and still sorts work?

[Georgesalmon]

I have a 115hp merc and while trying to find the correct pitch prop I tried an old prop that came with the boat. While testing it the first time I gunned the motor it over revved and felt like ventilation. Slowed down and tried again and boat took off. Problem is that I got way more rpm than I should have. Going from a 19p 4800rpm to this 17p I got 5600rpm. Way to much for a 2" pitch change. When I took the prop off I noticed that the rubber I can see is kinda burned looking (course I never looked at it before I ran it). Can a prop slip its hub and still kinda work but slipping in the hub all the time? This prop is probably a 1979 vintage.

 

[robert graham]

Re: can prop hub slip and still sorts work?

It can turn the prop, but start slipping at a certain torque/throttle setting...and it'll just get worse...need to rebuild or replace that prop!

 

[Georgesalmon]

Re: can prop hub slip and still sorts work?

Thank you. I think this one is destined for the scrap Aluminum pile. It dosen't have any cupping at all and thart means to me very old and not worth a rebuild.

 

[etracer68]

Re: can prop hub slip and still sorts work?

You say it doesnt have cupping, That alone will change rpm. Differante style props, may turn more or less rpm, not just pitch alone. Rule of thumb is 200rpm per 1 inch pitch, but that would be if the same style prop also.

 

[Home Cookin']

Re: can prop hub slip and still sorts work?

yes--and that burned look is an indication that the prop is spun, too.

I've even had shear pin props work at low speed with a broken pin

 

[Georgesalmon]

Re: can prop hub slip and still sorts work?

Got lucky. My son found two props for me to try. A 15p 4-blade (the new merc one) and a 17p 3-blade at work. And one flo torq hub kit to swap between the two props. Can't keep em but should get most of the info I need. Now that you mention it I had the same shear pin problem many years ago and it got me home (barely). I can probably take the shear pins out of my tackle box now too.