small ding on the flange

[bones1918]

i hit a log the other day doing about 3 or 4 knots, i pulled the engine up, did a quick visual inspection, and it seemed fine, so i kept on going. spent the rest of that day at low speed.<br /><br />a couple days later, i went out and intended to go full speed, wich is usually around 31 knots on a flat day or 29 if its a little choppy. i coudlnt get above 19.5. the RPM's seemed to be the same (no tach) and the water was glassy, so im thinking it must be the prop. i did a better inspection, and noticed theres an ding on the flange of the body of the propeller. its not huge.. the out of shape spot seems about the size of a quarter. The ding is on the flange on aft end of the cylinder of the shaft. could that little ding really be causing me a 30% loss in efficinecy?

 

[Seasport]

Re: small ding on the flange

Quite possibly. It will also cause your prop to be out of balance which will set up a nasty vibration in your motor. This could cause premature bearing failure etc. Best to get it fixed.

 

[ivar]

Re: small ding on the flange

Could also be that your hub is slipping, a minor ding should not have that much impact.

 

[imported_Curmudgeon]

Re: small ding on the flange

Could also be that your hub is slipping ..<br /><br />If he's getting 19 mph with near normal RPMs, it ain't the hub slipping! A hub slip in his situation would be RPMs screaming and speed almost non-existent.

 

[ivar]

Re: small ding on the flange

O.C, <br />normally it will do as you describe, but I've also seen otherwise.

 

[bones1918]

Re: small ding on the flange

I'll pull it out of the water today and pull the prop off and really examine it up close. how can i check for hub slipage? it's a 1989 evinrude 70 hp, btw

 

[PuddleJumper]

Re: small ding on the flange

Mark the prop with crayon or indelible marker across hub and prop body. Run boat in water at WOT then check the marks.

 

[umblecumbuz]

Re: small ding on the flange

I've got a feeling that there's some other reason for your loss of speed. A 'small ding' in a prop wouldn't do that. <br /><br />I'm no prop expert, but I've run props that were really only fit for junk, and they've still given me close to maximum.<br /><br />And as Old Curmudgeon says, a spun hub would show itself by a howling motor and very slow speed.