Loss of forward thrust

[Jkrimmer]

Hi I have a Mercury 50 4 cylinder 2 stroke circa 1972. The problem I have is that on low revs all seems well but on acceleration I lose forward momentum although the revs increase. I have take prop of which is the old type with the fixed rubber hub. Looking at the inside of the prop the teeth on the front look reasonable but on the back the teeth have go completely. Is this because it's tapered or because it's worn out. I am assuming it's worth out and is slipping. Oh don't know if this detail is of an help but it was remarkably easy to remove.

Am I right in my assumption that replacing the prop will solve my problem or could there be anouther reason.

cheers
keith

 

[haventaclue]

I think your prop has spun a hub.You will see splines on one end only,the spline are on the rear end.

 

[Jkrimmer]

I think your prop has spun a hub.You will see splines on one end only,the spline are on the rear end.

Hi thanks for answer but do you mean that a new prop will fix problem or potentially is there something else that could cause this propblem
thank
keith

 

[galamb]

He means that the hub in your prop is no longer "stuck" to the prop.

A prop is two pieces - the hub, which is surrounded by rubber and then pressed into the propeller itself. It's designed that way so if you hit a rock or something solid that the rubber will let go instead of chewing up your gears (at least that is the design).

Over time the rubber wears out and the prop starts "slipping" on the hub.

When that happens you can 1) buy a whole new prop or 2) take your prop to a "prop shop" and they can replace the hub (cheaper than a new prop and the way to go unless your prop blades are also damaged).

 

[Jkrimmer]

Hey thanks for that sounds good advise
cheers

 

[haventaclue]

that the rubber will let go instead of chewing up your gears (at least that is the design).

Doesn't always happen Hit a sand bank,hub didn't let go,tore two teeth reverse gear and one from the pinion.And the damm depth gauge was showing 11'