spun hub?

Is there anyway to tell if our prop hub is spun without putting it in the water and running it? The lake is about an hour away, earmuffs do not work on our motor and we dont have any barrels big enough to fill and try. Can you tell by looking at it? I have been told that it should have a rubber piece between the prop and the hub, but it does not look like there is anything, just looks like metal against metal.
My husband thinks that if it is spun at all, that he would be able to turn it by hand. I disagree, told him that the motor has a lot more force and it may not slip unless it is being ran. Who is right?

Re: spun hub?

The best way to tell is by having it in the water. Draw a line across the hub and prop, then run it. When you pull it out if the line is no longer lined up, you have a spun hub. It is very hard to tell otherwise, but some of the experts on here may have an easier way. GL

Re: spun hub?

dk012377 said:

Who is right?

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You're right. Prop shops have the means to put enough torque on the prop to cause it to spin, but unless your husband has multi-horsepower arms, he can't. Don't know of any way to check besides putting it in the lake. Maybe someone else will happen by that knows of a technique.

Re: spun hub?

I once made a test fixture to check the torque required to spin it. Found out that the required torque chipped the blades, so that didn't work out too well. In fact, at the specified torque it often will badly distort or even break the stainless steel drive pin. That's why many props have that keyway in the hub to spin it in during manufacture. Consider this: A 35hp motor has the power of 35 horses pulling against that hub. Or a man with a long wrench handle.

As for construction, the shock hub is a piece of rubber bonded to the inner metal part that you see. That hub and rubber assembly is then pressed into the outer part of the prop, rotating it as it goes in. What happens when it is defective is that the rubber breaks it's bond loose from the metal hub part. Depending on the particular prop, you may not be able to see the rubber once it's in there, but it is.

Re: spun hub?

dk012377 said:

My husband thinks that . . . . . . . . I disagree, . . . . . . Who is right?

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The husband is always wrong!!