Propeller balancing

[JohnnieMo]

Stupid question time:

So for years I have been dealing with vibrations in my boat when running at high ballast levels. After testing everything and aligning everything finally settled on a bad propeller.

A loaner 1235 proved this correct (thanks Killerbren) and I went out and bought a new propeller this year. However I put it on and although it was improved it didn’t match the flawless performance I got from Killer’s prop.

So the only difference between his and mine is I used a stubby key when I installed it.



So here is the stupid question: is the stubby key enough to throw off the balance of a propeller?

[Jetdriver]

I was wondering this the other day when I was swapping out a prop and noticed the key was kinda short. I’m not dealing with any vibrations or anything but it was an observation I made too. It’s such a small chunk of metal between the two and they sit so close to the rotational center of the shaft I wouldn’t think it’d make a difference but who knows.
What may make a difference is how far fore or aft the key ends up during the prop installation. Just a thought.

[chpthril]

Sounds like the prop(s) may not have been fully seated on the shaft.

[JohnnieMo]

Sounds like the prop(s) may not have been fully seated on the shaft.

Maybe. But I don't see how. There was like 5 of us there doing it. We can't all be that useless

I just had the prop rebalanced so let's see how it performs (with the larger key).

I do agree that you need to be careful that the prop isn't binding on the key.

If there is a problem to be had with propellers I will find it.

[UNSTUCK]

Just guessing here, but I would think a perfectly balanced prop somehow takes into account the key way in the prop. Once they machine the key way into it, the opposite side is now heavier and therefore out of balance. My thinking is that they know you will install a key that will make up that difference. So in my mine you would need to put in a key that is the same length as the prop key way. Installing one that is longer will make that side of the prop heavier and therefore out of balance. Will the extra weight of a longer key make a difference? I don't know. I know they sell and install .25 oz wheel weights for car tires and they spin MUCH slower than our props do.