Is the prop lock washer neccessary?

[Dmoadus]

Bought a new prop from iboats this week and when I went to install it found that it completely covered the splined area leaving none protruding for the retaining washer to grab. I called the folks at iboats who were very helpful by the way, but couldn't resolve my problem. They checked a number of different ways to see if the prop was the correct one for my boat and said that it is the right one. They said they had no idea why it covered more of the splined shaft than my old prop did. They said they would be happy to have it returned but wouldn't know what to exchange it with.

Putting the prop back on along with the spacer that was supposed to grip the splines but doesn't, I realized that the nut is a locknut, so I just cranked it tight without using the locking tab washer. It seems to me that being that the prop is splined to the shaft, that the only thing that could cause the nut to come loose would be the inertia of the nut itself, as the prop can not move. I can not imagine that it could generate the kind of inertia to overcome the grip of the lock nut so I am going to run the boat without the locking tabbed washer.

Being I'm kind of new to boating I'd like to hear from some of the experts as to whether or not they think I will have problem. I will keep my old prop with me as a spare just in case. What say you?

 

[craze1cars]

Re: Is the prop lock washer neccessary?

Year/make/model of motor? Pic of your current install? Anything more would help...have no idea what you're asking about here...

Frankly it would really bother me to not have a lock washer in place, if whatever you have is designed for one...

 

[Jerryh3]

Re: Is the prop lock washer neccessary?

Is the thrust washer on the right way?

 

[Dmoadus]

Re: Is the prop lock washer neccessary?

The boat is a 79 Arrowglass Stingray with a Mercruiser 470 motor and a Alpha One sterndrive. I'll try to clarify a little. After the prop goes on there is a retainer that has splines on the ID and notches on the perimeter where the locking washer's tabs are bent into. When the prop is fully seated onto the splined shaft, a little of the splines should still be exposed for the retainer to grip. Without the splines, the retainer will just spin with the nut as you tighten it. You could bend down the lockwasher's tabs if you wanted to but you would still be able to loosen the nut.

I'm new to the boating scene after spending years building and flying ultralight airplanes. As you could imagine having a prop come loose on an airplane presents a more serious problem, so I hope you will understand my willingness to take somewhat of a gamble that the lock nut alone will be enough to hold the prop on. I figure the worse that can happen is that I lose it in the lake and have to use my spare. If my description isn't adequate, I'll try to take a few pics.

 

[Dmoadus]

Re: Is the prop lock washer neccessary?

By the way. I'm certain that there is nothing under the prop that might be holding it up, and there is only one way that the thrust washer goes on that will allow the lock washer's tabs to be bent down.

 

[willamettejeff]

Re: Is the prop lock washer neccessary?

By the way. I'm certain that there is nothing under the prop that might be holding it up, and there is only one way that the thrust washer goes on that will allow the lock washer's tabs to be bent down.

I believe the thrust washer is the one that goes on the shaft before the prop and is then between the prop and the gear housing. It has a larger diameter on one side and a smaller tapered one on the other. If on backwards, it will not allow the prop to seat all the way onto the shaft. The smaller diameter side goes towards the prop.

-- Jeff

 

[craze1cars]

Re: Is the prop lock washer neccessary?

Sounds like it doesn't fit quite right...

Also sounds like you don't care too much and are willing to risk losing your prop....

You understand the risk. So it's your call entirely. If torqued down tightly, it'll probably stay there. Might not.

FWIW, if it ever does come off, it'll only happen when you are in reverse gear...that's the only time the retaining nut is actually doing anything. When in forward gear, water pressure will hold it on tight as can be at all speeds....

 

[Dmoadus]

Re: Is the prop lock washer neccessary?

I believe the thrust washer is the one that goes on the shaft before the prop and is then between the prop and the gear housing. It has a larger diameter on one side and a smaller tapered one on the other. If on backwards, it will not allow the prop to seat all the way onto the shaft. The smaller diameter side goes towards the prop.

-- Jeff

There is nothing between the prop and the gear housing....No washers or spacers, but thanks for all the advice anyway.

 

[craze1cars]

Re: Is the prop lock washer neccessary?

There is nothing between the prop and the gear housing....No washers or spacers, but thanks for all the advice anyway.

Correct...there is nothing between prop and gear housing that you can see while prop is installed, but he was not talking about that location...he's talking about thrust washers....fully hidden unless prop is removed. A discussion here with pics of a few:
http://www.mercstuff.com/thrustwashers.htm

I am VERY certain your prop has been installed with a thrust washer first, then the prop....in fact you mentioned that you have one, as all Alpha 1's have thrust washers. Without a thrust washer, the prop would simply drag tight against the gearcase and would not turn...

I will now suspect it's a bit too thick for the prop you installed.

Refer back to that link above...the older Alphas (like yours) run thick thrust washers. Newer style prop on an old Alpha will often require a thinner thrust washer. I'm willing to bet that there is a good chance that your new modern prop, on your old outdrive, needs a thinner thrust washer than you currently have installed...and like magic, with a thinner washer behind the prop, your locking tabs would reach the splines....

Again, a photo or two would be worth 10,000 words here. I think it's hard for people (myself included) to picture in their minds what you are trying to explain. Are you able to post up a photo?

 

[Dmoadus]

Re: Is the prop lock washer neccessary?

Thank you for replying and posting a site with pictures. I haven't had the time but tomorrow I should be able to pull the prop to look for any thrust washers. I just don't remember seeing anything that looked like it might be removable. If I don't find anything I'll post a picture.

 

[Rocky_Road]

Re: Is the prop lock washer neccessary?

Make sure that you don't have two thrust hubs before the prop...the old one may have stayed on the shaft, and the new prop may have its own.

 

[GA_Boater]

Re: Is the prop lock washer neccessary?

I think Rocky just asked the $64 question ^^^^^

 

[Dmoadus]

Re: Is the prop lock washer neccessary?

Thanks again for all the good advice. I did solve my problem. I was almost convinced that there was not a thrust washer on the shaft before my propeller. So I pulled the prop again and it looked just like it butted up against an aluminum flange. I got to thinking that that couldn't be because the prop rotated and this part looked to be part of the drive's housing. I took a claw hammer and pryed a little under this flange and it moved so I pryed the other side and sure enough it slid right off the shaft. I had another prop that came with the boat but it was broken, but in the box was a thrust washer that was thinner than the original equipment one. I put it on before the prop and sure enough the shaft splines protruded enough to be gripped by the spline washer. So now I'm legit. But I have to say, I am convinced that since the prop was splined to the shaft one could run without the locking tabbed washer and never have a problem as long as your prop nut is of the nylon locking type. I ran mine like that without any problems, though it was only a week or two. None the less, I appreciate all the help.