New prop or can it be repaired?

[kevinstan]

Took the boat out for the first time this weekend. Everything was well... When taking the boat out I saw the result of me being too close to shore with the boat. Not sure if I started it over rocks or if it was from being moored at the shoreline against rocks, but the prop had some damage. No chunks missing or cracks on it, but the edges of the prop look a little chewed like someone tried sawing through concrete with it. Not horribly bad but noticeable to me. Is this something that can be filed with a metal file to fix? or do I need a new prop ?

 

[Texasmark]

A picture would help. Considerations are blade balance, uniformity in shape. Small dings not that big of a deal. Taking some diameter off the prop not that big of a deal either.

 

[kevinstan]

I am considering getting another one to have for if / when it needs to be replaced - and I am now stuck since they all have a different pitch to them. How would I be able to find what pitch of prop I would need? I have a 1985 mercruiser 3.0 - I think it is the alpha drive 1

 

[Texasmark]

If you are happy with your current prop and no numbers on the prop your local prop repair shop could tell you the pitch and may have a prop to suit you. Otherwise iboats sells them if you know what you want to purchase.

 

[steelespike]

What size/weight boat? Usually the pitch will appear near the base of the blades or under the prop nut.
What was your wot rpm and gps speed?

 

[tommr]

The mercury site has a prop finder app that helps you to find the right prop diameter and pitch.
I took a prop in a few weeks ago that had the blades bent back and they fixed it for $70.00
I don't think it is a bad idea to have a spare on board. And a wrench to remove and replace.

 

[kevinstan]

No Title

Updating now with images. Is this type of wear normal and ok to run the boat this way? Or is it done and I do in fact need to start shopping for a new one? Can this be filed down ?

 

[Texasmark]

Take a "Bastard" cut file and trim it up. Be on your way and don't worry about it.

 

[fhhuber]

Well...

It can be filed, but I'd want to check balance as I filed it.

The damage is pretty minor. Compared to some I've seen people running that is almost like new.

To balance reasonably well at home you need a shaft of some sort (pipe, dowel, section of broom handle...) that fits the prop hub and 2 level parallel edges, spaced apart a little more than prop length (front to rear). Put the shaft through the prop and set the shaft on the parallel edges. Heavy blade will rotate down.
The smoother and thinner the edges and harder, smoother plus better fitting the shaft, the more accurate this will be.

Its NOT as accurate as a prop shop will do it.

Number the blades with a sharpie or grease pencil... or crayon.

File a little more from the heavy blade.

If you think you are done, set each blade up and retest. When it will sit there with any blade up your pretty close. About as good as you'll do at home.

With the right setup, I can balance a common 1/4-20 nut. You don't need to be that accurate.

 

[Texasmark]

Well...

It can be filed, but I'd want to check balance as I filed it...................You don't need to be that accurate.

Well then for that very minor damage, why bother?

 

[fhhuber]

You want it as balanced as you can reasonably get it.

The simple balancing I described is not hard to do.

Filing the defects off the edges can prevent cracking of the blades which would lead to shedding maybe 1/4 to 1/2 a blade.

 

[fhhuber]

https://www.youtube.com/watch?v=rPxYBbqFDxE

Pro doing it with a balancing stand...


this will get it closer than the simple setup I described because of less friction

Then they might move it to a dynamic balancing rig.

 

[David Young]

If your top speed and rpm didn't change, i wouldn't worry about the light damage. If you notice something different than before the damage, i would order a new prop and keep your old one as a backup

 

[Texasmark]

I'm moving on down to the next listing on this one like I said above.