Do propellers wear out?
 

I just lost 4" of the tip on a 6 blade RH 20X32 SS Rolla propeller. I didn't hit anything. The boat is in the salt water all the time. The propeller is 3 years old and has about 500 hrs use or about 17,000 miles. I have been told that this can happen to SS props. Do props wear out like tires? Will this happen to my other 2 props? Is there anything that I can do to help prevent this from happening? I'm waiting for a quote for price and delivery time for a new prop now but it may take 10 weeks to get one.
Ken

Re: Do propellers wear out?
 

Metal fatigue can be an issue particularly with labbed props

Re: Do propellers wear out?
 

The simple answer, Yes props wear out. They are thin and undergo severe cyclical loading and like any other metal they will fail through fatigue. Lab-finished props are especially susceptible because they are further thinned down from stock.

Dents, dings and scratches will hasten the process by providing areas of stress risers.

And since most props are cast there's always the possibility of embedded imperfections like inclusions and/or voids and those areas will fail first.

Re: Do propellers wear out?
 

I believe racers in Supercat only get a few races out of a set of props.

I also believe it takes big HP to wear em out. I don't think a 50hp OB will ever wear a prop out, even if it's aluminum.

Re: Do propellers wear out?
 

Cig Daze very nice! However, I would add that you may want to take a look at your set-up and have your props inspected to get a professional opinion, as to the failure and possibly look for ways to improve the set-up and/or your propellers. You will have to match the new propeller, to your intact propeller. As you will now have a new propeller made at a different time by a different technician. This way at least you know you have done everything that you can to aviod future failures that are set-up related, possilbly. Food for thought.

Julie

Re: Do propellers wear out?
 

Thanks for all the advice. The drives are Arneson ASD8 on a Fountain 48 this is their standard setup. I would like to prevent this prop failure in the future. I'm disapointed that I have to wait 10 weeks to get another prop. I can only imagine what it will cost. Ken

Re: Do propellers wear out?
 

Thanks Julie. :cool:

Re: Do propellers wear out?
 

I just met I guy with cryogenic freezer he use it to treat just about anything they can get in them (connecting rods, ball joints, cutting tools), would that process benefit a prop?

Re: Do propellers wear out?
 

Very interesting. I looked it up on the web and called one these services. They told me they could use this process on a new prop to relieve stress but on the used props they have to be good condition. He suggested that I have the other 2 props magnaflexed to see if there are any cracks and if none he could do the service. From what I read the -300 Deg deep freeze realigns the molecules to relieve stress. The company I called was in IL named "300 Deg. Below" 217-423-3070.It would cost about $75 per prop. Has anyone used this process before? Are there any of these services in S Florida? It's been 2 days now and still no quote for delivery and price for my new prop. Ken

Re: Do propellers wear out?
 

I did it with my baseball and softball aluminum bats. The freeze eliminates weak spots....

Re: Do propellers wear out?
 

Yes, cryo treatments work well on stainless steels. It relieves stress, and can harden and toughen the metal beyond an ordinary heat treatment.

Re: Do propellers wear out?
 

Chryo treatment is something that needs to be done by someone who has the right equipment and knowledge of the particular material that's being treated.

We had some props chryo treated by a local guy and the props lost all the hardening and they bent like they were made of aluminum.

Chryo treatment is frequently part of a hardening process. A typical hardening process may entail annealing, chryo, and precipitation hardening. There are very specific guidelines to these hardening treatments which have strict temperature control and time parameters.

I have learned some of these guys have a bottle of liquid nitrogen in the basement and will tell you it's the answer to all metal problems.

Whoever you work with, make sure they are familiar with PH (precipitate hardening) stainless steels ie; 15-5, 17-4, 13-8, etc. They should be able to give you information regarding the advantages of their treatment.

Kennorth, your boat has either the 440 or 480 Yanmars, right? With those motors and the drives you have prop breakage should not be an issue. You need to check the props from time to time for nicks. If you find some they needs to be addressed, especially on a surface drive.

Re: Do propellers wear out?
 

Who are you getting the new propeller though?

Re: Do propellers wear out?
 

Good response...............................
Jr.

Re: Do propellers wear out?
 

I called Fountain but they don't have any in stock and would have to order it from the Rolla factory. You would think that they would keep one in stock now that they have produced over 50 of these 48' cruisers. I also call Mark Wilson on Tue. and I'm waiting to hear back from him. A prop guy yesterday told me that it may take 18 weeks to get one made. Looks like I may not be boating up to 4 months. Is there another prop that will fit? Are there outlets where you can rent a prop from someone who's boat is laid up for the winter? Ken

Re: Do propellers wear out?
 

We chucked a Merc Cleaver blade in our Cat @ over 100mph this past summer, thought we blew another #6 drive.
Checked our other prop and she was also ready to start chucking blades, very small cracks at the base of blade to hub,metal fatigue, we never hit a thing or even dinged those props.
Yes they definitely do where out!

Re: Do propellers wear out?
 

I've seen props go on unlimited hydroplanes. Not pretty. Keep in mind they turn (IIRC) almost 3 times the speed of an offshore's props.

I think the money teams only use them for a couple races anyway.

Re: Do propellers wear out?
 

Kennorth, Many props will fit that boat. Finding one with the diameter will be the challenge.

It's also possible to repair the prop. In a situation where part of the blade is thrown, like yours, we don't normally recommend repairing the props, however, considering the cost of the new prop it may be an option to repair the prop you have. It would be expensive as it would require a full heat treatment after repair but it would still cost a fraction of a new one.

We have made repairs on props that normally shouldn't be repaired but with the proper treatment after repair sometimes the prop will live a happy life. Repairing the prop you have may be an option, it's something we would have to look at prior to making a final decision.

Re: Do propellers wear out?
 

Give me a call, I can give you a lead for a propeller.

415-485-0788