Cleaning Props out of the water

Hi there,

We have two 30" propellers on our Europa 53 that are out of the water. I want to apply PropSpeed to them in the spring. Several yeas ago I power sanded my 25" props from my Mainship. That process seemed like it took forever - over 8 hours per prop or longer.

I'm researching into whether walnut shell blasting the props would be a better method. I can purchase a 20# blaster from Harbor Freight for $80, plus the shells.

Does anyone have any advice on the best and quickest way to shine up the propellers?

Thanks - JimL

I had the props rebuilt on our last boat. The PO had many thick layers of paint on them. The prop shop put them in a sand blasting booth and cleaned them up in a few minutes. Don’t know what media they were using but it went quickly.

My favorite boatyard just sand blasts it on the shaft. It's quick and does a thorough job. Don't know what grit sand they are using.

If you're going to do it yourself there are a couple of things to avoid. I wouldn't want to sand blast the inside of the taper, just stick a rag in the hole. Second, don't get heavy handed on the leading edges of the blades. Tapering them too much makes them sing. It's a harmonic resonance that travels into the boat through the shaft at certain RPM ranges. It's annoying as crap, and can't be doing any part of the drive train any good. The cure is to run a file on the leading edges to blunt them slightly.

Ted

Ted,

Thanks for the tip on dulling the leading edge. Can you elaborate further? Maybe that's the cause of my weird noise in this thread:

https://www.trawlerforum.com/forums/s15/weird-screeching-noise-58576.html

Jim

jimL said:

Ted,

Thanks for the tip on dulling the leading edge. Can you elaborate further? Maybe that's the cause of my weird noise in this thread:

https://www.trawlerforum.com/forums/s15/weird-screeching-noise-58576.html

Jim

Click to expand...

I don't think that's what the noise you posted about was.

The "singing" usually occurs over an RPM range and always repeats in that range. I only have experience with it in a single engine vessel, and have no idea if and how it may be different in a twin engine boat. While I know it happens in low pitched props, I haven't heard about it happening in normal or steeply pitched props.

It's happened twice to me with my current prop. Once in North Carolina when I hit something and the prop shop feathered the edge. My regular prop guy explained to me what they had done, and it was a pretty easy fix. The other time was from a novice in the yard spending too much time with the sand blaster on the leading edge. Now I examine the leading edges and touch them up with a flat file as needed.

Ted

jimL said:

Hi there,

We have two 30" propellers on our Europa 53 that are out of the water. I want to apply PropSpeed to them in the spring. Several yeas ago I power sanded my 25" props from my Mainship. That process seemed like it took forever - over 8 hours per prop or longer.

Click to expand...

Glad your not working for me

Our 52 inch prop, Kortz nozzle and barn door sized rudder take about 3 hours total using a 100mm angle grinder, 60 grit discs and a delicate touch when getting to the bronze.

Use a StripIt style disc on a 4" angle grinder. Save yourself hours, but wear a mask and contain the dust!
https://www.tradetools.com/tomcat-125mm-strip-it-disc-tsd125

Insequent said:

Use a StripIt style disc on a 4" angle grinder. Save yourself hours, but wear a mask and contain the dust!
https://www.tradetools.com/tomcat-125mm-strip-it-disc-tsd125

Click to expand...

How long do they last Brian?
The guys tend to eat through a few of the normal discs so if these do a prop be a saving for sure

Not sure how many they used when they were doing it but guess 2 or 3 at most for a pair of 30 x 26 props. The yards I've been in the the last 7 years, Rivergate and GCCM, have always used them. They were using red ones rather than blue, which is the more abrasive I don't know. I thought it was standard practice to use them on metal parts.

I use a 3” heavy wire cup on a variable speed grinder. Never timed it but it does not take too long. Wear an n95 mask and tyvek suit minimum.

High Wire said:

I use a 3” heavy wire cup on a variable speed grinder. Never timed it but it does not take too long. Wear an n95 mask and tyvek suit minimum.

Click to expand...

I do the same but use a brass wire cup. Always an N-95

Rob

And eye protection!

some years back in a trade magazine, there was an add featuring the importance of eye protection, particularly when using a wire wheel.
The add sported a picture similar to this one.

Very effective advertising

And eye protection![/QUOTE]

+1 Sorry I left that out.

Rob

mike66 said:

And eye protection!

Click to expand...

Of course!

I usually cleaned my prop w acetone and Scotch Brite.

I used a wire cup brush on an angle grinder. Beware, you can remove a lot of bronze if not careful but it comes up shiny!

Nothing is faster and cleaner than a 3M Bristledisc on a 4" hand grinder.

OC Diver, You have come through for me once again. Your comment on prop sing sent me looking on the internet and I was able to confirm that the leading edge of the prob may be causing my prop sing or in my case a prop screech.

Prop singing - as it's referred to in the prop industry occurs when the leading edge of the prop is dulled to a blunt surface and not a 45 degree surface. Thanks for challenging me on this. I was able to find information on line and now the props are at the prop shop for a tune up.

The prop shop owner asked if the noise sounds like a person taking a wet figure around a crystal wine glass - and there it was! Thanks all.

JimL