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Asleep at the wheel
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When I visited my boat yesterday, the prop still basically looked like this:


Someone had suggested that cleaning the prop might help with performance. I'll admit that it is isn't mirror-smooth, but it's not like I have 3" wide/long barnicles growing on it or anything. Is it really worth trying to clean the prop more than it already is? If so, what's an appropriate approach?
 

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Old as Dirt!
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When I visited my boat yesterday, the prop still basically looked like this:


Someone had suggested that cleaning the prop might help with performance. I'll admit that it is isn't mirror-smooth, but it's not like I have 3" wide/long barnicles growing on it or anything. Is it really worth trying to clean the prop more than it already is? If so, what's an appropriate approach?
Jim--

Any growth on the prop effects performance and only a few barnacles can quickly grow into a colony. Use a scraper to remove the barnacles and then a cloth soaked in "Lyme Away" to get rid of the craters left behind. Than take some fine bronze wool and polish the blade somewhat. You might also try using a product known as "Prop Glop" to slow down the development of growth in the future (although it will need periodic reapplications).

FWIW
 
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Have found once you get the gunk off using a polishing wheel with rouge to get a high polished finish is a help in keeping growth off.
 

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BTW, you might want to put a zinc on that shaft while it's out of the water.
Wouldn't expect to see a zinc right there, Mark.. probably/hopefully something on the other side of the strut (assuming it is a strut)..
 

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Is there a difference in the rate of growth depending on the prop material? Like aluminum vs. bronze?
 

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You might want to remove that prop and get it into a prop shop. It needs to be balanced and they need to check the blades. There appears to be some old corrosion as well. They'll return it nicely polished. If you want to just clean it in place, muriatic acid is the right tool for that job. It's extremely DANGEROUS to work with, blah, blah, blah.... You'll probably want to polish the shaft with emery cloth before you replace the zinc, too.
As for degrees of fouling, even a few barnacles can mess with the balance of a prop and that can seriously shorten the life of your cutlass bearing.
During our haul out last month in Trinidad, Alan sprayed a grey paint on the running gear and it's supposed to inhibit growth; if it even helps a little, I'll be surprised. I've even tried chroming props to reduce fouling and had absolutely no joy. I figured nothing could grow on slippery, high quality chrome; wrong.
 
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Asleep at the wheel
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Discussion Starter #10
Any idea what a prop shop would charge to clean and balance it? Any suggestions for one in/near NJ or Philly? I have toyed with getting a 3-bladed prop (the Campbell Sailor), so just trying to see if it's worth putting the money into this one or if I would be better off just getting a new one.
 

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Jimgo, do you haul every year? Do you clean your boat's bottom and prop/strut during the year? You have a lot of growth there (strut) and the growth on the prop does impact performance. Other than growth, your blade tips look in pretty good condition. The prop nut however... You wouldn't want to see my prop & strut as I use a polishing wheel and compound for my last step. Before you think about a three blade, you will need to do some basic engineering work like calaculating pitch and diameter to match the HP of your engine and that extra blade is like dragging a bucket when you are sailing.
 

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Discussion Starter #12
George,
The boat is "new" to us. We bought her in March, and were focused on other aspects of the power system for a few months (my blog has details, if you're interested). Now that things have calmed down and we're out for the season, I'm starting to put together the list of projects that I can take home with me and work on over the winter. I have some experience polishing metals, but I just wasn't sure how much ROI I'd get for the work of polishing the prop. I'm told that our marina doesn't get a lot of barnacles (unlike the Chesapeake, where the boat spent the past several years).

Regarding the CS prop, they've actually taken care of the calculations for me. Several other Allmand owners have bought, and love, the props, so "all" I had to do was call them and they pulled the info. As I understand it, the CS props tend to give Allmands less prop walk and, since they push more water, they give better steering control at lower RPM's than their 2-bladed cousins.
 

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Polishing the prop improves its performance. Well worth the time.

If you are sure it is a bronze prop, then there is no need for a zinc anode. Without a zinc, barnacles will not grow on the prop.

Many props are in bronze, but not all. Some are made in brass. Brass do need a zinc, outherwise the brass will de-zincify (?).

When you are considering swapping to a 3-balde, would that be a fixed one, or a folding? It is certanly true with the advantages of a 3-blade, but but ... if it is a fixed one, it will cause much more drag.
Folding 3-blad is good, but expensive.
Sometimes said 3-blade is mainly for > 30 hp. Rule of thumb, doesn't mean it cannot be used at lower power.

Note also, which may surprice, a 3-blade is not as power efficient as a 2-blade.

Summary: Try polishing. As good as possible.

/J
 

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The prop shop I used a few years ago in NY checked the balance on my 2 blade prop for free (they were doing other paid work for me). Should not cost a lot for them to check it or "spin it" as they call it.

Good luck getting your prop off the shaft while it is that dirty. Hope you can find a prop puller rig and a whole bunch of patience.
 

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The prop shop I used a few years ago in NY checked the balance on my 2 blade prop for free (they were doing other paid work for me). Should not cost a lot for them to check it or "spin it" as they call it.

Good luck getting your prop off the shaft while it is that dirty. Hope you can find a prop puller rig and a whole bunch of patience.
Most props will pop right off with a puller under pressure and a bit of heat. The bronze expands much more quickly than the S/S. No banging or sprays.
 

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As many have said, a polished prop will take on new growth much slower. I've never had it professionally polished alone, but have had them come back polished after a repair. Can't be too expensive, but I'm sure you could do it yourself. Take it off and bring it home. Easy.

Had a buddy spray his with Petit Zinc Coat Barnacle Barrier paint last spring. I just saw his prop on the hard last week. Almost no growth and the paint was only partially worn. I was surprised.

Needless to say, if you do this, it must start totally clean.
 

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The expensive solution to the growth problem is Propspeed. At our dock, past couple of hot summers, I've seen 80 degree water. Without the coating the prop was completely barnacle covered (took me 30 mins with a scraper and scuba). With Propspeed we make it through a season. YMMV, we are in a small, warm, Cape Cod bay.
 
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