Polishing a new propeller - worthwhile?

[MM5AHO]

After 40 years service, I decided it was time to replace my propeller. The original was bronze, as is the replacement. Nearly identical, but the new one has a slightly larger area on each blade.

But my question is: should I polish it?

It comes part polished. Sanded with what I'd guess to be about 120-180 grit paper/disc. I know that I could do this with successively finer grit down to about 3000, then some rouge or metal polish and I'd get a mirror finish.
It would look nice, but only out of the water.
Does a polished prop work better?
Does a polished prop allow less marine growth to get a grip?
Any other considerations?

 

[jwilson]

A polished prop certainly works better, till it gets fouled. High speed boats seem to have more success just polishing props, when I tried it on a low powered sailing yacht it was a spectacular failure after just a few months.

Personally I sand to clean and key, a coat of zinc primer, then two of Seajet 33 or Micron, depending on offer price each year. After 8-9 months in a pretty high fouling area not much AF left on, but no barnacles, and still very little difference in top speed under power from the day it launched. Typically 7.9 to 8.0 knots flat out at launch in March, 7.7 to 7.8 on way to haulout in October or November.

 

[NormanS]

It'll certainly look better on the coffee table as a wintertime conversation piece. At normal yacht cruising speed, I wouldn't think it would make one iota of difference. But hey, if you've got the time and inclination, why not?

 

[Hoolie]

Because it makes applying anti-foul like Velox virtually useless as it won't stick!

 

[Marine Reflections]

After 40 years service, I decided it was time to replace my propeller. The original was bronze, as is the replacement. Nearly identical, but the new one has a slightly larger area on each blade.

But my question is: should I polish it?

It comes part polished. Sanded with what I'd guess to be about 120-180 grit paper/disc. I know that I could do this with successively finer grit down to about 3000, then some rouge or metal polish and I'd get a mirror finish.
It would look nice, but only out of the water.
Does a polished prop work better?
Does a polished prop allow less marine growth to get a grip?
Any other considerations?

Yes, polish it.
As per your thoughts of a mirror finish.

Think in terms of prepping a surface so something will stick to it, now think in terms of prepping a surface so nothing will stick to it.

Props are interesting little gems of surface interaction, much is at work and I'm sure in the future we'll see all sort of new developments in micro surface advancements.

 

[prv]

Yes, polish it.
As per your thoughts of a mirror finish.

I tried that with mine when first installed - polished it finer and finer down to Brasso on cotton wadding, so I could have shaved in it like a mirror.

Didn’t work worth a damn, I dived on it a few weeks later and it had a healthy crop of small barnacles.

Switched to antifoul ever since.

Pete

 

[vas]

I'm in the rough and antifoul camp!

after 4 different approaches to keeping props clean, a grp repairer man gave me a hint last spring as Velox would flake out within the first half hour of operation...

OK, basics mean rough it down to grit 60 or 80.
get the velox primer and velox antifoul (bleeding expensive for their volume btw!) into spray cans. A decent hardware store can do that for you!
Shake well and apply. Make sure you just get a tiny cloud on each go. Wait a 5-10mins and repeat. Make sure you finish off with the primer in ONE GO, don't leave for next day probably wont work out of the can unless you have a new nozzle.
Apply the a/f can in a same way.
BTW, I did approx 4 thin coats of each primer and a/f. Ah, and I did test a galvanised steel primer already in a spray can and 1/3 of the velox primer and it did stick so will use that for any tiny repairs I'll need in the next year.

Was impressed that after 3months and 26C+ marina water temp in a high foul area props were clean and most important a/f was still there!

The explanation he gave is that applying it with a brush creates too thick a layer and cannot adhere to prop properly as it's spinning as tiny ripples in application create massive forces against the water flaking it all off. Wasn't fully persuaded back then, but now I definitely believe him!

cheers

V.

 

[Skylark]

Another advantage of Antifouling the prop is that it reduces the cathode surface area and hence gives the anode less work to do. Over a typical 6 month season, I find the difference to be quite significant.

 

[CAPTAIN FANTASTIC]

I always anti foul my propeller, it keeps barnacles off and as others said, it helps with the anodes. A polished propeller looks wonderful when out of the water.

 

[geem]

We polish ours here in the Caribbean. Its not a problem to keep it clean with a bit of snorkeling and a pan scrub. Would be a different story in cold water.

 

[dunedin]

I tried that with mine when first installed - polished it finer and finer down to Brasso on cotton wadding, so I could have shaved in it like a mirror.

Didn’t work worth a damn, I dived on it a few weeks later and it had a healthy crop of small barnacles.

Switched to antifoul ever since.

Pete

My experience has been the opposite. Fouled very badly when painted with the recommended International stuff.

Been fine before and after using the smooth and polish approach

 

[Hydrozoan]

I polish my two-blade folder ritualistically and it seem to work well, with just a few barnacles.

 

[savageseadog]

Polishing. Complete waste of time but it is worth scouring it with a plastic kitchen scouring pad if it's a bit overgrown. I've never needed to though.

 

[NormanS]

I clean my prop with a wire cup brush in an electric drill. Just before launch, I slather it with underwater grease. For all I know, it might be all off in the first five minutes, but I've never had serious fouling.

I'm interested in the notion that antifouling, or presumably any paint that will stay on the prop, will extend the life of the anode. I find after six months that my nosecone anode is pretty much eaten away, so I might try antifouling this year and see how it goes.

 

[MM5AHO]

Thanks, a mixed response of yes, no and maybe!

Well, I polished it today. Was about what it might be with about 80-100 grit, now mirror finish, so will be interesting to see what happens.
I've read about people putting egg white on their prop as anti-foul, but I can't see why that would work?
I once antifouled the old prop, but there was no trace of that after a summer. The old prop was just cleaned each year.
I do 't have an anode anywhere on my boat, so the lower surface area idea doesn't really apply.

 

[Neeves]

Vyv electro copper plated his prop and the electro plater polished it for him. He was reticent about quoting his experience here as he wanted to earn a few pounds by publishing the results (seems a good way of paying for the work and disseminating the result). I'm not a subscriber, so don't know if he published, but he might be more forthcoming to a PM.

But the idea sound sensible - polishing and copper.

Jonathan

 

[doug748]

Thanks, a mixed response of yes, no and maybe!

W

I have polished mine for, maybe, the last 10 years. Once you get a good shine on it is easy to restore it each year. The results are pretty good for a couple of months and then it really needs a brush up, which is very easy provided you can get down to the prop.

If left to the end of a six month season I found it roughly the same as an anti fouled prop, except a rub with very fine emery cloth brings back the sparkle.
I did read the other day that someone found it made his prop "sing", at least until it gathered a bit of growth.

I tried lanolin, as well, one year which seemed to make no difference.

 

[vyv_cox]

Vyv electro copper plated his prop and the electro plater polished it for him. He was reticent about quoting his experience here as he wanted to earn a few pounds by publishing the results (seems a good way of paying for the work and disseminating the result). I'm not a subscriber, so don't know if he published, but he might be more forthcoming to a PM.

But the idea sound sensible - polishing and copper.

Jonathan

That's not the reason I have said nothing. Health problems and other time-consuming activities have prevented me from drying the boat to have a look. It has now been immersed for nearly two years. Hopefully I will see it in March. But after six months on a drying mud berth it looked very promising.

 

[Malish]

I'm interested in the notion that antifouling, or presumably any paint that will stay on the prop, will extend the life of the anode. I find after six months that my nosecone anode is pretty much eaten away, so I might try antifouling this year and see how it goes.

I'll support it. I fitted a Featherstream and primed + antifouled using a combination which did not stick well in year 1 with plenty of exposed prop metal + barnacles by the end of the year: net result was the requirement for a new anode at the end of year 1. At the start of year 2 I used Hammerite Special Metal primer + velox antifoul. Not only is the top coat better at repelling barnacles but the primer has stuck like sh*t to the prop and I have not needed to change the anode in 3 years.. a result in my book.

 

[vyv_cox]

I'll support it. I fitted a Featherstream and primed + antifouled using a combination which did not stick well in year 1 with plenty of exposed prop metal + barnacles by the end of the year: net result was the requirement for a new anode at the end of year 1. At the start of year 2 I used Hammerite Special Metal primer + velox antifoul. Not only is the top coat better at repelling barnacles but the primer has stuck like sh*t to the prop and I have not needed to change the anode in 3 years.. a result in my book.

Very similar experience to mine, Bruntons Autprop. Prop anode and a shaft anode: their life at least doubled.