Cleaning a prop

Benny17441 · Nov 18, 2015

Every 2 to 3 years we have the prop cleaned and painted with an antifoul paint. It makes it easier to maintain clean during the year and to clean when it is time to repaint.

capta · Nov 18, 2015

Power sanding a prop can unbalance it by taking away more metal from one area than another. I use muriatic acid to remove shell and coral from a badly fouled prop, but the stuff is very dangerous unless you know how to use it safely.

woodster · Nov 19, 2015

make sure you rinse that stuff off very well

capta · Nov 19, 2015

Rodd said:
Capta-
Your idea on the Muriatic reminds me that I use On/Off, all the time- which is, I believe, a muriatic acid concoction. Maybe I try the On/Off? Only thing is, will it harm the metal prop?
Thanks.

No harm to brass or bronze, organic substances very much so, but not brass or bronze.

seadaddler · Nov 19, 2015

Wire brush on portable drill works real well and the wire brush keeps
working for many other jobs and really cleans good with out any real work and use the wire brush on the shaft and many other jobs on my portable drill.

pateco · Nov 19, 2015

seadaddler said:
Wire brush on portable drill works real well and the wire brush keeps
working for many other jobs and really cleans good with out any real work and use the wire brush on the shaft and many other jobs on my portable drill.

Use one with brass wire. Steel wire will remove more bronze metal

woodster · Nov 19, 2015

pateco said:
Use one with brass wire. Steel wire will remove more bronze metal

better yet get a ss wire brush at the welding supply that works on a small angle grinder and have it all

rgranger · Nov 19, 2015

capta said:
No harm to brass or bronze, organic substances very much so, but not brass or bronze.

Ah.... hate to contradict but... muriatic acid is actually hydrochloric acid (stomach acid). And hydrochloric acid will dissolve zinc quite aggressively. Brass is an allow of copper and zinc. So I would not use muriatic acid to clean brass. And hydrochloric acid will react with tin. Bronze is an allow of copper and tin... so I would not use muriatic acid to clean bronze either. Given enough time and or if it is very concentrated the acid will leach out the zinc and/or tin in your prop. It might be safe to use if relatively dilute and if you don't leave your prop submerged for very long but there is a better and cheaper acid for the job.

Vinegar is a 5% solution of acetic acid. THAT acid is actually much more aggressive towards carbonates than HCl and seashells etc are made of mostly calcium carbonate. And acetic acid won't react with most metals. You can buy acetic acid as a 95%+ grade (called Glacial Acetic acid) and dilute that down by 2/3. That would give you a 33% acetic acid solution. Barnacle and other crud will foam off very fast. This is almost the same reaction as the child-hood "volcano" using baking soda and vinegar.

That would be a better way to chemically clean a metal prop.

A quick google search found this supplier of glacial acetic acid.... I'm a chemist so I can just pinch a little from work...

http://www.dudadiesel.com/choose_item.php?id=FGacet&gclid=CJPI5fyOnckCFUWWgQod7RwMaw

njlarry · Nov 20, 2015

Thanks for the tip. Fascinating that the stuff freezes at 62 degrees!
Ps, I think that you should enter your avitar in the next photo contest.

, it has my vote.

rgranger · Nov 20, 2015

njlarry said:
Fascinating that the stuff freezes at 62 degrees!

Also important!!!! Vinegar will chemically react and neutralize the monomers in epoxy resin (before it sets). So if you are doing any epoxy work... keep a bottle of cheap vinegar and a wad of paper towels nearby. If you get it on your skin or tools, just wipe it off with a vinegar soaked towel and the resin comes right off (if it hasn't set yet).

Graycruiser · Nov 23, 2015

Rodd said:
This year I will not be removing my prop. There is a bunch of white scale on the prop, and I was wondering the best way to clean it off. Sometimes I sand the blades with a random orbital sander and 80 grit paper after chiseling off some of the larger crud, but this method goes through a lot of paper. Anyone have a better suggestion?

Thanks.

We have about 30 boats in our club at our marina on the upper Chesapeake Bay where the waters are mostly fresh to slightly brackish depending on rainfall, and location. A few years ago we conducted a test of prop protection. About 12 boats participated. They were to use whatever they preferred and the results were monitored prior to launch and after haul-out. A variety of methods were used from bottom paint, expensive prop paint, high zinc primer, etc. The winner hands down was the 90% zinc primer. You can pay $20+ in a marine store or about $8 in a home store. Same stuff, more or less.

Application consists of removing all foreign material from prop and hub. Polish surface to remove any corrosion. A light sanding may help to provide some "tooth" to the surface. Immediately before spraying, clean the surface with mineral spirits or similar. That's it. Maybe 30 min.

Graycruiser · Nov 23, 2015

rgranger said:
Vinegar is a 5% solution of acetic acid. THAT acid is actually much more aggressive towards carbonates than HCl and seashells etc are made of mostly calcium carbonate. And acetic acid won't react with most metals. You can buy acetic acid as a 95%+ grade (called Glacial Acetic acid) and dilute that down by 2/3. That would give you a 33% acetic acid solution. Barnacle and other crud will foam off very fast. This is almost the same reaction as the child-hood "volcano" using baking soda and vinegar.

That would be a better way to chemically clean a metal prop.

I second the vinegar recommendation. A few years ago we were out for 3 weeks towing a dinghy. When we hauled the dinghy the bottom was covered with very small barnacle buds. I sprayed it with vinegar, covered with newspaper and sprayed the newspaper to keep the bottom wet. After a couple of hours, the baby barnacles scraped off easily. Also use vinegar on the prop to remove the barnacles (calcium carbonate). Works well.

rgranger · Nov 23, 2015

Graycruiser said:
We have about 30 boats in our club at our marina on the upper Chesapeake Bay where the waters are mostly fresh to slightly brackish depending on rainfall, and location. A few years ago we conducted a test of prop protection. About 12 boats participated. They were to use whatever they preferred and the results were monitored prior to launch and after haul-out. A variety of methods were used from bottom paint, expensive prop paint, high zinc primer, etc. The winner hands down was the 90% zinc primer. You can pay $20+ in a marine store or about $8 in a home store. Same stuff, more or less.

Application consists of removing all foreign material from prop and hub. Polish surface to remove any corrosion. A light sanding may help to provide some "tooth" to the surface. Immediately before spraying, clean the surface with mineral spirits or similar. That's it. Maybe 30 min.

Wow! That is really interesting. So expensive bottom paint did not fair as well... So does that imply that cold galvanized (rustoleum) compound would make a decent bottom paint ? Anybody up for another experiment...

Gunni · Jan 10, 2016

Never paint bronze with a copper-based anti-fouling paint. Zinc is not a very effective anti-fouling, as recent formulations have demonstrated, but for a prop zinc paint is somewhat effective and protects your bronze prop.

Charles Erwin · Jan 10, 2016

Gunni said:
Never paint bronze with a copper-based anti-fouling paint.

Can you tell us why exactly?

Gunni said:
Zinc is not a very effective anti-fouling, as recent formulations have demonstrated, but for a prop zinc paint is somewhat effective and protects your bronze prop.

Can you tell us which recent zinc formulations?

Charles