Painting and Cleaning a Prop

[Earl S]

Last year I installed a new Maxi prop along with a new Yanmar engine. When the boat was pulled for winter layup the bottom was power washed and looks to be in good shape. The prop had some barnacles and they were scrapped off but left some spots on the bronze. My question is 'How do I clean the barnacle stains off the prop and will a zinc chromate primer paint followed by an ablative anti-fouling paint protect the prop from barnacles?’

 

[Don S/V ILLusion]

Timely question Earl - there are a few methods which appear to be popular. See recent discussion which should answer your questions:

http://forums.hunter.sailboatowners.com/showthread.php?t=106058

 

[CaptainJB]

Nothing Works

I live in Northern Florida and the boat is in the water 12 months per year

During the Summer I dive under and clean, but even in Florida the water is to cold in the winter so I resorted to that two part green mixture. I think it is a Petit product but am not certain. I just went looking for it to type in the name and realized I recently loaned it to a friend who it appears hasn't returned it. That's my next e-mail......

But getting back to the issue, this stuff isn't cheap, $40 - $50 for a small can. Based on the boats performance I needed to hire a diver to clean the prop. His observation, barnicles love the stuff.

I am therefore also looking for a better solution

 

[Warren Milberg]

After scraping my bronze prop (and shaft), I clean and polish it with emory paper. I usually start with about 400 grit paper and finish up with 800 or 1000. Works very nicely. As to what to protect the prop with, I think that "Prop Speed" is about the best, but much too expensive for me. Don's link to the thread on this subject covers a lot of other products. I currently use Petit Zinc Barnacle spray and it "satisfices."

 

[Maine Sail]

Copper Based Paints = No

Last year I installed a new Maxi prop along with a new Yanmar engine. When the boat was pulled for winter layup the bottom was power washed and looks to be in good shape. The prop had some barnacles and they were scrapped off but left some spots on the bronze. My question is 'How do I clean the barnacle stains off the prop and will a zinc chromate primer paint followed by an ablative anti-fouling paint protect the prop from barnacles?’

Earl,

It is not advisable to paint a prop with a copper based paint as the dissimilar metals can set up a nasty galvanic situation. Max Prop will advise against painting it if you call them and ask. MaxProps are made of Nibral and thus contain aluminum which is lower on the galvanic scale than copper is. This means the aluminum in your prop could become the sacrificial metal to the copper in the paint..

If you use anything to paint your prop make sure it is safe for underwater metals specifically Nibral (Nickel/Bronze/Aluminum)..

This is the result of a manganese bronze prop being painted with a copper based bottom paint. The pink/coppery colored areas are dezincification of the prop. My prop shop would not even work on it as, in this condition, it's a liability...

 

[Earl S]

Thank you all for your input and a special thank you to Main Sail. I'll heed your advice.

Earl

 

[Ariel]

Earl,

We keep our boat at The Sailing Emporium in Rock Hall, in the warm inner harbor. For the past two seasons we have coated the prop and the strut with Pettit #1792 Zinc Coat Barnacle Spray with very good results. Each fall we clean the few barnicles that grow over the summer with a mild brush in an electric drill. Then each spring we spray a coat of the zinc paint prior to launch. The Pettit zinc spray was recommended for the Max-prop by PYI.

We live aboard during the summer and cruise extensively, so the engine is used a lot. The zinc does not "spin" off the prop as paint does and the effectiveness of the paint lasts all season.

We will keep an eye out for you this season. I believe you must be on the Swan Creek side of town.

Dave
s/v Ariel