Friday, November 7, 2014

Shiny Props or Battleship Gray

Another task that is easier (no I didn't say easy) to do out of the water than it is in the water is cleaning the props.  But I'm waiting on parts and can't find an excuse to procrastinate any longer, so it is time to tackle that task.  The propellers didn't look as bad as the one on the other leopard I surveyed, but they could still stand a cleaning.

I figured I needed a flexible scraper, a wire brush, some sandpaper, and maybe a Scotch-brite pad or two.  I started with the scraper.  I chipped the remnants of the barnacles and other stuff off...slowly.  This stuff is like cement.  It took quite a while with the scraper before I got down to the bronze.  For the tight spots where I just couldn't work the scraper, I ended up using the wire brush and sandpaper.  After I got the prop clean, I went over it with the sandpaper to get the last bits off the prop.  I think it took about 3 hours per prop to get them reasonably shiny and clean. The truth is, I never used the Scotch-brite, I quickly realized that a Scotch-brite didn't have a chance.

1/3 of a clean prop

Originally, I wasn't intending to coat the propellers with anything, but after all the work, I was re-evaluating that decision.  I couldn't use bottom paint since the ablative paint wouldn't stay on the props for long.  Fortunately, there are a few prop coatings available. In doing my research on propeller coatings, I found out that Rust-oleum Cold Galvanizing Compound is virtually the same stuff as one of the propeller coating products...and at $7, it was an economical alternative to the $22 can of official propeller coating.  So, I got a can of it to give a try.

Shiny prop with sad looking zinc

Painting the propeller was pretty easy.  Simply mask off the area from overspray and apply a couple light coats of paint and let it dry.  The props aren't shiny anymore, but hopefully they'll resist some growth or, at least, may be a bit easier to clean.  Guess I'll know next time we haul the boat how effective it is.

One last task and the props will be ready to go.  That broken piece of metal at the end of the props in the above pictures were the remains of the sacrificial zincs and they obviously needed to be replaced.  Simply remove the alan head bolt holding it on and replace with a new zinc.  Yeah, right.  One zinc came off just fine, the other bolt would not budge.  I broke a hex wrench trying to get it off.  Fortunately, the prior owner had a supply of zincs AND prop nuts, so I ended up having to remove and replace the prop nut as well as the zinc.  I replaced the prop nut, bent up the tab on the keyed washer to lock the nut in place, then installed the zinc with a little Lock-tite on the hex bolt.

Painted prop with unpainted nut and new zinc

So, other than the touch up bottom paint where the stands are covering the bottom, the underwater surfaces should now be ready to go back in the water.


  1. I wanna know how that paint works so keep us posted. We used the $22 stuff and it's worked fairly well but we still have to scrape the prop twice as often as the bottom.

    S/V Kintala

  2. You might want to check out

    Your paint will not really protect against marine growth... Will be interested in a follow-up article in a year when it's time to do this again. Of course, using your boat every day or two (like you will be while cruising) will tend to keep them cleaner than many of us who are only sailing on the weekends.

    1. Hi Doug. I'm not really expecting to do much to inhibit marine seem to indicate most of the prop treatment options don't do so well. I just hope it makes the prop a bit easier to clean. Only time will tell. Will check out your link when I get back to better Internet coverage (in the process of heading south now).