Prop zinc eroding faster than any other zinc

[baz]

I have my underwater zincs checked every 3 months. I'm finding that my prop zinc is by far the greediest in that it is always around 50% to 60% eaten away. None of the other come close to this. So it seems the prop zinc is taking all the work for protecting the boats metals.

What do others experience I wonder for their R25s ?

 

[knotflying]

I have an R-27 and the worst I saw was the engine zincs. I got the boat in April and when I changed them in September as part of my winterization process one of them was completely gone and the other half gone. The other zincs were not too bad. However, I keep my boat on the trailer most of the time, with 2 week periods, at most, in the water probably 4 times throughout the summer. I was surprised at how quickly they deteriorated.

 

[HRowland]

I have a R27 and my problem is the trim tab zincs. Our R27 was delivered at the end of May and it went through 2 sets of trim tab zincs. When pulled for winter layup at the end of October the prop zinc was nearly gone. Shortly after the first set of trim tab zincs were consumed I started using a hanging zinc that was clipped to the boats ground. It is noticably thinner.

I had it connected to the marina power all summer which is probably accelerating the zinc consumption. I will be installing a galvanic isolator over the winter.

The thruster anodes are less than half gone but I will still be replacing them in the spring. Side Power says the external thruster metal is electrically isolated which would explain why they did not erode as much.

From BoatZincs.com: "Imtra Side-Power thrusters are engineered to have their underwater metals electrically isolated from the rest of the boat. This means that there is no electrical path available for the thruster (or its anodes) to interact with any other underwater metals (or anodes) either on or adjacent to your boat. You can, and should, continue to use zinc anodes elsewhere on your boat while upgrading your Imtra Side-Power thruster to these new, technically superior aluminum anodes."

I have not checked the engine or generator zincs yet, this will be another thing to check over the winter.

Howard

 

[Lobo]

You should add a sacrificial zinc anode to your electrical system. See West Marine “Grouper Anode – Model 485144 $42.99 US” – page 357 in the 2011 catalogue.

The anode comes with a “jumper cable clamp” that I discarded and replaced with permanent hard wiring into the ground in the engine compartment.

If I’m plugged in, the zinc is overboard.

Ron (Sidetrack Charters, R25) gave me a commercial zinc of several pounds so I now have that hanging overboard. It helps. And use a stainless steel wire brush to clean the scaling off the zinc.

This should slow the deterioration of your prop zinc somewhat.

Dave

 

[Levitation]

For an experiment:
I am suspicious that sometimes the electrical path across the shaft coupler is not good...
When the boat is to be left in the water for some time use a (battery) jumper cable to clamp to the prop shaft down in the bilge and the other end to the ground cable on the engine... See if that reduces the rate of erosion of your prop zinc...

 

[sparky]

After going through prop zincs every 6 weeks, even trying the zinc guppy from West Marine (the one people describe as clamped to the battery and hung overboard) we ended up having two electrical surveys of the boat, neither found any real fault, but one recommended that we add a larger stern zinc, which we had installed (since it is bolted through the hull under the waterline at the stern, obviously the boat was hauled) AND the DairyLand Galvanic Isolator. Things got much better.......especially when we found an out-of-the-water. But even with all that work, our West Marine GalvanAlert (a device that connects between the boat's shore power inlet and the shore power cord) the gizmo indicates that we still have a high corrosion potential. I give up.

 

[doke01]

Sometimes the erosion of zincs is not caused by your boat but by the boats and/or docks around you. Just because they are deteriorating does not mean your boat is the cause. I tend to suspect where my boat is located over the boat itself as being the cause when I see excessive depletion of the zincs and, for the most part, changing the location of my boat had reduced zinc consumption in the past.

 

[bbrh842]

There is an article about this subject in the current issue of Boat U.S.
Look in the "Ask the experts" section.

 

[Levitation]

Sparky, if the marina has faulty wiring (or boats) putting current flow in the water and you are moored between the source of electron flow and the 'ground', nothing you do on the boat is going to make your galvanic indicator happy...

My suggestion is next time you take the boat somewhere else, is to plug in at that dock and see what your indicator shows...