Zinc disappeared fast...Ranger 21 EC

[harley]

I have a Ranger 21 EC I purchased last year. It had all new zincs when I bought it. I had it in salt water on a buoy for five months...NO shore power connection and no other boats nearby.
Symptoms:
1. Prop zinc completely gone. Bolt still there, so it did not come unscrewed.
2. Rudder and strut zincs have very little deterioration. Strut a little and Rudder almost none.
3. As said before...not on dock...no shore power connection
4. I do have a new solar panel
5. When I bought the boat...it was in fresh water lake but seller had no idea what kind of anodes he had on the boat(for fresh or salt water...since they are different).

Questions:
1. Can boat unplugged waste a zinc that fast? I have had boats for 37 years in salt water and never had a zinc go that fast.
2. If the boat had fresh water zinc in salt water on shaft...would it go away quicker?
3. Is there a test for stray current I can do...and does it need to be in the water to test?

Boat is hauled now for paint and replacing all anodes with proper salt water zincs.

Hbob

 

[harley]

Does anyone know about the bonding system on the Ranger 21 EC....2010 model era?

 

[Kevin Lamont]

I have a Ranger 21 EC I purchased last year. It had all new zincs when I bought it. I had it in salt water on a buoy for five months...NO shore power connection and no other boats nearby.
Symptoms:
1. Prop zinc completely gone. Bolt still there, so it did not come unscrewed.
2. Rudder and strut zincs have very little deterioration. Strut a little and Rudder almost none.
3. As said before...not on dock...no shore power connection
4. I do have a new solar panel
5. When I bought the boat...it was in fresh water lake but seller had no idea what kind of anodes he had on the boat(for fresh or salt water...since they are different).

Questions:
1. Can boat unplugged waste a zinc that fast? I have had boats for 37 years in salt water and never had a zinc go that fast.
2. If the boat had fresh water zinc in salt water on shaft...would it go away quicker?
3. Is there a test for stray current I can do...and does it need to be in the water to test?

Boat is hauled now for paint and replacing all anodes with proper salt water zincs.

Hbob

Hey Bob,

I believe we had a procedure on how to test for stray current on the bonding system but having a hard time finding it. I know there is a way to test this and wonder if the solar panel is giving stray current? It does seem odd that the prop zinc wore off so quickly, were you using the boat during those months? I know that they will flake off as they are spinning at engine RPM's.

Thanks,

 

[Red Raven]

Harley,

If your prop zinc on the R21EC is similar to the one on our R27 I may have an explanation. I have lost the prop zinc before with the bolt still in place. I think what happened is that as the zinc is consumed it becomes smaller and is no longer held tight to the prop nut (even with the bolt fixed by thread locker). When the shaft is spinning and the zinc is loose it bangs around quite a bit. When shifting from forward to reverse and back it bangs even more. I suspect my zinc (and yours) just broke apart and fell off.

Here are a few other supporting tidbits:
On our way home from a trip (not the year I lost the zinc with the bolt still there) after only 3 months in the salt I could hear a distinct unusual rattle and vibration. At the dock that evening I went for a little dive to check the prop and shaft. Not only did I find some eel grass around the shaft but the zinc was really loose and make the telltale sound heard while underway when I moved it back and forth. A quick tighten of the bolt and the zinc was good for the rest of the summer (changed at 6 months). This confirmed for me where the zinc had gone previously.

As Kevin mentions the prop zinc also sees mechanical wear from the spinning shaft in the water.

The prop zinc on our boat does erode faster than the other zincs. Perhaps it is the mechanical wear or perhaps has to do with the greater galvanic potential from the connection to the stainless steel shaft. I’m not sure, but it does erode faster. I get 6 months max, even with additional transom and rudder zincs.

If your bonding is good I doubt the solar (or any other electrical issue) had anything to do with it. The other zincs would also have been degraded.

If you do a search there and several discussions here on Tugnuts on how to make a more secure connection. I have tried most all of them. My current favorite is to add three stainless washers to the bolt on the inside of the zinc prior to screwing it on the prop nut (there is a gap without the washers). This locks it tightly to the nut even as the zinc erodes. I also use plenty of thread locker. This has worked well for the last couple of seasons. I get 6 months before changing the zinc.

Curt

 

[harley]

Curt,
Thank you...I am new to the boat so I did not check nut on zinc but will on the new one. I did run a lot of hours the past six months.
Harley

 

[Newf]

Hi Harley
Can't help with the bonding or stray current questions because I have very little understanding of it. If the anode came loose and failed because it rattled around it may not have been installed properly. When I did the cutlass bearing changeout a few months back I had an issue with installing the new zinc. I could not get it to tighten against the heavy washed that sits against the prop.

It may not be clear in these photos but the prop nut does not tighten the heavy washer against the prop. The nut seats directly against the prop and this washer is still "floating". In the first photo it looks like the nut is tight against the washer but that's because it's locked there by crap and crud. Once I cleaned it up for reinstallation the next photo shows that it's not tight against the prop. The last photo shows that the nut protrudes through the washer by 1/16" or more. Not sure why it's designed this way but that's how it is on mine. I was actually going to grind it flush but decided to leave as is.

When you install the zinc it should tighten down against this washer and the prop hub. When I first installed my zinc, this washer was still loose as shown. I pulled it off again and found that the cotter pin through the prop nut was not positioned and crimped down properly and prevented the zinc from going on far enough to squeeze against the washer. After I crimped it down properly I could tighten the zinc against the washer which then seated against the prop hub. I pull my boat out after every use so can inspect after every launch and have had no issue nor did I had any in the previous 7 years with the zinc coming off.

This may or may not have anything to do with why you lost your zinc but thought I share that as another check to do when you install your next one. If this is not very clear shoot me a PM or an email and I'll try to explain it a bit better.

 

[lproulx]

I have a solution that won't work for everyone, but if you can do it it is good. I got tired of that Mickey Mouse prop anode situation. I happen to own a metal lathe. I buy a collar type anode made to fit around the prop shaft. They are a little too thick to fit between the prop hub and the boat, so I just stick it in the lathe and turn the faces down enough so it will fit with about 1/8 in to spare to let water into the cutlass bearing in the boat. You could probably reduce the collar thickness with a hack saw also.

Larry

 

[ohioan55]

I've not seen mention of what type of metal was used for the anode. Zinc is good for salt water, but seeing how you mentioned the boat came from fresh water, the anodes may be aluminum or magnesium. Zincs are not a good choice for fresh, but here's what I'm getting at. If they are aluminum, they may not last long in salt water with a little stray current from to solar panels.

 

[MontereyTug]

I had someone accidently use Magnesium anodes on my salt water boat and they were severely degraded in under 90 days. If the rattle around and break off theory isn't the answer my guess is you had Magnesium anodes.

 

[harley]

I had someone accidently use Magnesium anodes on my salt water boat and they were severely degraded in under 90 days. If the rattle around and break off theory isn't the answer my guess is you had Magnesium anodes.

Since it is gone and I cannot test for type of metal....I should assume that is the issue and will keep a close I on it after it launches. I will also test the bonding connections.
Thanks for all the help.

 

[harley]

I had someone accidently use Magnesium anodes on my salt water boat and they were severely degraded in under 90 days. If the rattle around and break off theory isn't the answer my guess is you had Magnesium anodes.

That is the best bet for what happened. Since the engine-shaft-prop anode is the most likely path of electricity, the shaft anode would deteriorate the fastest if the wrong metal type. I will keep an eye on it.
Thanks for the help.
Harley