Oucheeee - replaced underwater zincs at 6 months on R-27/OB

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Subject: Oucheeee - replaced underwater zincs at 6 months on R-27/OB

I had to replace all the underwater zincs/anodes on my new (6-1/2 months old) R-27 OB. It had been kept in salt water at my Edmonds Marina in PNW.

This was quite a surprise for me....

Photos here http://www.tugnuts.com/gallery2.php?g2_itemId=53196
 
I’m going to be pulling my Cutwater 28 here in a month or so. Been in the water since last July, when it had brand new zincs. Kind of nervous to see what things look like. Not the first person I’ve seen or heard something like this from with the RT/CW. My previous boat was a Sea Ray with a mercathode system, so I didn’t even have to do it annually thanks to that.

A galvanic isolator is already on my spring to-do list!


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Stray current can cause rapid zinc loss. Having a galvanic isolator protects against stray current from nearby dissimilar metals, for example in-water iron supports on marina docks. It's cheap protection!
 
gsc3":e12hjz24 said:
Stray current can cause rapid zinc loss. Having a galvanic isolator protects against stray current from nearby dissimilar metals, for example in-water iron supports on marina docks. It's cheap protection!
Click to expand...

That’s how I’m looking at it. I was sort of shocked that boats like these aren’t built with isolators already (I didn’t realize that at first - just assumed they were).

I don’t have a truck or trailer, so the way I look at it, the cost of an isolator will be a lot less than the cost of hauling it out for frequent zinc changes!



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I installed a ProMarina GI on my R-25 (Classic) and it made little difference (if any) to the rate of my underwater zincs eroding. I have diver service and they concluded I had basically wasted my money. My zincs are always replaced if they are at 50% or less during each inspection; the idea being that zincs reaching 0% are worthless protection.

My advice... If you do install a GI keep good records to satisfy yourself it was worth it.
 
Interesting. I’ve talked to a couple folks that have installed them and they said they got significantly longer life from their zincs after that.

How much is the diver service costing you? I’m not sure that’s even an option around me (Potomac River). Not sure how much you could even see underwater! [emoji3]


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eric9603":1vq32d0h said:
Interesting. I’ve talked to a couple folks that have installed them and they said they got significantly longer life from their zincs after that.

How much is the diver service costing you? I’m not sure that’s even an option around me (Potomac River). Not sure how much you could even see underwater! [emoji3]


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Click to expand...

Cost for diver service depends on what they do & replace.
My photo Album I referenced shows that things can be easily seen using a camera underwater.

This latest service for replacing all zincs, checking hull condition and general cleaning of items was $250. This is max cost I will expect as all zincs aren't replace every time during each diver service.... only replace a zinc if it's at 50% or less.

People installing GIs will to some extent expect a benefit given that've put down money and likely will want to express a benefit. For me I had two years of zinc replacement data prior to installing the GI and after the GI installed I compared zinc replacements against the 2 years without having the GI and found there too be no significant change in how often the zincs needed to be replaced.... and the boat was in same slip and same marina and neighbor boats did not move out.... so I think I had a good comparison for having the GI vs. not having the GI. I really do think my marina is 'hot' or that some boats around me are the culprits for my zincs eroding so quickly.
 
For whatever it’s worth, I had my boat for over a year in Washington state but it was on a trailer in between for much more time than in the water. While the zincs were used up in the water, there was an even greater loss of zincs out of the water to the point that I found zinc debris (zinc rust) inside the bowthruster tunnel and on the ground under the prop. The boat was always washed off after use and stored on trailer under cover near Seattle.

I think the factory puts different Zincs on depending on your main use location salt versus fresh (correct me if I am wrong). There haven been discussions here on the type of zincs best used based on water type and if in water permanently or not.
 
A galvanic isolator is for the protection of your boat when you are connected to shore power and only if the potential difference is not greater than 1.4 volts. Also it does not protect for any wiring issue on your boat. If it was my boat and my zincs were deteriorating fast I would get a marine electrician to help analyze my problem. It cost significantly less for a couple hours of the electrician time than for a O/B lower unit or a prop and/or shaft.
 
dclagett":2agl4tc2 said:
A galvanic isolator is for the protection of your boat when you are connected to shore power and only if the potential difference is not greater than 1.4 volts. Also it does not protect for any wiring issue on your boat. If it was my boat and my zincs were deteriorating fast I would get a marine electrician to help analyze my problem. It cost significantly less for a couple hours of the electrician time than for a O/B lower unit or a prop and/or shaft.
Click to expand...

That sounds like good advice for sure. What I will be doing is to ask my diver service with all their servicing data to tell me if they consider my case to be excessive/severe compared to other like boats they service, and they service a lot of boats in my PNW area and in the same marina my boat is kept at. If they indicate it is excessive/severe/unusual I will enlist the help of a 'marine electrician' to help analyze the issue.

One other thought I've had is to understand/confirm if my boat can 'survive' not being on shore power for say a week, and if so disconnect the boat from shore power every other week and see if the underwater zincs respond with less erosion, and hopefully, by a factor of 2x. 🙂

Thank you for your advice. 🙂
 
Now you got me scared.
I just deliver last month of New R27OB.

Dennis
 
Just changed my zincs today at 1450 engine hours. Boat is trailered in and out of salt water a couple of time a week. Using engine hours and a few hours at the ramp plus a few hours anchored up fishing, I would estimate that it would be the same time as if it was 70 to 80 days in the water. The prop zinc was deteriorated more than the other two. After removal I dipped the prop zinc in a muriatic acid bath for a couple of minutes to remove the crap and was surprised to see how badly it was eroded away. Couple of photos in my album. Don't know how to provide the link to the album.
 
I just received feedback from my diver service.... and it seems my zinc erosion is not unusual... 😱 and also it seems unhooking from shore power periodically can lengthen the zinc's life span. 🙂 So I will start doing the 1 week on shore power and one week without shore power to see what the benefit I get from doing this. This also will be much better that investing in a GI device IMO.

Hi Barry,

The corrosion is not excessive. A six month schedule for this set up is actually quite good.
The average for any boat at Edmonds is 4-6 months with a small percentage at 8-12 . And others on 3 month cycles....

We do have some clients whom unhook shore power for time periods and it does seem to lengthen the zinc life.

Hope this helps?

Have a good weekend!
Thank you,
Janel
 
https://www.cruisingworld.com/how/one-cool-remedy-galvanic-isolators

This link is to an article that explains why your good zincs can break down from protecting your neighbors' boats - since all plugged in boats share a common ground wire that DC current can move through... So a galvanic isolator may yield great benefits in one situation and no benefit in another...
 
At this point as I keep the boat in the salt year around I just factor zinc replacement by diver into the running costs every 6 months. its cheaper than a new prop!
 
Hmmmm.... come to think of it.... Surely, all I have to do is to have shore power connected for a day to charge and top up the batteries. Assuming this works I can keep shore power disconnected for most of the time and only connect it for one day after being off for a week. So on a per month basis this would mean having shore power connected for a total of 4 days.

I say this as the other day after shore power had been off for a week I connected shore power and within an hour the battery charger stopped its charge cycle. I determined that from the sound the battery charger makes when its charging.
 
I think you are only getting the bulk charge when you hear the noise from the charger. To get the last 20%, the charger rate drops and it takes a lot longer to finish like overnight. I wouldn’t want to only bulk charge batteries for long.
 
OK.... so overnight charging should do the trick, right ?
 
Barry, hi
My Cutwater 30cb is on Edmonds marina Q dock. Can you recommend a diver service?
Thanks Bob Gold
 
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