Diver said prop has pink hue

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Thanks. I ordered an aluminum grouper and will deploy it soon, when I get back to the boat in a week or so.

Also have a new galvanic isolator coming that I will install.

Also got some good info how to check my various items connected to the bonding system with my silver half cell that I have on the boat (but have never used).

Thanks for all the ideas!
 
Jack Balkenende said:
So to find the isolator I would look on my incoming AC and it'll be in there between that and my panel correct
Click to expand...

Look at the green wire coming in from the shore inlet and follow it to the electrical panel. Somewhere in that run you should find the isolator.
 
Boat completely unplugged from AC dock power. Absolutely isolated DC batts on board.

Open, screened, curtained windows in spring, summer, fall and slightly cracked windows during rainy season.

Works wonders keeping my boats' metals in good condition, for relatively slow deterioration of anodes and continued fresh interior order.

Simple is as simple does!
 
Alisske said:
Ive seen bad de-zincification in the yard. Owner would ask “why is my prop pink?!?” I would just give a Good hit to one blade with the palm of my hand and the blade would brake off.

Additionally, i had a boat for a decade. Used half a zinc a year. Brought it to a buddies house to use his lift to do work.

Changed the zincs while she was up. Had it in the water 3 weeks there. The new zincs were eaten up in 3 weeks. Was stray current from dock wiring.

If you were somewhere new, stray current is a bitch

Amazing the owner would thank me for breaking his prop, lmao.

Maybe not so in your case, but definitley check.
Click to expand...

A friend cruised his boat to Fl from Ct one year. Put the boat at a marina somewhere in Florida.
Went back a month later and dove to check his zincs. When he grabbed a prop to pull himself to the shaft he ended up with a piece of his prop.
Totally gone in 30 days. He had the boat hauled that day.
 
jleonard said:
A friend cruised his boat to Fl from Ct one year. Put the boat at a marina somewhere in Florida.

Went back a month later and dove to check his zincs. When he grabbed a prop to pull himself to the shaft he ended up with a piece of his prop.

Totally gone in 30 days. He had the boat hauled that day.
Click to expand...
I will re-post Steve D's article. Buried in it is a discussion on stray current which can be destructive at a very rapid pace such as your friends. d'Antonio dispels the "hot marina" myth and states this type of rapid degradation is due to onboard DC problems.

https://stevedmarineconsulting.com/unraveling-the-corrosion-mystery/

Peter
 
First, I'd go to aluminum and never use zincs again anywhere.

As to the marine electrician you need, the only place I would expect to find them in the area of your boat would be Seabrook but I haven't used them for such.
 
Rapid metal loss is almost always due to DC current. We bought a boat that had 50+ volts AC flowing in the bilge due to the PO replacing the shore power inlet and switching the white and green wires. There wasn’t any metal loss.
 
Comodave said:
Rapid metal loss is almost always due to DC current. We bought a boat that had 50+ volts AC flowing in the bilge due to the PO replacing the shore power inlet and switching the white and green wires. There wasn’t any metal loss.
Click to expand...

How long was that wire configuring present? Did the PO do so just before you purchased as he made ready for sale? Had the boat much time "Plugged in" with wires crossed?
 
It was like that when we bought it. The PO was out of the area so it was like that for quite a while. Yes it was plugged in. It had current flowing in the bilge, but it was AC. If it had been DC then there would have been severe metal loss.
 
Art said:
Boat completely unplugged from AC dock power. Absolutely isolated DC batts on board.



Open, screened, curtained windows in spring, summer, fall and slightly cracked windows during rainy season.



Works wonders keeping my boats' metals in good condition, for relatively slow deterioration of anodes and continued fresh interior order.



Simple is as simple does!
Click to expand...


I find this interesting, leaving the boat unplugged from shore power when away. How many do this?

If, as the D’Antonio article suggests, almost all corrosion problems are from DC power leakage, what does disconnecting the boat from AC get you?

The only things that runs off of AC when away on my boat are the large house size dehumidifier, three fans and the battery charger. I’m wondering if I could switch to DC fans and a smaller peltier style DC dehumidifier and also be totally off grid.

I only have 340 watts of solar and a 500ah 12v battery bank however, so not sure that’s enough to keep up. The dehumidifier I’m looking at is an Eva Dry 2400 that runs off 6 amps at 12v. I have two fairly efficient Caframo DC fans on board I could also use I suppose. They use about .4 amps each per hour, so a total draw of 6.8 Amps for everything? That’s 36 hours of runtime (250 AH usable battery capacity divided by 6.8 ah usage). Did I do that right?

36 hours does not seem doable to me. If I get one cloudy day my batteries will go under 50%.
 
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Only thing I do when leaving is turn off the fresh water pump. Boat stays plugged in, fridge and AC on, etc. I figure if I can't trust my own systems unattended for a few days, I need to fix them.
 
rslifkin said:
Only thing I do when leaving is turn off the fresh water pump. Boat stays plugged in, fridge and AC on, etc. I figure if I can't trust my own systems unattended for a few days, I need to fix them.
Click to expand...


Agree. I just need to fix my systems so I don’t have to worry.
 
rslifkin said:
Only thing I do when leaving is turn off the fresh water pump. Boat stays plugged in, fridge and AC on, etc. I figure if I can't trust my own systems unattended for a few days, I need to fix them.
Click to expand...

Instead of your wonderful capability to only leave your boat "... unattended for a few days..."

With our boat having been docked 100 miles away for 13 years [under covered dock] there have been some extended periods of no-visit, especially in winter months.

During last few years... between... covid-19 jumble and some severe health troubles our visits became ever more sporadic. One extended 9 months between visits.

Sooo... In following the rules-of-thumb for leaving boat in water unattended I was brought up to understand [i.e., trained by dad and shipwrights in NY boatyards when young] was to disconnect from shore power and isolate batteries - That's what I do. What I know from experience is that by keeping bilge completely dry, isolating all batteries with Pergo master switches and off-hooking from shore power as well as keeping anodes well serviced and screened windows at least on a crack - in over five decades of caring for boats I've never had a loss due to corrosion of metals on any of my boats. 50 + years with no metal loss - yeah, I'll buy that!

Now that we this month cruised our Tolly 85 miles to be in a dock just minutes away I will be to visit her much more often [love being able to do that!]. The 13 years of having played with her 100 miles away means she needs a good amount of cosmetic assistance. Planning to put a worker from my const co on the project of complete simonize as well as other clean-up agenda. I'm gonna spend some time aboard also doing cleaning/shining... as well as some item/product repairs.

We may and may not sell her... health is improving... but, years are still gaining!

More will be revealed! :dance: :speed boat:
 
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cardude01 said:
I find this interesting, leaving the boat unplugged from shore power when away. How many do this?

If, as the D’Antonio article suggests, almost all corrosion problems are from DC power leakage, what does disconnecting the boat from AC get you?

The only things that runs off of AC when away on my boat are the large house size dehumidifier, three fans and the battery charger. I’m wondering if I could switch to DC fans and a smaller peltier style DC dehumidifier and also be totally off grid.

I only have 340 watts of solar and a 500ah 12v battery bank however, so not sure that’s enough to keep up. The dehumidifier I’m looking at is an Eva Dry 2400 that runs off 6 amps at 12v. I have two fairly efficient Caframo DC fans on board I could also use I suppose. They use about .4 amps each per hour, so a total draw of 6.8 Amps for everything? That’s 36 hours of runtime (250 AH usable battery capacity divided by 6.8 ah usage). Did I do that right?

36 hours does not seem doable to me. If I get one cloudy day my batteries will go under 50%.
Click to expand...

Almost all corrosion is DC in nature, but the minority is from stray current, i.e. a battery, the rest is galvanic, which is dissimilar metal based. Unplugging separates your vessel's bonded underwater metals from other vessel's bonded underwater metals, and prevents your anodes from protecting the underwater metals of those other boats, which again is galvanic corrosion. But, you can achieve the same goal using a galvanic isolator or shore power isolation transformer, which I recommend.

A 'pink prop' is the result of dezincification, it usually occurs as a result of not frequent enough anode replacement (or using the wrong anode material), the zinc in the manganese bronze (many props are made from manganese bronze, which is in fact brass) is being sacrificed to protect the copper. That corrosion phenomenon is covered here https://stevedmarineconsulting.com/know-your-underwater-alloys/

If you are on a lake, as others have noted, you need to use aluminum anodes.

Underway, Elovoi Islands, AK
 
Green wire

The reason the plugged in shore power matters is that the green wire ground gets connected to the DC negative of your system. any stray dc current in the water can use this as a return path causing rapid wasting on your boat. A properly functioning galvanic isolator will prevent this.
 
Mmfitzpatrick said:
The reason the plugged in shore power matters is that the green wire ground gets connected to the DC negative of your system. any stray dc current in the water can use this as a return path causing rapid wasting on your boat. A properly functioning galvanic isolator will prevent this.
Click to expand...

Yes - And, simple, cost free unplugging from shore power guarantees to prevent it! :thumb:
 
Test your boat first!

I think a poor connection on your shore cord defeated the galvanic isolator and allowed DC current to come through. Before you change anything test your galvanic isolator and hull potential. You mentioned you have a silver chloride half-cell. It is easy to use, and the GI test is straightforward, but both require an AC/DC multimeter.

Promariner GI manual attached, and boatzincs.com has information about using its silver chloride half-cell here:

https://www.boatzincs.com/corrosion-reference-electrode-specs.html

I bet your boat is fine!
 
I have a new isolator I need to install, but we had a family emergency and I have not been able to make it back to the boat.

Thank you for all the thoughtful suggestions.
 
Mmfitzpatrick said:
Agreed. But galvanic isolator should be mandatory, you're going to be plugged into shore power sometimes.
Click to expand...

When you say "mandatory" in all boats... by law!!??? I don't agree with that :facepalm: Or mandatory by new boat builders! That could be ok - I guess :ermm:

For me having boated since birth [I'm 70 now] neither anyone in my family nor I ever leave our boats plugged into shore power AC. And, we seldom if ever have boat plugged in for more than a few hours while readying to leave slip or for returning to slip for offloading.

Far as I'm concerned: No connection to dock AC is foolproof! Make sure your boat does not leak... and... for any worst case scenario that might happen have good ins coverage paid up!
 
Mmfitzpatrick said:
The reason the plugged in shore power matters is that the green wire ground gets connected to the DC negative of your system. any stray dc current in the water can use this as a return path causing rapid wasting on your boat. A properly functioning galvanic isolator will prevent this.
Click to expand...

Just to clarify, the common green safety ground used in the shore cord connects underwater metals, that leads to galvanic corrosion primarily, while it can lead to stray current corrosion as well, but that's less common.

Galvanic isolators do not block stray current (hence the name "galvanic" isolator), the voltage is too high, galvanic isolators work up to about 1.3 volts DC. Stray current, coming from the battery, is usually much higher.
 
If you have DC and AC aboard it is best to have the DC negative and AC green ground connected. If you don't, operate in freshwater, and stay in marinas using shore power you create an electric shock hazard in the water around your boat. If AC current finds its way on the DC side and has no path back to ground through your shore cord it will go into the water and find it and sometimes someone in its way. Saltwater is a very good conductor so people in the way are at very little risk.

Lots of information about this risk. Search the web for ESD (electric shock drowning).

Soo-Valley said:
If you isolate DC from AC would you still need a galvanic isolator?
Click to expand...
 
bglad said:
If you have DC and AC aboard it is best to have the DC negative and AC green ground connected. If you don't, operate in freshwater, and stay in marinas using shore power you create an electric shock hazard in the water around your boat. If AC current finds its way on the DC side and has no path back to ground through your shore cord it will go into the water and find it and sometimes someone in its way. Saltwater is a very good conductor so people in the way are at very little risk.

Lots of information about this risk. Search the web for ESD (electric shock drowning).
Click to expand...
Read my question again.
If you isolate DC from AC would you still need a galvanic isolator?
 
Soo-Valley said:
If you isolate DC from AC would you still need a galvanic isolator?
Click to expand...

You can't isolate AC safety ground and DC negative and still maintain the highest possible electrocution prevention on the boat, while leakage into the water and electric shock drowning is yet another matter. For ABYC compliance, AC safety ground, and DC negative must be common.

If you isolate and a piece of gear, a seacock for instance, was to become energized with AC current, it would sit there energized until a person touched it and something that was grounded, completing the path and leading to an electrocution.

More on the subject here https://stevedmarineconsulting.com/safe-shore-power-and-electrocution-prevention-2/
 
SDA, OK, but do you need an isolator if the DC and AC are not connected.
Yes I think in the abstract. The isolator is a needed add on because of the mandate to bond the two. One change requires another.
Hypothetically if the AC ground is not connected to the DC negative, would you need an isolator.
 
Everyone needs an isolator or an isolation transformer. The latter is heavy and expensive.

Or just leave your boat unplugged in the marina so when you want to go the engines won't start.

And don't forget to go through the bilge and fix the bad connects.

Yeah, this boat stuff is a lotta work - :)
 
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