Freshwater Prop Anode Info Needed

[LuvBoating]

We have a 1992 20' Celebrity Cuddy Cabin. Have had this boat since April 2009. From what we know, it has never been in freshwater. Originally from Washington State and used on a Puget Sound there and then brought here to Jacksonville, FL. The water here is "brackish", combo of salt/fresh.

The boat is being transported to Colorado, because we are moving back there. When I mentioned about changing the anodes to our marine service, the office manager told me they had a magnesium Kit that a customer didn't want. It's a Quicksilver Anode Kit for a 1991 and newer Alpha One Gen II. It came with six anodes.

I found the invoice, from 2016. of our transom assy. repair and it states the drive is a Alpha One Gen II.

The mechanic that put these new anodes on, told me that the prop area didn't have one in it and no holes to secure one. So, we got that one back, along with the 5 used ones.

Do all props need an anode or just some of them? Couldn't find any online info saying some don't.

 

[alldodge]

Do all props need an anode or just some of them?

Props do not need anodes, but drives do. The one behind the prop is more anodes for the drive. The issue with an anode behind the prop deals with if one can be installed. The drive design changes over time and yours does not have the ability to install one, so none can

 

[LuvBoating]

Then, I wonder WHY one was included with the Kit?

 

[Bondo]

Ayuh,..... Probably because "Kits" usually fit multiple applications,.....

 

[LuvBoating]

Ayuh,..... Probably because "Kits" usually fit multiple applications,.....

Ok. It does say on the box "1991 and newer" and ours is a 1992.

Question is, if there is an anode for the prop shaft for some, why aren't there for others? Doesn't the prop area have to be protected just like the rest of the outdrive? Although, now going into freshwater, we don't need the protection like when the boat was being put into salt and "brackish" water.

 

[Bondo]

if there is an anode for the prop shaft for some, why aren't there for others?

Ayuh,.... Ask the engineers at Mercruiser,......

 

[alldodge]

Most changes come from something not working good enough or other problems arise. Galvanic corrosion is a large problem for the marine environment, boating, Navy, etc. Anodes where installed and later found that more were needed in some cases.

The more stainless that is added to a drive, the greater need for stronger Mercathode currents and more anodes. The B3 in later designs added one to the end of the prop shaft

 

[LuvBoating]

Props do not need anodes, but drives do. The one behind the prop is more anodes for the drive. The issue with an anode behind the prop deals with if one can be installed. The drive design changes over time and yours does not have the ability to install one, so none can

The anode doesn't go on the prop itself, but on the shaft behind the prop. Mechanic to me that there wasn't one there and no holes to screw one on. So, that anode was given back to us.

So, the area behind our prop, on the shaft, doesn't use one or need one. That area doesn't have to be protected or there would've been one there.

 

[alldodge]

So, the area behind our prop, on the shaft, doesn't use one or need one. That area doesn't have to be protected or there would've been one there.

Yes and no
Yes, the more protection the better
No, your drive was not manufactured to use it, but your also in fresh water so the drive will not need it as much

The prop should be removed doing yearly maintenance and inspected, grease the shaft and reinstall

UPDATE
Just looked at all Gen 2 drives and everyone of them including yours (1992) should have the place to install the anode. So from 1991 thru current date they all show it in the parts list (item 56A).

https://www.mercruiserparts.com/bam/.../30858/1017/90​​​

Would like to double check with someone like muc in case there were some manufactured without

Take the prop off and see if there are screw holes and maybe the shop just didn't want to install

 

[achris]

...UPDATE
Just looked at all Gen 2 drives and everyone of them including yours (1992) should have the place to install the anode. So from 1991 thru current date they all show it in the parts list (item 56A)....

That's my experience as well.

It may be that an previous mechanic decided that it was 'too hard' to remove the prop and install an anode, and the boat was fresh water anyway and never bothered to install it. Even so, the mounting holes WILL be there. They may be clogged with crud, but cleaning them up will enable an anode to be installed in place.

Chris....

 

[muc]

My memory says that the first years of the Gen2 didn't have trim ram or bearing carrier (in front of prop) anodes. But my memory ain't so good on stuff like this.
Are we sure this is the original gear case? If this boat has sat in saltwater since 1992 it might not. Is it an SEI? Don't know if SEI has mounting for a anode on the bearing carrier.

Why don't you pull the prop and look?

More anodes were added to drives over the years because the EPA forced the manufactures to change the paint.

It's highly possible you don't need this anode. Does the boat have an Mercathode system on it?

Somebody said more anodes is better. That's not correct. Too much anode is worse than not enough.

Only way to find out is get an reference electrode and check the current.

 

[alldodge]

Somebody said more anodes is better. That's not correct. Too much anode is worse than not enough.

I'm sure your correct but have never heard this, where can I find the info on this?

 

[dingbat]

I'm sure your correct but have never heard this, where can I find the info on this?

https://www.practical-sailor.com/blo...s-12130-1.html

https://cdn.shopify.com/s/files/1/2245/5025/files/Corrosion_print.pdf

 

[alldodge]

Good info, thanks

Now need to understand the differences between the postings and Merc corrosion manual

http://www.boatfix.com/merc/Techbk/97/97hs7.pdf

Merc says for fresh water and mercathode mounted on the bottom of the transom assembly, readings should be
620 - 1180 Millivolts with Digital Meter

http://assets.fluke.com/appnotes/electricalpower/B0269b_u.pdf

Fluke manual appears to be listing protection for each hull material and not glass with an out drive. That said the readings are similar



The testing above is to connect negative probe to each fitting and then measure reading using Silver-Silver
Chloride. probe. Have used my probe many times to check and always though the more the merrier, From now on I will look at it with a different view.

Before my last repower I had trouble getting the voltage up to within range, and installed a different mercathode

 

[achris]

I used to be 3.4U qualified (senior inspection engineer, in oil and gas), and a big part of that course is CP (Cathodic Protection), and I can state that 'over' protection is very bad.

If you have a glass boat, use the material of the drive and transom housings, usually aluminium....

Chris.....