Is a little corrosion normal?

[Thalasso]

Re: Is a little corrosion normal?

Mercruiser is owned by Mercury but show me a Mercury OB with dual props hanging. The extra stainless changes things. If you want go do your research on what the factory recommends. For freshwater the only recommendation is MG with the b3. With the b2 and b1 AL is allowed but still MG is recommended.

Now that your mixing apples and oranges, the op is talking about a I/O If that helps you.

OMC OMC filed for bankruptcy 22 December 2000. So much for that argument

The Johnson and Evinrude brands were won by bid in February 2001

 

[thumpar]

Re: Is a little corrosion normal?

Now that your mixing apples and oranges, the op is talking about a I/O If that helps you.

OMC OMC filed for bankruptcy 22 December 2000. So much for that argument

The Johnson and Evinrude brands were won by bid in February 2001

Exactly. Why bring up what OB manufactures put on or recommend in the first place?

 

[UncleWillie]

Re: Is a little corrosion normal?

...Question being: Is this normal, or is this this indicative of a problem that could chew up my entire out drive after a year or so again?

Is a little corrosion normal?

A little corrosion is normal.
But what you have is NOT a Little Corrosion!
The lower unit is blistering Paint right off the drive!
The painted areas should still be solid black and spotless.
The bare Aluminum Props should have just a minimum amount of "chalk" on them.

The easiest way to test your, and your neighbor's, shore power for leakage is to place a clamp on Amp Meter on the shore power cables going to the boats.
If it reads Anything other than absolute Zero, there is a major problem.
Even a reading of 0.1 amps could be fatal and will destroy a lot of hardware in a short time. :grumpy:

 

[Thalasso]

Re: Is a little corrosion normal?

What UncleWillie said is a good way to check. Or place the positive end of a multimeter on the item in question and should read 0. I do this every so often. A galvanic isolator should help in this situation.

 

[QC]

Re: Is a little corrosion normal?

Sorry guys, off season, and snoozing. Moving to Merc I/O . . .

 

[KnotConnected]

Re: Is a little corrosion normal?

Hey guys,

Thanks for all the help and support.

Question: I do have a Mercathode system, and have verified that the controller on the engine has power and ground (even when the batteries are turned off). I've traced the other two wires down through the transom, but I'm not sure how to actually TEST the cathode, other than using Merc's testing steps by placing the doo-da in the water hooked to my multi-meter and start flipping switches. Ideally I'd like to test and verify the system is working BEFORE I plop it in the water, for obvious reasons..


So far my take-away's are:

1) This type of corrosion sure as hell isn't normal.

2) Install the prop-nut anode. This is a 1994 and didn't come with the Prop Nut Anode, so I'll need to buy the adapter, but if it'll save me $5,000 for a new outdrive, I'd gladly invest in one.

3) I'm not sure if I have a galvanic isolator installed. I've pulled the breaker panel off and haven't seen anything behind it, but I'm to the point where I'm willing to pay a pro to come in and look for one / install one if necessary. I _really_ don't want to have to replace this newly rebuilt lower unit or the entire outdrive after a years use.

 

[lg260ss]

Re: Is a little corrosion normal?

They have stainless.The only difference between the SX and the DPS is one has dual props. That's the only diff. Did you bother to look at or read the articles. I would think these people are a little more knowledgeable in the field then you or i. I didn't say i recommenced one over the other either. Look at the electrical scale diff between aluminum and Mag. there isn't much difference. .2 or 3 tenths

Fact: Merc Alpha and Volvo SX come standard with aluminum props.
If you think that hanging an extra 20lbs worth of stainless steel on your sterndrive (DP vs SX with a stainless prop or 40 lbs of stainless vs aluminum) makes no difference to galvanic corrosion, well you're wrong. BOTH MERC AND VOLVO RECOMMEND MAGNESIUM ANODES IN FRESH WATER. Please explain why they recommend something that makes no difference? Why do you think most modern water heaters use Magnesium anodes in lieu of aluminum? Have you ever owned a duoprop drive? I have owned 3 (1 merc and 2 volvos), all of which had no corrosion issues after switching to magnesium anodes. Unlike the others in my marina with aluminum anodes and drives that look like the OP's.
If you are referring to the article you posted? I do not trust articles written by a company pushing aluminum anodes. Also, that article says very little about freshwater boating. That .2 or .3 difference is about 25% BTW.

Here is an article for you to read: Sacrificial Anodes for Corrosion Protection in Underwater Metal

 

[lg260ss]

Re: Is a little corrosion normal?

Hey guys,

Thanks for all the help and support.

Question: I do have a Mercathode system, and have verified that the controller on the engine has power and ground (even when the batteries are turned off). I've traced the other two wires down through the transom, but I'm not sure how to actually TEST the cathode, other than using Merc's testing steps by placing the doo-da in the water hooked to my multi-meter and start flipping switches. Ideally I'd like to test and verify the system is working BEFORE I plop it in the water, for obvious reasons..


So far my take-away's are:

1) This type of corrosion sure as hell isn't normal.

2) Install the prop-nut anode. This is a 1994 and didn't come with the Prop Nut Anode, so I'll need to buy the adapter, but if it'll save me $5,000 for a new outdrive, I'd gladly invest in one.

3) I'm not sure if I have a galvanic isolator installed. I've pulled the breaker panel off and haven't seen anything behind it, but I'm to the point where I'm willing to pay a pro to come in and look for one / install one if necessary. I _really_ don't want to have to replace this newly rebuilt lower unit or the entire outdrive after a years use.

When you pulled the boat, did the anodes look like they have corroded at all? If not, you probably have aluminum or zinc anodes and they are the wrong anode for your application.

 

[Thalasso]

Re: Is a little corrosion normal?

Fact: Merc Alpha and Volvo SX come standard with aluminum props.
If you think that hanging an extra 20lbs worth of stainless steel on your sterndrive (DP vs SX with a stainless prop or 40 lbs of stainless vs aluminum) makes no difference to galvanic corrosion, well you're wrong. BOTH MERC AND VOLVO RECOMMEND MAGNESIUM ANODES IN FRESH WATER. Please explain why they recommend something that makes no difference? Why do you think most modern water heaters use Magnesium anodes in lieu of aluminum? Have you ever owned a duoprop drive? I have owned 3 (1 merc and 2 volvos), all of which had no corrosion issues after switching to magnesium anodes. Unlike the others in my marina with aluminum anodes and drives that look like the OP's.
If you are referring to the article you posted? I do not trust articles written by a company pushing aluminum anodes. Also, that article says very little about freshwater boating. That .2 or .3 difference is about 25% BTW.

Here is an article for you to read: Sacrificial Anodes for Corrosion Protection in Underwater Metal

Two for you . I never said which anode you should or shouldn't be using but aluminum is ok in place of Mag.
http://www.performancemetals.com/images/anodes/ABYCrec.jpg

Initially the anodes for these units were made of zinc, but in response to corrosion problems, Mercury and Johnson/Evinrude/OMC started selling the aluminum anodes in the early 1990’s. Other manufacturers are switching to aluminum too. The small increase in protective voltage helps ensure that the sterndrive is protected. If you use zinc anodes you may even invalidate your warranty! Again, be careful using magnesium anodes since you can overprotect your stern drive or outboard.

Where possible Navalloy™ (aluminum/zinc/indium alloy) anodes are recommended over zinc. Zinc anodes can become inactive after only a few months due to the build up of an insulating film of zinc hydroxide. Aluminum anodes will remain active. Don't take our word for it though, ABYC (American Boat and Yacht Council), who set the standards for the industry, clarified their recommendations on anode materials in the Standards and Technical Information Reports for Small Craft (July 2008-2009):

As you can see, the only anode type that is recommended for all water types is aluminum (Navalloy).

How can Navalloy™ (aluminum) anodes protect aluminum out drives?
Because the Navalloy™, aluminum anode is a combination of aluminum, zinc and indium. It is like comparing steel and stainless steel - they have very different properties. The zinc and indium make the metal more active and prevent the anode from forming an oxide coating.

 

[thumpar]

Re: Is a little corrosion normal?

I would trust the manufacturer. http://www.boatzincs.com/pdfs/Which_Anodes_Should_I_Use-Chart_Merc-A.pdf

 

[Thalasso]

Re: Is a little corrosion normal?

Hey guys,

Thanks for all the help and support.

Question: I do have a Mercathode system, and have verified that the controller on the engine has power and ground (even when the batteries are turned off). I've traced the other two wires down through the transom, but I'm not sure how to actually TEST the cathode, other than using Merc's testing steps by placing the doo-da in the water hooked to my multi-meter and start flipping switches. Ideally I'd like to test and verify the system is working BEFORE I plop it in the water, for obvious reasons..


So far my take-away's are:

1) This type of corrosion sure as hell isn't normal.

2) Install the prop-nut anode. This is a 1994 and didn't come with the Prop Nut Anode, so I'll need to buy the adapter, but if it'll save me $5,000 for a new outdrive, I'd gladly invest in one.

3) I'm not sure if I have a galvanic isolator installed. I've pulled the breaker panel off and haven't seen anything behind it, but I'm to the point where I'm willing to pay a pro to come in and look for one / install one if necessary. I _really_ don't want to have to replace this newly rebuilt lower unit or the entire outdrive after a years use.

If you find the green (ground wire) in your elec panel, the galvanic idolater is connected to it and then the green continues on to the buss bar. To check polierzation you need a Silver Chloride tester.

Corrosion Reference Electrode Product Specifications
Corrosion Reference Electrode Product Specifications
One end (red) gets plugged into the MM and the other end goes to ground (batt) You drop it down 6 inches behind your drive and the reading on the MM should be anywhere from 950-1150. What the Mercathode does is polarizes the area around your drive. Water current and makeup can effect this reading. If it is too low get yourself another controller. It has to be the same color as the one you have. I think there is four wires on your current one. just put another wire from one to the other corresponding screw and mount er up.

Your system should always be energized that's why you need to have a battery charger. It will kill the batteries.

 

[KnotConnected]

Re: Is a little corrosion normal?

I figured you might ask that!

I Bolted up new anodes before I put'er in the water this past season, and just looked up the receipt to verify they were indeed MG. I've since replaced them with fresh anodes for this coming season, but took some pics of the old ones before I 86'd 'em.

http://i46.photobucket.com/albums/f117/n915aa/IMAG1206_zpsd979a60c.jpg
http://i46.photobucket.com/albums/f117/n915aa/IMAG1207_zps06deb333.jpg
IMAG1204_zpsfe256d41.jpg Photo by n915aa | Photobucket

 

[thumpar]

Re: Is a little corrosion normal?

WOW. Those look really bad. I think you may has some issues with the shorepower.

 

[tpenfield]

Re: Is a little corrosion normal?

Compared to what I am used to seeing with salt water, those anodes do not look too bad. . . It seems that the outdrive might have taken more of a 'beating' than the anodes :noidea:

One thing that I did this past season in terms of corrosion protection, which seemed to work fairly well, is that I painted the dual props with Cold Galvanizing compound (3 coats)

Having a 'weak' metal directly on the stainless steel seemed to help avoid corrosion around the prop hub that was happening to my outdrives in the past . . . similar to what you (the OP) are seeing after your 1 season.

Here is a picture of the outdrives/props after a bit of power washing.

 

[lg260ss]

Re: Is a little corrosion normal?

I figured you might ask that!

I Bolted up new anodes before I put'er in the water this past season, and just looked up the receipt to verify they were indeed MG. I've since replaced them with fresh anodes for this coming season, but took some pics of the old ones before I 86'd 'em.

http://i46.photobucket.com/albums/f117/n915aa/IMAG1206_zpsd979a60c.jpg
http://i46.photobucket.com/albums/f117/n915aa/IMAG1207_zps06deb333.jpg
IMAG1204_zpsfe256d41.jpg Photo by n915aa | Photobucket

Those anodes are doing their job and look fine. That is what they should look like after 6 months. Be sure to get a propshaft anode, it will help. This is the reason why merc added the propshaft anode and 1 additional pancake anode to the cavitation plate in 2004. As others have suggested, you need to check to make sure your Mercathode is working. I will try to find an article I read that suggested running 2 mercathodes in parallel to increase protection. Do you have trim tabs? Are they stainless, and do they have anodes? Have you seen the outdrives of any of your dock neighbors? Are they having the same issues? If it is just your boat, it is much easier to isolate the issue.

 

[KnotConnected]

Re: Is a little corrosion normal?

Those anodes are doing their job and look fine. That is what they should look like after 6 months. Be sure to get a propshaft anode, it will help. This is the reason why merc added the propshaft anode and 1 additional pancake anode to the cavitation plate in 2004. As others have suggested, you need to check to make sure your Mercathode is working. I will try to find an article I read that suggested running 2 mercathodes in parallel to increase protection. Do you have trim tabs? Are they stainless, and do they have anodes? Have you seen the outdrives of any of your dock neighbors? Are they having the same issues? If it is just your boat, it is much easier to isolate the issue.

-okay, so...
i *suppose* it's worth mentioning, that i DID put her up on a sand bar this previous summer. I was pretty good and stuck, but was able to push it out a bit and power the rest of the way out (we had gone from about 15 to *stopped* in a hurry). Could this be damage from that, rather than corrosion? or could the corrosion be caused by damage from that? (paint being scraped off, etc?)

-All of my neighbors are sailboats with outboards, or inboards, but I haven't seen them (they all store elsewhere in the winter). However, this issue started before I had the boat in this slip, so i *do* think it's my boat.

-I do have stainless trim tabs, and they don't have anodes.

-I've heard of adding a 2nd or 3rd MerCathode to the system, but am not sure how or where it'd go, as the cathode right now is connected to the outdrive under the trim pump collection block (improper terminology?). I've got the pro at the marina looking into the existence of a galvanic isloator right now. I'll also do some digging for some how-tos on multiple MerCathodes, but if you have any pointers or know of a good article it'd always be appreciated.

 

[lg260ss]

Re: Is a little corrosion normal?

-okay, so...
i *suppose* it's worth mentioning, that i DID put her up on a sand bar this previous summer. I was pretty good and stuck, but was able to push it out a bit and power the rest of the way out (we had gone from about 15 to *stopped* in a hurry). Could this be damage from that, rather than corrosion? or could the corrosion be caused by damage from that? (paint being scraped off, etc?)

-All of my neighbors are sailboats with outboards, or inboards, but I haven't seen them (they all store elsewhere in the winter). However, this issue started before I had the boat in this slip, so i *do* think it's my boat.

-I do have stainless trim tabs, and they don't have anodes.

-I've heard of adding a 2nd or 3rd MerCathode to the system, but am not sure how or where it'd go, as the cathode right now is connected to the outdrive under the trim pump collection block (improper terminology?). I've got the pro at the marina looking into the existence of a galvanic isloator right now. I'll also do some digging for some how-tos on multiple MerCathodes, but if you have any pointers or know of a good article it'd always be appreciated.

Here are a few articles directly from the manufacturer.
http://www.marinemechanic.com/merc/distributors/mercurymarine/sterndrive/corrosiontesting.PDF
http://www.google.com/url?sa=t&rct=...6810SovjfNKxPWv_mKpG0OA&bvm=bv.60157871,d.cWc

The second one is very informative and gives wiring diagrams on how to add a second mercathode. Apparently adding a second mercathode is only for salt water use but they give options for increasing the protection in fresh water too (page 12-13). These articles came out between 2002 and 2004 when Merc had finally admitted that they had a problem with corrosion and the Bravo 3 drive.

If you did scrape the paint off the skeg then I would expect some corrosion, especially when you do not have the anode on the propshaft. BTW, the second article also shows a diagram of the retrofit kit for the propshaft anode on page 7.

 

[Thalasso]

Re: Is a little corrosion normal?

goastnode.

Check again for a galvanic isolator before doing anything else.

If you add another mercathode system you will likley be drilling holes in the stern to mount what looks like hockey pucks and the wire runs through the transom. Look at the illustration on page 13 at the stern.


The below also works in fresh water.

In Salt Water
: Add another MerCathode System
controller, wired in parallel (Figure 2-22). (The additional
MerCathode controller must be of the same
type as the original one; i.e., black plus black or blue
plus blue.) This will double your protection to 400 mA.
(Keep in mind that this will also increase the drain on
your battery.) If you take your boat into fresh water,
the conductivity of the water will limit the output of
your MerCathode Systems.