Outdrive Corrosion

[src]

I recently pulled my 310 out for the winter, and found that the Bravo 3 outdrives are showing some heavy buildup on the skeg, and light buildup on some other areas. The reason I say "buildup" is that it mostly appears to be buildup on the surface, instead of pitting into the surface. I haven't started trying to clean it up yet, but I wanted to get some opinions from the group.

I had new anodes and anti-foul paint put on at the beginning of the season, but I think they may have used the wrong material. I've heard of Magnesium anodes "overworking" and causing an accumulative affect. I do not know whether they put aluminum or magnesium anodes on (although I specified fresh water use when I had them done). Obviously I'll be careful with what I replace them with next.

It spends 90+% of the time in freshwater - I'm very far up the James River, and we don't really get much/any salinity here. I did take it out to the Chesapeake Bay for a week in July, but that didn't "cause" this that I can tell.

In September I lightly scrubbed the drives down with soft brushes to take off some algae that had been growing, and at the time there was nothing like this on the drive, and the skeg was pretty clean.

I know that I have put the skegs into the mud a few times, so I'm sure I rubbed off the anti-foul and probably scratched the paint, but it seems odd for this to have shown up between early September and mid-November, when it was finally hauled.

One other factor is that before it was hauled, I had it in the shop's marina (not my home marina) for a few weeks. During that time, it was NOT hooked to shore power. Could this be from a current leak in the other marina?

 

[jason78]

How long have the anodes been on?

Also, do you have records with part numbers to find out if they are alum or magnesium? I have been told here before to never, for any amount of time, operate on brackish or salt with magnesium. That may be what happened if you have magnesium anodes.

 

[src]

How long have the anodes been on?

Also, do you have records with part numbers to find out if they are alum or magnesium? I have been told here before to never, for any amount of time, operate on brackish or salt with magnesium. That may be what happened if you have magnesium anodes.

The anodes went on in May, right before the boat splashed - it had been blocked for about 18 months before then. I don't have any information on what material they are. It just struck me as odd that I made it through September, including a week in salt, without any signs of this problem. Obviously something happened/changed after then. Scrubbing the outdrives and moving to the other marina for a few weeks were the only changes in routine that stood out in my mind.

At the time I cleaned the drives, there was pitting on the anodes, but they looked to be in decent shape overall.

 

[Dave S]

You can read this article with reference to the various types of anodes and what can happen if you use the wrong ones. http://www.defender.com/html/zincs_info.html

It is possible the boat has the correct magnesium anodes on it since you said there was no corrosion in September. But it is also possible your Mercathode has failed as well. The crusty white build up on the anodes themselves, such as what you show on the picture of the ram anode is not normal. Typically, in fresh water all you should see is pitting with none of that white stuff. Unfortunately, you can't really test the Mercathode system without being moored in the water.

 

[src]

Hmm, I wonder if being off shore power for several weeks ran the batteries down. I'll have to check the voltage next time I'm at the boat. Also, I think the battery switches were off. That might have turned the mercathode off according to something I just read.

 

[CV-23]

I have to keep after my Bravo1 and change anodes every year in fresh water! I use the Interlux paint for outdrives and it helps quite a bit. Also keeps all the slime growth off. It's a shame Mercury can't do better for what they cost, Mike.

 

[jason78]

Hmm, I wonder if being off shore power for several weeks ran the batteries down. I'll have to check the voltage next time I'm at the boat. Also, I think the battery switches were off. That might have turned the mercathode off according to something I just read.

If the wiring has not been altered, the Mercathode should function (or rather be powered) regardless of the position of the battery switches. As long as the batteries were connected and charged it should have been fine. If this is your original Mercathode system you may want to look in to replacing the controllers and definitely the Mercathode anodes that mount under the Gimbal ring as those tend to go bad after 4-6 years. While you are at it, check out the RED (Heavy Duty) Controller kits that include the transom pucks. They add extra protection. You may also want to consider adding a prop anode to each drive. That was an "enhancement" they made around MY03 to help further combat corrosion problems on the B3. You can get the Nut/Anode set at boatzincs.com and other sources.

 

[src]

Hmm, I thought mine had the transom pucks, but looking at another picture I see it doesn't. I'll certainly look at the upgraded systems, and also the prop zincs.

Any opinions yet on what I'm looking at regarding the corrosion in the pictures? Is it fairly typical, or am I overreacting?

 

[jason78]

Any opinions yet on what I'm looking at regarding the corrosion in the pictures? Is it fairly typical, or am I overreacting?

I dont think you are overreacting. In my opinion you need to do something, but that is by far not even close to the worse B3 I have seen. I think changing the Mercathode gimbal anodes, possibly the controllers and considering the RED controller upgrade with transom pucks is a good start along with adding the prop anodes. It is my belief that most of us with year-round slipped Bravo Three drives have come to accept that some corrosion is going to occur but with the right systems and maintenance you can keep it to a minimum and relatively "on the surface" and under control. I have even seen SeaCore Bravo Three drives with corrosion.

 

[ZZ13]

Your BIII drive doesn't really look any worse than any of the BIII drives pulled out after sitting in the upper Potomac River for 6 months. I incorrectly put Magnesium anodes on my BIIIs once for six months. Drive looked worse that time and the paint got worked off in spots. So stick with Aluminum anodes in your waters. Also, I found my mercathode pucks (I had five on the back of my 300DA) just didn't last long in the Potomac. After two years, 3 of the five had quit working.

 

[Nehalennia]

It's not build up, it's pitting and break down. Get on top of it now. You don't want to let it get any further. They'll end up looking like the OD that was on Nehalennia (which was replaced by the PO) when I bought her. The following was a $9800 problem for the PO.
At Survey






After I had the PO replace it

 

[Lazy Daze]

It takes time for the waters to warm up enough to become very active. So the continued warm water into the late Summer and early Fall is likely the reason that you saw the corrosion start to set in. Could of also been that the new area you were in was slightly more active.


Dragging the skeg through some mud/sand can certainly explain why you see more stuff on the skeg than anywhere else since the paint was removed. However (unless the picture is deceiving), the antifouling paint on the rest I the drive doesn't seem to be put on very well as it looks like it was applied somewhat scarcely.


The rest of the corrosion, for the most part, is limited to edges. Due to (even more so with a possibly inferior paint job) the fact that paint will typically be thinner on edges, that's pretty normal. Overall, doesn't look all that bad at this point and with a little elbow grease it will be just fine.


Check on the anode composition and use what experienced boaters from your area are using. Get your Mercathode system checked. Sand and repaint the drive and you'll be good to go.

 

[src]

Could of also been that the new area you were in was slightly more active.

the antifouling paint on the rest I the drive doesn't seem to be put on very well as it looks like it was applied somewhat scarcely.

The temporary marina was right on the James River, so I'm certain there was a lot more activity and current, which I have since learned reduces the effectiveness of the mercathode system.

Also, I think the anti-foul was put on fairly well (although I can't say for sure, but it looked good before we splashed) - I'm pretty sure that what you are seeing is due to scrubbing the algae off in September. I had someone else do most of the work on the drives while I did the hull, and I suspect he was overly aggressive on the use of force. That explains the apparent "brush strokes" you can clearly see.

As far as remediation, how far do I have to go? Am I going to have to sand the entire outdrive down to bare and re-prime and paint, or can I just hit the affected areas? I know that ideal would be to do a complete strip and refinish, but I don't know if that's in the budget for this year. On the other hand, replacing the drives next year isn't in the budget either. Just wondering if there's a happy medium available to me.

Thanks for all the input and advice!

 

[Lazy Daze]

As far as remediation, how far do I have to go? Am I going to have to sand the entire outdrive down to bare and re-prime and paint, or can I just hit the affected areas? I know that ideal would be to do a complete strip and refinish, but I don't know if that's in the budget for this year. On the other hand, replacing the drives next year isn't in the budget either. Just wondering if there's a happy medium available to me.

It depends on how "pretty" you want it to look. But simply for effectiveness, just do the affected areas. Still give the whole drive a quick scuff, but there's no need to "go to town" on good areas. It shouldn't be that big job, at all. Once you get started, it will probably take you less time than you think.

 

[redneck joe]

prime bare spots with [h=2]Zinc Chromate[/h]

 

[fwebster]

While it might be tempting to pass this off aas a fluke, any corrosion on the hub of the outdrive is cause for alarm. If the corrosions has continued for a while, it will eventually reach the bearing carrier behind the prop. There is a seal in the face of the bearing carrier and when the corrosion runs behind the seal, the lower unit leaks water into the gear case. If you don't know it, you usually only find out there is a problem when the lower unit grenades about 10 miles from your slip. Then, you only find out how bad (expensive) it is when the service manager calls you and tells you the lower gear case has to be replaced.

This is not a B-III outdrive....it is the only ready photo I could find........but the principle is the same, except there is usually more dissimilar metal corrosion on a B-III than a B-I or B-II. Save some time, heartache and $$ and repair the outdrive before you launch the boat in the spring, but even more important is figuring out what is causing the corrosion in your particular case.

 

[Madifonzo]

Jason- do you have a product listing for the red controllers with the transom pucks? I can't seem to find them. Also, do you know if they can operate in tandem with the blue controller I already have on my drives?

 

[jason78]

Jason- do you have a product listing for the red controllers with the transom pucks? I can't seem to find them. Also, do you know if they can operate in tandem with the blue controller I already have on my drives?

The part number is 42600A14. This is a kit that includes the two transom "pucks" and the RED Controller. As far as the controller, no, you will need to use the RED controller as the blue ones are not capable or supporting more than the anode mounted on the bottom of the gimbal housing.

http://www.marinepowerservice.com/BoatingStore/browse_detail3.cfm/productID/44820.cfm

 

[Madifonzo]

Sorry I should have been more specific. Can I use the red controller with transom pucks and still leave the gimbal units active using the blue controller...in essence running four separate units. Not sure if that's what's needed...one the boat is splashed I am going to have the system tested. I have read that you can have too much protection which can also lead to corrosion.

 

[jason78]

Sorry I should have been more specific. Can I use the red controller with transom pucks and still leave the gimbal units active using the blue controller...in essence running four separate units. Not sure if that's what's needed...one the boat is splashed I am going to have the system tested. I have read that you can have too much protection which can also lead to corrosion.

The RED Controller replaces the Blue one. There would really not be anywhere to mount a secondary unit aside from just ty-wrapping it down or something and you would have to splice extensions on to the power wires. I am not sure what you are trying to achieve by running dual units but the RED units have extra, separate terminals and are designed to run the stock Gimbal anode along with the puck set. If you have the pucks installed, you should be running just the RED controller to run all three anodes. Since that is the way it is designed to work I would not suggest installing it another way.

From product description-

42600A14
Kit includes new high output red controller and 2 transom mounted anodes for boats
requiring additional corrosion protection. This kit is used in conjunction with gimbal
mounted anode/reference electrode unit p/n 98869A14. The new red controller
replaces the existing blue controller mounted inside the boat.
Fits R, MR, Alpha One, Gen II & Bravo drives