Bravo III Corrosion

[Adam-swf]

Sorry for all the posts! This new to me boat was somewhat neglected. Anyway I noticed some corrosion on the lower unit, wondering how serious it is. I also saw a merthacode fuse in the battery switch compartment but don't know if it's functional or where it is installed. The boat is dry/lift kept and I keep the shore power plugged in, but I lower it into the water pretty often to work on it (maybe I'll complete the to-fix list someday) and then raise it out when I'm done.

-Adam

 

[Lazy Daze]

From that picture, I'm seeing more paint removal from running in low water and the skeg dragging through the mud/sand. The edges, that I can see look alright. If you have other pictures, it would be good to see the area directly in front of the props and without the props on, too.

It's always a good idea to clean things up, primer and paint.

The Mercathode is mounting on the underside of the transom plate (behind your hydraulic lines in the picture). However, it "looks" to be a standard, anode instead of the electronic unit. A working Mercathode does a better job than a standard anode.

It looks like you're missing the hydraulic ram anodes. Check the one above the prop and on the forward edge of the drive. You'll want to use either Al or Zn anodes (assuming you're in salt water). Check with locals as to which works best for your setup in your waters.

 

[Adam-swf]

Thanks again, I do appreciate it. I think you are correct, that is the standard anode and not the mercathode although I wonder what the fuse is for, will have to trace that. It also appears as though the ram anodes are missing now that I looked up what they look like. The PO did appear to run through some sand, we have plenty of shallow water here.

 

[Lazy Daze]

I think you are correct, that is the standard anode and not the mercathode although I wonder what the fuse is for, will have to trace that.

Your welcome!

The Mercathode unit was/is a standard item on the Bravo gearcases. So, my "guess" would be that it malfunctioned at some point and the PO didn't want to replace it and just popped a normal anode on there.

 

[GnrlPatton]

You should check that you have all the anodes on there, it definitely looks like you are missing the anodes on the rams, but there is also a prop nut anode, cavitation plate (x2 if I recall) and then one at the front of the drive on top of the cav plate. If you look for the Bravo III anode kit from Boat Zincs, you get all of the anodes and mounting bolts, as well as a diagram showing their position. They were all pretty easy to change out, the ram ones were a bit challenging though, until I realized I could pop the pin out and provide access to the blots.

It looks like you don't have anodes on the trim tabs as well, I would add a set on each. Basically anything metal that is underwater should get one. I even had some on my swim platform struts.

My previous boat had some pretty severe corrosion on the outdrive when I bought her. It was pretty straight forward to get all of that off and then repaint with Mercruiser approved paint - primer and anti-corrosion paint. It was a pretty simple weekend job, made easier since I had it on the trailer and could work on it in my driveway.

 

[Adam-swf]

Thanks for that. Definitely wishing I had a trailer for this sort of thing, I don't think a kayak will work. Probably have to wait until the next time I haul out for service.

 

[BillK2632]

I see you have a 1998 270? The BIII drive of that era did not have a prop anode and only one below the cavitation plate - the additional anodes were added 2003 I believe. You are definitely missing the trim ram anodes, but actually your drive looks pretty good except for the skeg. If it stays on a lift, you really are not going to have much of a corrosion problem, but you still should make sure you have all your anodes and the mercathode is working. The corrosion usually starts around the propshaft and any edges of the casing where the paint becomes compromised - I really don't see that in the picture other than the skeg. I do see some corrosion on the skeg, and what that is probably from is leaving it partially in the water, if just the skeg and prop are in the water, but none of your anodes are also in the water, your aluminum skeg is sitting right next to that SS prop and there is no anode there to protect it. I can't tell exactly from the picture, but the skeg looks pitted and corroded, but not too far gone to clean it up. I see this a lot around our lake where boats sit on a lift with the drive partially in the water. You should still keep the anodes in good order for the couple of days you might be in the water here and there. When it comes to outdrives, you have to keep them painted, once the paint is compromised, the corrosion sets in, you will start seeing areas where the paint looks bubbled.

 

[Ozshadow]

You can add a prop anode from boatzincs.com

Corrosion is likely hidden behind the inside prop though. The bearing carrier in those years was a vulnerable item. I am having a new one installed on my '99 freshwater boat.