Need to zinc outboard support

[hartflat]

Hi again,

My has been in a slip off the central California cost for about 3 months now. No bottom paint (yet) but have been paying for monthly bottom cleaning service to keep it from growing a beard. (It's a mystery... I leave it parked out there for a few days & out of nowhere, nasty stuff just starts growing on it.)

Here's the issue: according to the diver, I have some electrolysis around the outboard support & he suggested that I "need to zinc the boat some". The zinc slug on the Etec 50 appears to have plenty left on it before needing to be replaced, but I have noticed some residue accumulation on the support.

So, is this a non-issue, or is there something I'm neglecting here? Does the support need to be zinc'd independent of the outboard? And if so... how do you "zinc a boat" with a fiberglas hull?

Any thoughts?

Ray

[u12fly]

Perhaps he was suggesting a bottom paint with zinc?

ePaint ZO is a general purpose antifouling paint recommended for all rereational boats. ZO features the environmentally approved active ingredient Zinc Omadine® to prevent grass, slime, algae, and bacteria and ePaint’s patented photoactive technology to deter the settling and attachment of hard shell-type organisms.

[Crikey]

Ray, if it's not coating the hull that he's talking about then I would look into exchanging all the 'sacrificial' zinc anodes on the outboard. As well as the bar you mentioned there are various other locations that different manufacturers use. Another primary one is the torque fin behind the prop. Some zincs can be of low quality/purity, and others can be covered in oxide from too long outside storage to be 100 % effective. Wire brushing can help that out.
There are supplemental add-ons you could include as extra protection. I have zinc bolt caps on the outboard mounting bolt studs at the stern though my outboard is only 1 1/2 half years old at this point. It's fairly cheap insurance.

Ross

[hartflat]

Maybe checking the owner's manual every now & then would help.. Duh!



Thanks for the input guys. I'll be checking the mount anode next time I'm at the slip.

[Ixneigh]

Those zincs on the etec arent enough. The bottom end of the power tilt trim unit on mine was corroding after three months. The paint on the bracket was coming off.

I placed extra button zincs by tapping into the bottom of the trim unit and bolting the zincs on with a machine screw.
I also dangle a big hunk of zinc off the transom. I also only paint the transom with outboard paint.
My guess is that there is some stray current around the power trim tilt.. Bad wiring perhaps.

[hartflat]

Thanks for the tip Ixneigh,

You're probably right about the Etec not having enough zinc anodes to cover the bracket. Your idea of tap & screwing on one or more on the bracket sounds like a good idea & is something I'll try out when I take the boat out for the winter.

BTW, how did you dangle a hunk of zinc off the transom & what metal part did you dangle it from?

Ray

[hmb-barry]

My 2005 M with an ETEC 50 also had noticeable and significant electrolysis on the motor mount assembly because the OEM zinc was not long enough to be submerged in the water. I attached two zincs – one along the outside of the motor mount (using the threaded holes that held the OEM zinc) and one along the bottom of the mount. I also added a heavier grounding wire between the motor and the mount – the OEM wire was too thin and breaks easily. On the bottom zinc, I had to fabricate a small stainless steel tab for one side and then attached the zinc using some hard-to-find stainless steel couplings that threaded nicely on to the two small threaded studs that are on my mount. Sorry, no photos at this time – maybe in a week or two?

[K9Kampers]

BTW, how did you dangle a hunk of zinc off the transom & what metal part did you dangle it from?

Attach to transom bracket bolt...

[Catigale]

Strict limit of three sinks per season....

[Ixneigh]

I attached a

Short

cable to one of the motor mount bolts and attached a large zinc onto that. I did not use the fish because if you forget to reel it in it will get caught in the prop. Mine cannot get into the prop even if I forget to bring it in. It sits in the outboard well while sailing.
I suppose you could shorten the cable on the fish.
Also. Use zincs made for outboards. Zincs made for bronze and stainless I believe are less protection...somebody? Anybody? It appears that the hunk of zinc, bought at a yardsale, and the zinc buttons, made for lower units and bought at west, corrode at different rates. Are there differing grades of zincs?

Ixneigh

[Catigale]

I think, marketing hype aside, marine anodes are essentially pure zinc with trace amounts of Al and Cd from manufacturing. The protection and corrosion rates are galvanic and shouldn't vary much for a given shape.

[Hamin' X]

The following is from Volvo-Penta:

Which anodes should I use on my drive ( when using the boat in different waters)?

Anodes are installed from the factory on all Volvo Penta drives and transom shield. If you bought a second hand boat you have to inspect the anodes! Anodes are manufactured for different environments and will react to those. There are some general recommendations when choosing anodes. See chart below.

Anodes will if used in fresh water become covered with white crust of oxide (Aluminium ) or become yellow (Zink) which will stop the anode from working when returned to salt water. Zinc anodes react the same way in brackish water while the Aluminium anodes will work effectively in rivers estuaries and other brackish conditions.

Magnesium anodes are not designed for use in salt water so if you are taking your boat into salt water for more then 7 days you should consider changing the anodes. The same can also be applied for zinc and aluminium anodes if moving your boat between different waters.

It is important to inspect the anodes after shifting waters and if necessary also clean the anodes. The anodes can also be pacified just by being away from water. If the drive has been tilted or for example placed on a trailer for some time make sure to take a look on the anodes.

If an anode for example looks yellow or is covered in white crust it has been pacified and needs to be brushed or changed to provide protection. This can be done by brushing the anodes using sandpaper or an emery cloth. Note, never use a wire brush with steel bristles. You have to use an emery cloth without iron oxide otherwise the anode might be pacified.

Make sure to inspect the anodes on a regular basis and change them if more then 1/3 has been eaten away by corrosion. All anodes do not share the same quality! Always use anodes produced by Volvo Penta since they have been tested to ensure maximum protection on stern drives and props.

Anode---------------Material------------------Water condition

Transom shield------Zinc-----------------------Salt water
Sterndrive------------Zinc----------------------Salt water
Transom shield----Aluminum---------------Brackish water
Sterndrive---------Aluminum---------------Brackish water
Transom shield---Magnesium---------------Fresh water
Sterndrive--------Magnesium---------------Fresh water

[bscott]

Thanks--great info--a good learning day for me

Bob

[Crikey]

I would venture that an anode made out of Magnesium would be the most active as well as the quickest to deplete, and offer a higher protection base at the expense of more frequent replacement. Simply a pain to bother about more than once in the season. Lithium would be the ultimate!

[arknoah]

Thanks--great info--a good learning day for me

Bob

Exactly. I never thought about zincs, etc. for an outboard before.