Anode on hull in salt water?

[ggoldy]

I'm rigging a new Tracker 1436 jon boat. As long as my back holds up, it will be 'rowed' on Florida's gulf coast intercoastal waterway, salt water. No motor, and it won't be left in the water. Would it be helpfull to put an anode on the hull? I'm a retired plumber, this is the last boat I want to buy, and I want it to last me 20-30 years.(I'm very frugal, and, well, cheap!) Thanks for your help.

 

[kfa4303]

Hi g. If the boat is going to be stored, or sit in saltwater for long periods of time you'll definitely want a sacrificial Zinc anode attached to the hull below the waterline. Make sure that any hardware on the boat is either aluminum and/or stainless steel, or it will rust away pretty quickly.

 

[Zum]

Here's a good read,easy to understand and not to long.
https://www.duroboat.com/experience/AluminumBoatsandCorrossion.htm

 

[PSG-1]

I keep aluminum boats in salt water year round, and because of that, I am a firm believer in anodes. I have seen enough electrolysis damage on boats without galvanic protection. If you have a battery in your boat, connect a bonding wire from the negative post, to your zinc anode. This will help direct any stray current into the anode, instead of your hull.

 

[PSG-1]

Zum » Today, 14:44[/url]"]Here's a good read,easy to understand and not to long.
https://www.duroboat.com/experience/AluminumBoatsandCorrossion.htm

Very good info for those who keep boats in saltwater.

However, there's one part I disagree with:



"Isolate the hull from electrical current. Make sure your battery is grounded to your motor. Don't ground electrical devices to the aluminum hull."



Well, the fact is, if you have an outboard engine that uses electric start, you have an electrical device grounded to the hull, since the negative battery cable is grounded to the engine block, which is in turn grounded to the mount brackets. So, although your electrical system may have seperate ground wires run for each device, which keeps those devices from being grounded to the hull, as soon as you install the motor, it's grounded. And this is why you need to make sure to carry a bonding wire to the hull anode. Outboards will generally have a bonding wire, and if it's a power trim model, the wire will continue on to the anode mounted under the PT unit (at least, on Mercurys)

 

[Syncrowave]

PSG-1 » 13 Aug 2013, 15:40[/url]"]If you have a battery in your boat, connect a bonding wire from the negative post, to your zinc anode. This will help direct any stray current into the anode, instead of your hull.

I've been boating in saltwater most of my life and I have never heard of this. I've heard of bonding everything metal that goes through the hull together, so that you don't need to attach a zinc anode to every seacock and through-hull fitting, but never that it should be connected to the negative post on the battery. Seems to me that unless the (+) terminal is somehow in the circuit, it's not going to make any difference.

At any rate, unless you keep your boat in marina near boats that are using shore power, stray current isn't much of an issue. There will be current because of the dissimilar metals submerged in the electrolyte (seawater) but that's just the nature of a galvanic cell.

 

[PSG-1]

As I mentioned about outboards with electric start, all bonding wires go to the engine block, which is in turn connected to the negative terminal of the battery. And you're correct about having everything bonded together, this eliminates the need to put an anode on every piece of metal below the water.

Stray current is indeed a problem in marinas, but there can also be areas far away from shore power that seem to be 'hotter' than other areas, due to many factors, such as pH, salinity, certain types of sediment or algae, etc. Or even from stray metal in the water left over from old pilings, etc.