Sacrificial Guppy question

[baz]

So I read another post where a discussion about how to properly connect a 'sacrificial Guppy' to the boat correctly. What I did not understand from that discussion was just how effective this technique was in slowing down the rate of zinc erosion.

My understanding was that it did but this simply raised a question in my mind.

If the Guppy does in fact slow down zinc erosion then why not hang two or maybe three or maybe four Guppies overboard ?

I know this zinc erosion is all about the affect of electrolysis where by current flowing from the boats's metal parts into the conductive liquid (i.e., water) and onto other metal parts (dissimilar metals) causes metal the current is flowing from to erode -- much like a battery. Have Zinc attached to the boats underwater metal parts helps solve this by having the zinc erode rather that the important parts of the boat's metal parts such as the prop or rudder. Zinc is used (and it must be bolted tightly to a good clean surface of the metal it's protecting to enhance the electrical connectivity) as it produces a higher voltage than most other metals commonly used on boats.

If the Guppy is electrically connected to the house battery -ive terminal just what boat metals is it protecting ?

 

[Andrew Custis]

All of the thru hulls, strainers, rudder and other equipment that is bonded through to the battery negative ground. Just follow the 8 gauge green wires you see in the compartments as those are all bonding wires. One guppy zinc is enough for your application.

 

[Captmike]

So does the grouper/guppy zink take the place of an isolator?

 

[captainmike]

Do not hang a school of zinc guppys of your boat it is possible to over zinc createing a problem .

If your zincs are not being eaten away at a rapid rate just use the factory number of zincs.

If the zincs are rapidly deteriorateing check your bonding system if you are at a marina ask the boats around you about their zincs.

The stray voltage in the water can be measured and try to determine if it is coming from your boat a neighbors boat or the marinas shore power.

A galvanic isolator stops low voltage coming through the marinas shore power ground but will not help a problem with your wireing or the faulty wireing on a nearby vessel

Capt. Mike

Ranger M21

60 passenger steel charter boat