ICCP Bonding Tutorial

Naiad Roll Stabilizer Shaft Seal

Ah yes!...the airport's fogged in, usually on a Saturday morning, pilots are hanging around the hanger (do you suppose that's how it got the name?) and engaging in lots of hanger talk, their hands zooming around to demonstrate this and that. Many are bankers, store clerks, used care salesmen and the like. They'll get into deep discussions about aeronautical engineering, electrical engineering, transmitter engineering...and lots of other stuff, such as "the Japanese stole the idea for the helical scan videotape recorder from the Americans. Well actually a guy by the name of Takaianagi got it going, back in the early 60's at Japan Victor (JVC).

Like the pilots, mariners go out on the same long limbs with similar wild tales. Go to just about any marina on a Saturday, with your cup of coffee in hand, press yourself into a dockside discussion about corrosion or bonding, and things will get downright lively in short order. They love their little ships and many, to avoid the $50 an hour (or more) technician, just "do it themselves". They can, they should. People learn, gain experience, and that includes dabbling in corrosion protection, which involves poking around in the rather theoretically "fixed" world of basic electricity. But regardless of opinions, new theories and ideas, a discussion of correct bonding does not begin with dissimilar metals and how someone has connected the ground on their radar and depth sounder. Bonding begins with a firm agreement of the two most basic electro-physical facts that no one has the liberty to toy with or change

(...including those times when it's returning back through ground)

...above the water, around and through your electrical system. Positive to negative below the water, around and through the various dissimilar metals that create highly active electrolytic cells.

The Other Naiad Stabilizer Seal That Did'nt Survive

(The atoms, electrons and molecules are out in the Pacific Ocean somewhere.)

Mariners usually arrive at the bonding process because they are trying to protect expensive shafts, propellers and rudders that are underwater, quite often saltwater. To understand the importance of bonding everything together, and the electrical purpose it serves, it's necessary accept the fact that there are two distinctly different and highly complex electric paths that reside on your vessel. One is the wired network connecting the battery, engine, and the multitude of electric and electronic accessories together. The other is an equally complex interconnected network of combinations of dissimilar metals. Some are alloys, like the bronze propeller, with its brass and iron that have been cast into what visually seems to be a single component, but in fact is a corrodable device. Other combinations are welded, and bolted assemblies where two dissimilar metals, albeit only slightly dissimilar, have been connected together, and form an electrolytic corrosion cell.

The reason for bonding is to connect everything firmly, electrically, together to create one single polarized negative component. Electric equipment and metals are provided with a good, low resistance, ground return path back to the "central" starting point, which is the battery ground connection.

The graphic shows a typical model of dissimilar metals that form the makeup of most boat installations. A stainless steel rudder underwater, the post extending upward through a bronze stuffing box, and a bronze tiller arm at the top.

A bronze propeller is an alloy, a mix of brass, and iron for brute strength, with possibly some silica and other exotic elements to make casting a little easier.The propeller is attached to a monel drive shaft, passing through a bronze stuffing box, and extending to the transmission and engine where it becomes connected to aluminum, iron or steel.

We can begin looking at corrosion with the dissimilar metals submerged in saltwater. For the river and lake folks, that'll be submerged in freshwater. Just a little less conductive.

Contact Us

Back to The ICCP Home Page