S/Steel Thru Hull Bonding

CaptSteve53 said:

Just for clarification here's the definition of Galvanic corrosion from the dictionary(Yes cut and pasted): Quote :Galvanic corrosion (also called bimetallic corrosion) is an electro-chemical process in which one metal corrodes preferentially when it is in electrical contact with another, in the presence of an electrolyte. End Quote

Just saying !

Cheers Steve

Click to expand...

No quarrel with the definition of "galvanic corrosion" however there are often more that one "metal" or metal contaminants within what would otherwise be a single metal. In fact most metals are made up of more than one base metal. These contaminants (other metals) can set up a galvanic cell within that single piece of metal as demonstrated by the Groco and many other instances of metals from that "other" country.

The well know "dezincification" of brass is due to this process i.e. a galvanic cell caused by different metallic componentsl within a single piece of metal.

PS. Recently retired Certified Corrosion Analyst.

The skin fittings for the raw water intakes have been removed. Despite no bonding they show no sign of corrosion. So, perhaps the installing(former) shipwright got that right.
However, the fittings were easily, too easily, removed. Said shipwright used silicone, not Sikaflex, to install them.
Current shipwright proposes to dispense with backing plates due to the thickness of the hull, and to use Sikaflex. IGs have thick solid hulls, between 3/4-1". This is necessary to accommodate the osmosis which might otherwise penetrate the hull.

Thruhulls are always easy to remove , on inspected boats they are pulled for inspection.

The challenge is the seacock where thru bolting thru the hull is the tried and true method.

Some folks want to glue a plate to the hull and simply bolt to it.

Works if it can take 500lbs of load, but is nowhere near as safe as 3/8 or better bronze bolts.