bonding of underwater fittiings and thru-hulls?

[bob]

the underwater fittings and thru-hulls on my 40.5 aren't bonded together to an underwater zinc...i assume that hunter doesn't do this on any model....many but not all high end boats have a bonding system to guard against corrosion of the thru-hulls,etc...anyone out there ever looked into this?...anyone have an opinion on whether installation of a bonding system would be advisable?...i'm trying to get a feel for whether the substantial cost would be worth it....thanks

 

[Dick McKee]

Our 95 430 isn't bonded either,

and on our last haul out in May all the fittings looked like new. I wonder if they look that good in 5 years is the cost worth it. I'll be curious to see what other opinions and experiences are.Dick McKeeS/V Constellation

 

[Ernie Rodriguez]

Bonding thru hulls..

My opinion is that bonding of the thru hull fittings is a sure way to promote galvanic corrosion. Leaving the thru hull fittings "isolated" (that is, not bonding them) minimizes the potential for corrosion. For galvanic corrosion to take place you need two dissimilar metals in contact with each other and in a solution such as salt water. Bonding of the fittings involves electrically connecting all the fittings to each other with an electrical conductor and also to the boat system ground. Any other dissimilar metal also in contact with the water and the system ground ( such as the engine..iron) sets up a potential voltage (just like a battery)and the water provides a path for current to flow..... hence galvanic corrosion. My 1982 Hunter 36 does not have any thru hull fittings bonded, and they will stay unbonded. If they were bonded, I probably would need to use zincs to prevent them from corrosion.After 18 years, they still look like new.