I just installed two new through hulls/seacocks to replace two that were substandard. The old ones were not bonded and I have not yet bonded the new ones. I am undecided whether to tie the new ones into the bonding system. Should I?
*If you did not see any galvanic corrosion on the ones you removed, it is unlikely you will need to bond the new ones.* On the boats I have owned, I have always had one or two un-bonded thru-hulls for various reasons, and with one exception, they remained un-bonded because there was no apparent corrosion occuring.
The one exception was a generator sea water supply thru-hull which had obvious corrosion, and bonding it solved the problem.
The*bonding of thru-hull fittings and strainers can be a rather mysterious process, and many boaters/builders seem to think that it is better to bond all immersed fittings than not.* But one of the boats I owned (for 24 years) was equipped with an Electroguard cathodic protection system, and it*actually worked better when two of the forward thru-hulls were disconnected from the bonding system.* This was a wood boat that was sensitive to over zincing.
A big part of the solution on bonding/corrosion issues*requires*regular inspection*of the fitting and bonding system connections.* In addition, it should be recognized that*many bonding system/zinc protection issues are boat/area/usage specific, and it may take a number of years to understand how your system is working.**