Do more zincs last longer?

Oct 26, 2010
1,883
Hunter 40.5 Beaufort, SC
I bought one of the Reference Electrodes and followed their instructions for measuring the Hull Potential and then the individual component potentials. Here are my results (RE is the Reference Electrode)

Readings with all DC loads off:
Bonded Connections as follow:
RE to Engine Ground -861mv (spec is -550mv to -1100mv per the RE manual for a fiberglass boat)
RE to Shaft -880mv
RE to Strut -864mv
Unbonded thru hulls - seems there is disagreement on which is best, bonded or unbonded?
RE to Generator thru hull -242mv
RE to Air Con thru hull - 266mv
RE to Yanmar thru hull - 220mv
Are the unbonded numbers acceptable? - the manual does not address this. Maybe I need to bond the thru hulls?

I then remeasured the Hull potential and started energinzing DC loads from the DC panel
RE to Engine Ground -870mv (all breakers off)
Spec in the manual says that potential should not change by more than 10mv
With each DC load on the max hull potential was -880 so just within spec.

Does this seem
 
Feb 14, 2014
7,400
Hunter 430 Waveland, MS
Look for links about silver/silver chloride reference electrode - a cheap investment compared with the cost of a new prop.
:plus::plus:
And above all "Peace of Mind"!!

Are the unbonded numbers acceptable?
Read this chart completely note the BLUE area.

GalvanicSeries.png

Then you make the call.;)

Bonding is a different subject and depends on how your boat is wired. Mine is wire per ABYC standards.
And not bonded as the chart above and AgCl probe suggests.
Jim...