the readings should be:
More positive than (-0.70) = no protection
Between (-0.70) & (-0.80) = Inadequate protection
Between (-0.80) & (-0.95) = ADEQUATELY PROTECTED
Between (-0.95) 7 (-1.05) = Adequately protected, High Range
More Negative than (-1.05) = Over Protected
These readings are for generally checking for poor connections on your bonding system but in your case should show your binnacle up as more positive than -0.70 moving towards -0.60 and beyond.
On the Ma scale with the meter in series with the zink the readings will be in the 10 to 50 Ma. range. They recommend testing be done on volts. I hope this helps.