Marinette Boat Forum

Got my shafts isolated! Getting my rudder anodes on this weekend. I did not check the reading after isolating the shafts. I will do that today.

FYI
Anodes about 4 years old. Tennessee River fresh water. Capac always reads about .90. Bought magnesium guppy (throw over the side with ground clip), Capac reading went to 1.15, which is top of the scale for our boats

Reading is now .81. I am getting tired of this. I disconnected all the batteries and my marina is currently without power. I also have no connection to shore power at all. No change in readings. CAPAC and reference electrode are identical readings. The only difference is that the water is up and muddy from all the rain. Would faster current cause issues? I love aluminum boats but this irritates me.

Ok... In fresh water this time of year... .81 reading is fine. Relax and have a cold one!

Also you can check your CAPAC calibration. Most are off. It is very simple:

1. Disconnect wires from Unit.
2. Use a digital meter.
3. Hook up meter (remember you are reading negative volts not positive.

4. Compare your meter reading to the one you had on the CAPAC.

You might be surprised your readings are higher on the digital meter.
There is a small plastic screw on front of CAPAC. Turn it clockwise slightly to raise the needle to match your digital meter.

The new digital meters are MUCH MUCH more accurate than the CAPAC meter.

safe boating,

dave

Here is another EASY tip to verify if your shafts are properly Isolated. (There is a tag on many Marinettes with the instructions )

1. Take jumper wire with alligator clips on both ends

2. clip on shaft coupler

3. Have helper push the Ole CAPAC button

4. Touch or clip on transmission or engine

5. If needle deflects downward (lower reading) you know your shaft is isolated.

That's all there is to it folks:)

safe boating,

dave

Just curious, why would that reading be acceptable now?

I just returned from a month of travel and my CAPAC IS READING 0.1 (for the past year, it always read 1.15)

I got 2 new neighbors, both running shore power. The nodes I can see / feel don't seem much more rotted than last time I checked em.

Should I be worried about my new neighbors or maybe a failed Galvanic Isolator?

Please read.
Electric Shock Drowning (ESD) Explained - Seaworthy Magazine ...
Stay out of the water.
Have your neighbors unplug their shore power along with yours then check the meter.
bill

If I am not mistaken it's not just your neighbor' set up that needs to be checked, it's anyone on the same circuit. Here's another simple way to test. Take the boat away from the dock and see whether the reading changes. Also, a clean hull often changes the reading (a little).

Most of the galvanic problems are due to DC problems, not AC current. A tiny bit of stray DC will dissolve aluminum lickety split

For those that keep their boats in fresh water year around... I highly recommend the use external mag. anode. The keel and rudder anodes do become fouled with growth and loose effectiveness and no many of use dive under the boat to clean them with a S.S. brush. The external mag. anode is easy to keep clean and does an excellent job of maintaining proper protection levels. It also is lower on the Noble scale and reduces wear on your installed anodes.

safe boating,
dave