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         Holding Tank
          
Monitor

   Photos

Holding Tank Monitor

The holding tank on Santosha is a rather small 11 gallons. It is Stainless Steel so installing a monitor is somewhat difficult. Although pricey the Gobius4 system seemed like a reasonable solution. The Gobius is manufactured by FM Marine and sold through AB Marine in the US. It mounts on the outside of the tank and uses vibration and accelerometers to determine the waste level. The system is pretty easy to install. I took power from the light over the sink. The directions were a little lacking so I needed to use an ohm meter to determine which wire was + and -. The wiring is not marine grade tinned copper so I coated the bare copper with dielectric grease prior to crimping lugs on. The manufacturer recommends using Vaseline on all connections so I figured dielectric grease would work fine and I used it on all connections. Note that even the control wiring to the panel has bare copper connections.

Calibration is simple but requires the tank to be empty. While it is turned on it runs every 5 min to determine the tank level but you can turn it off easily when not needed. Each time you turn it on it will run and give you the current level. It only shows empty, 1/4, 1/2 and 3/4 tank levels. The paperwork does say something about hooking an analog gage to an extra output. I haven’t explored that yet but it would be nice to have a more accurate reading.

I cut a slot in the fiberglass for the cable and mounted the control pad above the sink making sure it would clear the door over the sink.

I checked the readings by adding one gallon of water at a time. I did get one erroneous reading and will monitor that to see if it happens again. As it is the 1/4 level it is not too important. The readings are as follows for this 11 gal tank:

Empty - 0
1 gal  - 1/4
2 gal  -   0
3 gal  - 1/4
4 gal  - 1/4
5 gal  - 1/2
6 gal  - 1/2
7 gal  - 1/2
8 gal  - 3/4

I stopped at 3/4 as that is the max reading anyway. Reading seemed reasonable except for 1 gal. Note the Jabsco pump takes 24 pumps per gallon.

Some final thoughts. The directions recommend using a fuse in the power line but none was supplied. They also say you need to check the settings to make sure they are correct for your tank. I ordered it for a SS holding tank and the unit came set in the default mode “Gauge 0 - 180 ohm European Std”. The setting need to be changed if the tank is thicker than 2 mm and you are supposed to remove the adhesive pads from the sensors and use epoxy to install. No epoxy was supplied. I also don’t know how to tell the thickness of the tank but the brackets welded on the outside are about 2.5 mm. Epoxy seems rather permanent too and I would like the option  to remove/move the sensors if needed. The wiring and connectors are not marine grade. My overall impression of this system is that it is a little too new and not refined for real manufacturing yet. I reminds me of lab built equipment using off the shelf components. Still - it seems to work and no other solution seems feasible at the present.

Update: Less than 2 months later I needed to recalibrate as it read 1/4 when the tank was empty.

[S/V Santosha] [Nov 09] [May 10] [Aug 10] [The Boat] [Specifications] [Modifications] [Photos]