Holding Tank Capacity

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Joined: Mon Apr 25, 2016 3:55 pm

Holding Tank Capacity

Post by AlanH »

I have always wondered exactly how much holding tank capacity is left based upon what the tank gauge is reading on our 2006. I realize it might not be the same setup on some of the boats but maybe this will be of use to some of you. I had the tank pumped out and started adding water two gallons at a time.

The float and sending unit in the tank does not go to the bottom of the tank. The tank is 31” deep and the Float is only 24” deep. The float manufacturer says not to have a float that goes more than 3/4 of the way to the bottom of the tank. As a result, the gauge does not move until the tank is almost a third of the way full. Tank capacity from empty to completely full is 41 gallons on our boat. Usable is probably 38. He are the gauge readings. I tried to get the pictures to load the correct way but the first three are sideways.

Just above Low took 10 Gallons 28 gallons left

IMG_6410 2.jpeg

Right on the High mark took 22 gallons 16 gallons left


Just touching the lined area in the “Full” quarter
of the gauge took 30 gallons 8 gallons left


Gauge just touching the Full mark took 38 gallons.
Recommend not pushing it beyond this point. 0 gallons left

Alan Hendry
2006 34' Hull #81
75hp engines
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