Only on a friend's Northern Bay 36 .
He likes it a lot , but it does not appeal to me very much.
It is very accurate it terms of indicating depth , since you manually pump a little soft bulb on the panel until the additional pumped air escapes from the down tube in the tank.
That shows the maximum pressure ( over ambient) needed to overcome liquid column pressure and relates consistently to depth no matter how irregularly-shaped the tank may be.
You need to set up a log of fills at various depths so you gradually have a very accurate conversion reference sheet : displayed pressure vs gallons(or liters) of liquid to refill the tank at that pressure. ( Liquid Used).
If desired , you can subtract that gallons(L) figure from tank full capacity to add Fuel(or other liquid)-Remaining data to the reference sheet. With appropriate model Tank Tender you can just pump air into whichever tank you want to check so you only need the 1 Tank Tender dash panel.
It does require an air hosefrom the dash panel to each tank as desired and hose connections must be tight enough to seal the very low pressure involved when checking.
Of course, for those tanks with existing and working gauge senders, one can do the same thing diagramming in your log book the gauge and (E,1/4, 1/2,3/4, F) register marks ( and helpfully add a few more in between with a marker on the lens or bezel) and show the gallons it took to fill at each needle position or digital level % number.
Then your dash gauge eventually becomes very accurate ( ~~ =/- 1gal) as well.
