Water tank gauge?

[MM5AHO]

I have a stainless water tank located on top of the keel and under the sole in the main cabin. The top is visible if the floorboards are lifted. There are two outlets that go through a bulkhead into the main bilge area where hoses take water to the 2 pumps for distribution. Tank is an odd shape, built for the hole it occupies. It's about 200 litre capacity.
I'd like to know what the contents are at times, but there's no way to tell. There's only 4 holes, the two outlets, the 2" inlet hose from a deck fitting, and a tiny breather tube. No inspection hatch.

What options can you suggest for fitting a contents gauge at reasonable cost this coming winter?

 

[knuterikt]

Cut a hole using a hole saw. Some options.
1) add a lid and use a dipstick
2) install a tank sensor.

for option 2 I would use adapter for 1.25” BSP
like this https://osukl.com/mounting-ring/
there is different sensor to choose from.
We have installed this one https://osukl.com/water-level-senders/

 

[JumbleDuck]

We have installed this one https://osukl.com/water-level-senders/

For true sophistication, the sensor could be linked to some signal-processing electronics to produced a linear read-out. Calibrate by filling from empty 10 litres at a time. Could be a job for a Raspberry Pi, but I'd use an even simpler BBC micro:bit for this one ...

 

[johnalison]

I have a standard gauge with a needle read-out which has worked well for nearly 20yrs. I should know the name of the sensor, having fitted a new one a couple of years ago but have forgotten, but it has a floaty thing. The read-out is fairly linear and I don't need any fancy electronics. I know that when it gets down to the red sector there is still a reasonable amount left but I need to fill up before taking a shower.

 

[Norman_E]

This type of tungsten carbide hole saw will make the required hole in a stainless tank. https://www.ebay.co.uk/itm/6Pcs-Set...TR1.TRC0.A0.H1.XTungsten+carbide+holesaw.TRS0 I have two grey water tanks made of 2mm thick stainless steel and cut 32mm holes for gauge senders with this type and a small battery drill on low speed. The best technique is to rock the drill slightly so that only one tooth is cutting at any time. When the saw is through at one side of the hole, stop drilling, put a screwdriver through the centre hole and bend the waste material to brek it out so that it does not fall into the tank.

 

[prv]

Do the outlets come out of the bottom of the tank? If so, there are senders which can be tee-d into the pipe and read the contents based on the head of pressure.

Maretron tank sensors can be calibrated either based on a table of calculated depths or by filling bit by bit and telling it how much you just added. Probably works out a bit expensive for a single standalone gauge though; they're usually used as part of a relatively sophisticated boat monitoring and control system.

Pete

 

[john_morris_uk]

We have one of these: http://www.thetanktender.com

it reads the depth of water or diesel (or black waste) in each tank (according to which button you press). Simple and reliable and only a small hole in the top of the tank to screw the fitting and tube into.

 

[jordanbasset]

I got some good advice on this thread, lots of other options besides the one I went for
http://www.ybw.com/forums/showthread.php?502663-Fresh-water-gauge

 

[knuterikt]

For true sophistication, the sensor could be linked to some signal-processing electronics to produced a linear read-out. Calibrate by filling from empty 10 litres at a time. Could be a job for a Raspberry Pi, but I'd use an even simpler BBC micro:bit for this one ...

I got it calibrated from Oceanic Systems, just filled in the calibration form pre order. It outputNMEA 2000 PGN 127505 parameters (instance number, type of fluid, level of fluid, and tank capacity.