R31 Water Tank Gauge Sender

[OdyseaII]

Since we recieved our R31 CB back in March the water tank level has read full even when the tank was empty.

Following comments other comments on this board decided to try to remove and check the sender inside the tank. This required me to remove an access panel in the cave berth, which was not that big a job once I found all of the screws.

The problem was once I unscrewed the sender from the tank I could not remove it due to the limited amount of space above the tank. The sending unit is approximately 8 inches long and the gap from the top of the tank to the cabin floor is at most 3 1/2 inches.

I was at least able to confirm the sending unit sends a signal when the float moves but it does not move freely.

The only way I can see to remove the sender is to unmount the tank and slide it in to the cave berth space. The challenge is this will require I disconnect the fill and vent hoses.

Is there another way?

Thank you,
Keith

 

[H28]

I am not sure that I have ever had an accurate read from a water tank on any boat I have ever owned. Sorry, not very helpful comment, but there you have it........

 

[FlyMeAway]

I've never had a resistive float sensor that works.

I've had some luck with capacitive sensors and ultrasonic sensors. The former require a lot of fiddling and calibration when you first install them, but seem to work well after that (I had one on my sailboat); the ultrasonic ones are even more painful to install but IME helping install on a friend's boat they are very very accurate (commercial vessels that don't use flow meters tend to use ultrasonic sensors; I've heard but haven't confirmed that ultrasonic is typically used in naval vessels as well).

Here's the capacitive one I installed on my sailboat. Should be a pretty easy retrofit on our tugs, and definitely something I've considered.

https://www.defender.com/product3.jsp?n ... id=1345546

 

[JeffreyAC77]

The only time our water gauge works is on fill up - showing full. It then operates to about 1/2 full and stays there so we always fill up when we get to 1/2. I have discussed this very issue with other owners who have experienced similar issues.
We have a 2015 R31-CB.

 

[OdyseaII]

Thank you for the ideas. The capacitive sensor is very interesting however I really do not want to have to replace the gauge. It would be great if I could use the float sender gauge with the capacitive sender but it does not look like this is the case.

Thank you,
Keith

 

[Ralf H]

Hi Keith,

Yes, unfortunately getting to the sender is a bit tough, but if you can get the tank loose, you should be able to move it aside enough to get the sender out. I think you might have enough slack in the lines to get it to move enough for the sender to be accessible. Hopefully this helps a bit, but let us know.

Cheers,

Ralf

 

[Wee Venture]

We have a 31CB and the water tank gauge works reasonably well. (It’s off but still consistent enough to give us an idea). However I fully expect that it will start malfunctioning at some point; they have a limited lifespan.

When it does, I plan to replace it with this SCAD unit:
https://www.defender.com/product3.jsp?p ... id=6539568

I’m not sure what your hesitation is about replacing the readout gauge, but the new one should fit in the same space as the existing gauge, and be a lot more reliable. The entire job should be much easier than replacing the sending unit with the same (very old) rheostat technology. I installed an earlier model SCAD unit on a boat we used to own and it worked well. Just my two cents.

John

 

[OdyseaII]

Thank you for all of the answers and feedback.

Plan plan is to give the current gauge technology one more try and if that does not work I will revert to the outside tank technology.

In the end it is not a huge inconvenience to lift the hatch and glance at the level before we are heading out on a cruise.

Thank you,
Keith