Tank sensors

[Jammer]

Presently I have a hodgepodge of level sensors aboard for two water tanks, a waste tank, and a fuel tank. This includes a Tank Tender for two of the tanks, a cheap an inaccurate electric float gauge for diesel, and no sensor at all for the bow water tank (which is sort of translucent so you can sort of guess if you pull up enough cushions to get to it and use a flashlight).


Any advice? I see adding two channels to the Tank Tender as the cheapest alternative but that's pretty old technology.

[Dockhead]

Tank Tenders are fabulous -- bulletproof, last forever, totally simple, easy to install. Bit kludgy to use but worth it in my opinion. If I were building a new boat, that is what I would specify. If you have that system already I think it's a no brainer to add more channels. My father always had these on his boats and swore by them. Sometimes "old technology" is the best!

At the other end of the spectrum is what I have -- Maretron ultrasonic ones which connect to the N2K network. Easy to use, data available anywhere on the boat. But depends on the network being up, power available, etc. But the good thing about these is that they are extremely accurate and zero moving parts, don't clog, no mechanical failure like the standard float-type ones, which I would avoid.

[Orin]

Blue Seas 1839 display will cover 4 tanks with resistive sensors. Ultrasonic is good for the poop tank. And may work for your other thanks and can compensate for oddly shaped tanks and output alarms with programmable hysteresis which is better than what the equivalent BEP unit will do.

They’re worth looking into if you like resistive signal type sensors.

The tank tender system doesn’t have a way to linearize volume based on non-rectangular tank shapes.

There are much better solutions but I think the blue seas is a good bang for your buck if you’re looking at an off the shelf small scale solution.

[jamhass]

Another vote for TankTender. Maybe an old technology, but straight-on reliable and easy to use. Also, the company is really easy to work with. Give them a call and describe what you want. They will recommend the proper bits and give you detailed instructions.

[hjohnson]

I’ve gone all in on the Victron system myself. The resistive float on my diesel tank is connected to my Cerbo GX. I’ve also just picked up a GX Tank 140 USB device which can use standard industrial 4mA-20mA current loop sensors. The plan is to buy some cheap throw-in pressure sensors (about $40 each) so that I can measure my two potable water tanks, my blackwater tank, and my bilge sump.

The nice thing is that because there are no moving parts, it’s unlikely that the sewage sensor will get affected by poopsicles. I can also do some automation like actually monitor the performance and frequency of my bilge pump.

[Bycrick]

Tank Tender is a great product, as pointed out. But expensive. The equivalent parts, direct from Parker-Hannifan, are widely used for pneumatic controls and available for a fraction of the cost.

[JBP]

The Tank Tender has a lot of supporters as an excellent system, but oooh is it expensive, over $600 for one tank. The Tank Tender copycat, ultrasonic, and scad sensors are also in the $200 range. I've survived years with no gauge, so I don't want to drop $200 to $700 on a gauge. I realized my phone has a barometer, which is just a pressure gauge. 1 inch of water is 2.49 hPa. So I bought a $5 waterproof box and a tiny air pump for $7 and made my own. I hotglued a needle and cone (which came with the pump) to the box, and my phone goes in the box. I just built it today, so I've not tested on my boat, but testing in a jar of water it is accurate to about 1/2 inch. I intend to slide the tube down my pump out fitting. I'm not going to do the fresh water tank, certainly not with the same tubing

[CaptTom]

Originally Posted by Dockhead

...At the other end of the spectrum is what I have -- Maretron ultrasonic ones which connect to the N2K network...

My concern with ultrasonic is that the fuel/water/waste is always sloshing around underway. Do you find that they are only accurate when it's relatively calm? Or is there some sort of averaging logic? I've also heard of issues with the walls of the tank returning some signal when the level is low. That didn't happen with my home heating oil tank, but maybe I just got lucky.

Originally Posted by JBP

...So I bought a $5 waterproof box and a tiny air pump for $7 and made my own...

That's pretty clever! You could make a permanent install with an old, obsolete phone if it has the pressure sensor.

I imagine you can buy just a pressure sensor and connect it to, say, an ESP8266 to roll your own. There would still be the issue of displaying the data or making them available on the N2K network.

Honestly, the cost of these "marine" level sensors is obscene. The parts should be very inexpensive. I don't mind paying for the effort which went into integrating them, but I feel like the manufacturers are milking it.

[noelex 77]

Originally Posted by Jammer

Any advice? I see adding two channels to the Tank Tender as the cheapest alternative but that's pretty old technology.

I agree with Dockhead. The Tank Tender system is the most reliable, accurate and durable system. Unfortunately, normally it is the most expensive option. If in your case this is the cheapest alternative due to the existing installation, then the choice is easy

[AKA-None]

And to top it off you can’t find anything cheaper in the rv market either

[JBP]

Yep, the charpest I found is this system for RV's which is very similar to the Tank Tender for $165.

https://horstmiraclegauge.com/

[Jammer]

Thank you all for the advice. I will plan on expanding the tank tender setup.