Tank liquid level senders

[Chuck Hawley]

I will second (or third!) the installation of WEMA sensors. When I redid Surprise's electrical system, I installed one of the Blue Seas electrical system monitors, and therefore had the ability to measure water and diesel. I gave WEMA the exact depths of the tanks, and they sent semi-custom sensors which worked perfectly with the Blue Seas software and hardware.

My only issue is that the tanks were placed under the P&S settee berths and were quite shallow and long, so they were not ideal, although they did make use of otherwise useless space.

Chuck

[sailcrazy]

I've had the WEMA Kus system installed for some 15 years. I've had to replace water, fuel and holding tank sensors, and gages. They work...sometimes, and other times...not so good. But the problem is I can't trust the reading. It never goes to tank empty, but a full tank will sometimes read full, or 3/4, or 7/8 or ??? And then a sender will just quit, with no visible signs of failure except the reading. It's a system, and it does show a reading...but my confidence in it's accuracy is gone-I'd have great difficulty in recommending WEMA to anyone.

[StoneCrab]

Originally Posted by Tayana42

Peg, any advice for monitors for a holding tank built in out of plywood and fiberglassed inside and out?

There are some tank level sensors that are basically the same capacitive senors that SCAD uses but the sensors are mounted inside of a PVC pipe which is then inserted into the tank. Since the pipe is sealed at both ends, the sensor is not in contact with the fluid. This would work with any tank of any construction as long as you can drill a hole in the top of the tank. The guy selling those pipes at the boat show">Annapolis Boat Show told me that you can cut the pipe to any length and then recap it. The length gets corrected for in the meter configuration. .

I'll look for the product brochure and post it if I find it. I thought

[Tayana42]

StoneCrab, thanks. I’ve just heard from Mr Appolonia at SCAD that they have just the one you are describing using the PVC insert. I’ll explore that further.

[wsmurdoch]

There is a photo of one in post #17 of this thread.
https://nebula.wsimg.com/b74b32bd602...&alloworigin=1

[StoneCrab]

I found my paperwork from Annapolis and remembered that they didn't have any brochures on this sensor, so it was good that wsmurdoch provided a link.

Given the number of metal and composite tanks in boats, this style of level sensor represents a very practical solution, yet finding it on-line is difficult. I think Mr Appolonia at SCAD is missing an opportunity by not creating a sexy brochure for this sensor since in theory, it should beat out all others. No moving parts, sealed electrical parts, infinitely variable installation length, simple installation... what is not to love?

That said, I haven't installed one yet. It would seem to have an easy life in fuel, I've been wondering how sensitive they are to buildup in other fluids. Then again, it is easy enough to pull the tube and wipe it off as part of a routine maintenance procedure.

At the show, if I hadn't asked them specifically about whether a solution exists for metal tanks, I would't have learned about the tube sensor. It was pulled out from under the table and not on display.

My fuel tank is shaped like a "T" with the vertical part going into the bilge. The tank keeps getting wider as it goes up. This presents a problem when determining the amount of remaining fuel since once you get into the narrow part of the tank, the level drops much more rapidly than in the first third of the tank. I was told that the tank shape can be accounted for in the SCAD unit during setup and calibration.

I am seriously considering this setup for my boat.

[ramblinrod]

Originally Posted by Tayana42

Peg, any advice for monitors for a holding tank built in out of plywood and fiberglassed inside and out?

These types of devices use a capacitance /admittance measurement between metallic strips to determine level.

They will work on any non-conducting material. If a plywood core is dry, no problem, if saturated wet, problem (in more ways than one).

[ranger58sb]

Originally Posted by Miket99

Is anyone familiar with Wema Kus liquid level senders? I have no way of telling when my black water tank is full--until it's too late. Also for fresh water tanks--no way of knowing when they are getting low except when it too late. What brands are you using?

Yes, we have WEMA/KUS senders for holding tank, freshwater, and fuel. The technology isn't rocket science, but they all work well enough.

These are usually installed with an inline fuse, resistance direction chosen according to the gauge you're hooking it to...

After some years in the holding tank, or if something untoward gets temporarily stuck in the float tube, the float can stick... so we actually have two senders for that tank.

First level fix is just to give the tank a big THWACK! with a mallet; that usually solves those temporary/one-off issues. Or if we begin having a real longer-term sticky problem, it's a quick out with the old, in with the new, clean the old, wait a few years 'til next time.

If you can't always see the tank, it helps to eyeball-calibrate the sender/gauge to full levels just after finishing the installation.

BTW, the original WEMA holding tank and freshwater senders that came with the boat, installed circa 2002, were plastic, and crap. Their current models are stainless, seem to work fine (after remembering to eyeball calibrate first).

-Chris

[sailcrazy]

Calibrate??? This is the first I've heard of any calibration needed for WEMAs. Please explain how to do that....maybe that's the issue with my water(4 ea) and fuel senders!

[ranger58sb]

Originally Posted by sailcrazy

Calibrate??? This is the first I've heard of any calibration needed for WEMAs. Please explain how to do that....maybe that's the issue with my water(4 ea) and fuel senders!

I just mean if the sender/gauge says full, visually (or otherwise) verify the tank is actually full.

Came up in our situation because the innie/vent fittings on our original tank were side-mounted... which in turn meant we lost the top 3-4 inches of capacity... which in turn meant the tank was full when the gauge said 2/3rds.

-Chris

[MickMeck]

Having similar frustrations about not knowing tank levels I installed iSeries Tank Monitors on my holding tanks as well as my three water tanks. I couldn't be happier. They work. They install easily. A great price performer.
https://tankedge.com/products.html

[frankv1205]

Maybe this will help

https://www.electrosense.com/fresh-water-monitors.html

[martin.purser]

I have 7 tanks on board (5 fuel) 1 black and 1 grey) All have wema/kus senders. They are connected to Summit G2982.1 digital 0-100% gauges (about $30 each all work perfectly). I have calculated the capacity at different levels, and matched it to the % full on Graphs kept on the bridge. With a holding tank you must use the correct type of sender (non clogging). You must also make sure you have the correct ohm ratings on the sender and the Guage.

[martin.purser]

Here's a picture of the gauges

[jrambo316]

Originally Posted by Dockhead

If the OP has an N2K network, he can use the Maretron ultrasonic tank level sensor with baffle: https://www.maretron.com/products/tlm100.php. This is bomb proof and wholly unaffected by fouling. You can display the data on a variety of different network devices, including most likely your main chart plotter, or you can buy one of the smaller DSM MFD's.


Another really bomb-proof solution for this, albeit expensive, is the Hart Tank Tender system: https://www.morganscloud.com/2005/11...-hart-systems/. In my opinion, this is a really superior way to monitor levels in all kinds of tanks. Totally simple, no electricity involved, almost nothing to break, immune to fouling. These are a little wonky in use because they don't read the tank level directly, they read pressure. So you have to make and post a little card showing what level is represented by what pressure, with regard to each tank. Still, I love these things

We have tank tender on all tanks. In our experience, it has been fine for water and diesel but not for the black water tank. We added a float switch that triggers a light when it is 90% full. I have a sixth sense now and can often predict the light. Also, we count engine hours to confirm the diesel reading. The calibration chart is not all that reliable.