Reply
 
Thread Tools Search this Thread Display Modes
 
Old 11-29-2020, 11:14 PM   #1
Member
 
City: Vancouver BC
Join Date: Nov 2020
Posts: 6
Diesel tank sender

Hi All,

My wife and I just got a Camano 31 Troll. Old but is in good shape.
Unfortunately, I am having issues with the fuel gauges. The tanks are 18 W x 44L x 14"H (external values). This equates to 48 USgal.
measuring with a wooden dowel rod I can measure the levels on both tanks. But the math (volumes based on stick readings) doesn't match with the gauges readings.
The port reading is stable but the starboard oscillates - sometime too much. One tech had mentioned the send might be bad and to replace is very crazy expensive - no access.
Noticed too that with engine running the levels on gauge are a bit higher.

Ex: stick reading 6.25" that would define a volume of 4950 in3 which is 0.446 ration of the full tank. But the gauge shows 1/4" ... maybe a bit above. Well 0.446 is almost 50% ... half tank!

Help here:
Options on fuel sender and metering?
How non accurate can the stick reading be?

Thank you all
__________________
Advertisement

Catam is offline   Reply With Quote
Old 11-30-2020, 12:11 AM   #2
Guru
 
Portage_Bay's Avatar
 
City: Coupeville Wa.
Vessel Name: Pelorus
Vessel Model: Californian 42 LRC
Join Date: Oct 2015
Posts: 1,320
Sticks can't be wrong any more than a tape measure can be wrong. They simply measure depth of liquid in the tank. If your tanks are cubes then no calibration is needed.
__________________

__________________
Some things are worth doing simply because they are worth doing.
Portage_Bay is online now   Reply With Quote
Old 11-30-2020, 12:14 AM   #3
Senior Member
 
Juliet 15's Avatar
 
City: Bellingham
Vessel Name: Knot Hours
Vessel Model: Hatteras 58 LRC
Join Date: Feb 2019
Posts: 102
Unfortunately, this text can be wrong and some boats. It really depends on where the hole that you were dipping the stick into is located on the tank. A small amount a list one way or another will come up with a different reading all together. With my boat I found if the wind blew strongly from One Direction or if I had the boat loaded more forward or aft I could get different readings that with some times vary significantly. I ended up putting some fuel sender's in the tanks that I had to calibrate by slowly filling them.I don't know the name of it, but one mechanic told me that there are sensors you can put at the bottom of the tank that will literally sense the number of gallons due to the weight on top of the sensor. I might look into that.
Juliet 15 is offline   Reply With Quote
Old 11-30-2020, 08:21 AM   #4
Guru
 
Group9's Avatar
 
City: Bay Saint Louis, Mississippi, (or where the anchor drops)
Vessel Model: 1973 42 Bertram MY
Join Date: Sep 2013
Posts: 1,243
Quote:
Originally Posted by Juliet 15 View Post
I don't know the name of it, but one mechanic told me that there are sensors you can put at the bottom of the tank that will literally sense the number of gallons due to the weight on top of the sensor. I might look into that.
I need to replace my senders. That is an interesting concept.
__________________
"It's the tides. They can work for you, and they can work against you. And, confidentially, I've had this problem with the tides before." Captain Ron
Group9 is offline   Reply With Quote
Old 11-30-2020, 09:00 AM   #5
Guru
 
Portage_Bay's Avatar
 
City: Coupeville Wa.
Vessel Name: Pelorus
Vessel Model: Californian 42 LRC
Join Date: Oct 2015
Posts: 1,320
I too need to replace my failing electro / mechanical swing arm senders. Unlike OP's situation access to the tank tops is not too bad, not easy, but not to $$$ to get at.

Maretron has a pressure sensor system Maretron fluid pressure monitor but I don't have a Maretron network system installed with no plans to.

Hippocampus mentions in another thread he's happy with the Philippi tank monitoring system. Like Maretron it looks like a network is needed. Philippi's offers different kinds of sensors but it looks like all will require access to the top of the tank. No link posted because I have yet to find a vendor who sells all the bit n pieces needed to put it together.

I have yet to dig into the tech issues deeply enough to know if Maretron or Philippi require the use of proprietary networks or will run on non-proprietary NMEA200 or CanBus networks.

With access to the top of the tank Centroid or Kus products will work and they do not require a network. They are hard wired and use old style gauges. Both of these are designed to drop into the standard flange used on the old style swing arm sensors making fitting to the tank easy peasy. I'm leaning towards one of these two. It seems many of the problems encountered with the old systems are not just the swing arm mechanism but bad connections wires. If I go this route I'll pull new wires at the same time.

If the tanks are not metal you may be able to use SCAD

There's always the Tank Tender. Beautifully simple, no wires, no network. Just air pressure. But, access to the top of the tank is needed.

I've just started looking at ultrasonic systems. These too will require access to the top of the tank.
__________________
Some things are worth doing simply because they are worth doing.
Portage_Bay is online now   Reply With Quote
Old 11-30-2020, 09:36 AM   #6
Guru
 
Portage_Bay's Avatar
 
City: Coupeville Wa.
Vessel Name: Pelorus
Vessel Model: Californian 42 LRC
Join Date: Oct 2015
Posts: 1,320
I've been thinking about this post. I think your mechanic is barking up the wrong tree. As your tank tips from listing or trim the fuel will be deeper at the low point, shallower at the high point. It doesn't matter what is used to read that level at that point it will read what it sees. This applies to old style electro / mechanical sensors, capacitance based sensors and air pressure systems. Or even what your mechanic recommends, liquid pressure. To envision this imagine you can tip the tank enough that at the sensor point there is no fuel, it will read empty. Now tip the tank enough that the fuel touches the top of the tank, it will read full. Don't be fooled by the promise the pressure sensor will read the tank volume regardless of list or trim. Pressure from a liquid is only for the height of the liquid above the sensor, not the volume. Fill a 1000 gallon tank to 12" and a pressure sensor will read 12" of pressure. Fill a 2" pipe to 12" and the pressure sensor will still read 12" even though the volume of the pipe is 0.1632 gallons!

You could eliminate errors due to list by putting the sensor point or dip stick hole in the center of the tank athwartships. The same with eliminating errors due to fore and aft trim. To eliminate both you'd need to put the sensor or dip stick hole in the center of the tank athwartships and fore / aft.

Your avatar shows a 58 ft boat. Unless the tanks are very low, wide and long I can't imagine the normal list or trim you encounter would greatly change the tank readings. The mechanic's recommendation to go to a pressure sensor system may well give you better readings. But not because it does a better job of dealing with list or trim. It will give better readings because there is something wrong with your present system.



Quote:
Originally Posted by Juliet 15 View Post
Unfortunately, this text can be wrong and some boats. It really depends on where the hole that you were dipping the stick into is located on the tank. A small amount a list one way or another will come up with a different reading all together. With my boat I found if the wind blew strongly from One Direction or if I had the boat loaded more forward or aft I could get different readings that with some times vary significantly. I ended up putting some fuel sender's in the tanks that I had to calibrate by slowly filling them.I don't know the name of it, but one mechanic told me that there are sensors you can put at the bottom of the tank that will literally sense the number of gallons due to the weight on top of the sensor. I might look into that.
Attached Thumbnails
Tank sensors.jpg  
__________________
Some things are worth doing simply because they are worth doing.
Portage_Bay is online now   Reply With Quote
Old 11-30-2020, 09:58 AM   #7
Guru
 
City: gulf coast
Join Date: Jun 2014
Posts: 3,441
Is the gauge stable when the boat is at rest?

The simple way to measure the tank is when filling it with a metered dispenser. Gauges working properly are very repeatable but not too accurate.

Get the fuel level down low then add fuel while recording the gauge readings. It will usually always read the same every time and you will know the amount of fuel added to get that reading.
bayview is offline   Reply With Quote
Old 11-30-2020, 10:27 AM   #8
Technical Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 6,176
Electric senders/gauges are notoriously inaccurate. Some are ok if quality and set up properly, but most the accuracy sucks.

If you can't easily remove the senders due to poor access, you are stuck with what you have.

Fortunately you can dip stick your tanks. After a while of use, you will figure out what the gauge readings mean relative to stick readings.

While the elec gauges are generally not accurate, they generally are repeatable.

So dip tanks at beginning of a trip, dip when shut down, dip when adding fuel. Eventually you will be see what gauge reading corresponds to stick readings.

On my ride I have no gauges. Stick only. 10gal/inch. I know exactly how much fuel I have before cranking up, and I have run the boat enough to know the burn rate, so it is easy peasy.

Seen way too many boats run out with gauge showing 1/4 tank.

You are fortunate that you can dip your tanks. Many boats can not.
Ski in NC is offline   Reply With Quote
Old 11-30-2020, 10:38 AM   #9
Veteran Member
 
City: KENNEBUNKPORT
Vessel Name: Clairrann
Vessel Model: Grand Banks 36
Join Date: May 2019
Posts: 28
I can't dip the tanks nor do I have any senders in the tanks. In actuality, I don't need either and have never even tried to add senders. Why? I know how much the engine/boat burns for fuel since I have always monitored engine hours and fuel fill-ups (always best to start w/full tanks). A little simple math - gallons to full / hours run - gives you the run-rate of fuel use. I have always been able to come within 10 gal if estimating a fill-up and since that's over 400 gallons of capacity it's a pretty good track record. As with most boat owners I never let the tanks get below about 1/4 capacity there's always plenty of wiggle room ... and in reality the fuel rarely gets below 1/2 capacity. I like to keep things simple, that's my ten cents.
Scrib is offline   Reply With Quote
Old 11-30-2020, 10:46 AM   #10
Senior Member
 
Solly's Avatar
 
City: Solomons MD.
Vessel Name: Sun Runner
Vessel Model: 1985 Mainship 34 Trawler MK III
Join Date: Mar 2018
Posts: 364
Quote:
Originally Posted by Scrib View Post
I can't dip the tanks nor do I have any senders in the tanks. In actuality, I don't need either and have never even tried to add senders. Why? I know how much the engine/boat burns for fuel since I have always monitored engine hours and fuel fill-ups (always best to start w/full tanks). A little simple math - gallons to full / hours run - gives you the run-rate of fuel use. I have always been able to come within 10 gal if estimating a fill-up and since that's over 400 gallons of capacity it's a pretty good track record. As with most boat owners I never let the tanks get below about 1/4 capacity there's always plenty of wiggle room ... and in reality the fuel rarely gets below 1/2 capacity. I like to keep things simple, that's my ten cents.
+ 1 for this.
Fill the tank run for 10 hours and refill. Burn per hour.
Then all you have to do is keep track of engine hours.
Solly is offline   Reply With Quote
Old 11-30-2020, 12:12 PM   #11
Guru
 
firehoser75's Avatar
 
City: Nanaimo
Vessel Name: former owner of "Pilitak"
Vessel Model: Nordic Tug 37
Join Date: Feb 2018
Posts: 1,651
Quote:
Originally Posted by Solly View Post
+ 1 for this.
Fill the tank run for 10 hours and refill. Burn per hour.
Then all you have to do is keep track of engine hours.
+2.
Started doing this with my first boat, a sailboat. The fuel gauge read "full" until the tank got fairly low, so was next to useless. Start with a full tank and then track engine hours. Next fill, calculate useage in gallons per hour (or some other volume like litres). Gallons added to refill divided by engine hours. After a few fill ups you will have a fairly accurate number.

On my Nordic Tug, I have a Tank Tender and tank sight tubes. My "manual method" is just as accurate as the TT and sight tubes. All 3 methods are usually within a couple of gallons of each other.
__________________
Tom
Nanaimo, BC
firehoser75 is offline   Reply With Quote
Old 11-30-2020, 12:24 PM   #12
Guru
 
Portage_Bay's Avatar
 
City: Coupeville Wa.
Vessel Name: Pelorus
Vessel Model: Californian 42 LRC
Join Date: Oct 2015
Posts: 1,320
Your method is great in that it doesn't depend upon any hardware. To make it work you have to run at the same engine RPM all the time to get the level of accuracy you have achieved. I wish I could use your method but I need / want to vary engine speed from 1000, sometimes as low as 800 and up to 2000. The burn rate on my engines nearly doubles from lo to hi. I've tried working out burn for a day's run by tracking time at different RPMs. Not worth the effort.


Quote:
Originally Posted by Scrib View Post
I can't dip the tanks nor do I have any senders in the tanks. In actuality, I don't need either and have never even tried to add senders. Why? I know how much the engine/boat burns for fuel since I have always monitored engine hours and fuel fill-ups (always best to start w/full tanks). A little simple math - gallons to full / hours run - gives you the run-rate of fuel use. I have always been able to come within 10 gal if estimating a fill-up and since that's over 400 gallons of capacity it's a pretty good track record. As with most boat owners I never let the tanks get below about 1/4 capacity there's always plenty of wiggle room ... and in reality the fuel rarely gets below 1/2 capacity. I like to keep things simple, that's my ten cents.
__________________
Some things are worth doing simply because they are worth doing.
Portage_Bay is online now   Reply With Quote
Old 11-30-2020, 12:53 PM   #13
Guru
 
Ken E.'s Avatar
 
City: Bellingham WA
Vessel Name: Hatt Trick
Vessel Model: 45' Hatteras Convertible
Join Date: Nov 2016
Posts: 1,543
Quote:
Originally Posted by Solly View Post
+ 1 for this.
Fill the tank run for 10 hours and refill. Burn per hour.
Then all you have to do is keep track of engine hours.
Same method I use. I refill based on hours as recorded in a log book. The number of gallons I take at the next fill-up is always what I expect.
__________________
Ken on Hatt Trick
Ken E. is offline   Reply With Quote
Old 11-30-2020, 01:06 PM   #14
Guru
 
rgano's Avatar
 
City: Southport, FL near Panama City
Vessel Name: FROLIC
Vessel Model: Mainship 30 Pilot II since 2015. GB-42 1986-2015. Former Unlimited Tonnage Master
Join Date: Oct 2007
Posts: 3,256
To the OP, do you know what senders you have? I am guessing WMA/KUS. If you are depending on a mechanic to gain access for you, yes, bigger bucks, but if you can accurately locate the sender's location on the top of the tank, it is quite often possible to use a four-inch hole saw to cut through the deck or whatever flat surface is above it to gain access. Hopefully, you boat's configuration can accommodate this approach. A standard plastic deck plate fits nicely into the hole when you are done to give it a proper finished look.

My personal experience with the WEMA/KUS senders is that both only one was connected to the console gauge, and it was making the needle on the gauge act whacky like yours does. Eventually, the needle stopped moving off "E" altogether. I replaced the gauge which tested as faulty and then replaced both tank senders and connected them both so I can read either tank at the gauge. Now the gauge agrees well enough with the sight gauge which I use to confirm the console gauge, especially at low levels.

It was alluded to earlier, but are your tanks possibly wider at the tops like a lot of installations?
__________________
Rich Gano
FROLIC (2005 MainShip 30 Pilot II)
Panama City area
rgano is offline   Reply With Quote
Old 11-30-2020, 01:45 PM   #15
Guru
 
City: gulf coast
Join Date: Jun 2014
Posts: 3,441
Ski:

IMO you are correct that gauges are inaccurate but they are usually very repeatable.

That is they will give the same reading with the same fuel level every time.
Just ignore the indicated levels and make your own calibration marks.
bayview is offline   Reply With Quote
Old 11-30-2020, 01:48 PM   #16
Guru
 
City: gulf coast
Join Date: Jun 2014
Posts: 3,441
Gallons per hour sounds nice but since speed, engine, bottom, and sea conditions may vary from time to time calibrating your gauges is a good check.
bayview is offline   Reply With Quote
Old 11-30-2020, 11:35 PM   #17
Member
 
City: Vancouver BC
Join Date: Nov 2020
Posts: 6
Yes my Drifter has a very accessible and straight into the tanks which are XYZ boxes but no with way to access the top. I can see but I cannot even get there.

I like to thrust on instruments (sounder, compass, tach, etc) but it seems I will have to calibrate the gauges AND myself to deal with this differently. It will be okay.

Thank you
Catam is offline   Reply With Quote
Old 12-01-2020, 12:03 AM   #18
Senior Member
 
Spinner's Avatar
 
City: Seattle
Vessel Name: Spinner
Vessel Model: 2003 Nordic Tug 42
Join Date: Dec 2018
Posts: 402
I have those Maretron fuel level sensors and also their fluid flow (fuel burn) sensors. They run on a NMEA 2000 backbone.
__________________
Regards

Sue
42 Nordic Tug Spinner
Spinner is offline   Reply With Quote
Old 12-01-2020, 07:08 AM   #19
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 21,914
The Flow Scan style gauges will record fuel used , if you adjust them a few times you can get within 2 gal of fill required on a 100g tank.

The Tank Tender style of liquid measurement works for fuel, fresh water and black water.

tanktender.com

The original precision tank measuring system. One instrument measures from 1 to 10 tanks. It gauges the liquid level in water, diesel & holding tanks.
FF is offline   Reply With Quote
Old 12-01-2020, 10:48 AM   #20
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Join Date: Jan 2013
Posts: 6,522
I can offer up some info on the various Maretron alternatives, just so they are fully understood. You might find one that is an easy adaptation to your boat. I have used all of these approaches.



Yes, they are NMEA 2000 (N2K) based, but that doesn't mean you have to build a big network. A sensor, display, power tap, and few fittings will give you a functional system. It won't be cheap, but it might be cheaper than cutting access holes and recovering with inspection plates.


Maretron has 4 different ways to measure tank levels. Two are based on pressure, just like a tanktender, one utilizes an existing (or added) conventional resistive float sensor, and one is an ultrasonic level sensor.


One of the pressure sensors is submersible, and gets lowered into the tank from the top, typically through the opening vacated by an old sender. The sensor lies on the tank bottom, and the cable runs through a cover plate and sealing gland through the tank top opening. The sensor then connects to a fluid pressure monitor (FPM100), and gets calibrated to report how many gallons or liters remain in the tank, based on the head of fluid above the sensor. One nice thing about this sensor is that the attached cable is flexible so the sensor can be lowered into the tank without much headroom over the tank opening. These sensors work very well, give very accurate level sensing, and best of all, they work equally well with gray and black water.



The other type of pressure sensor gets screwed into plumbing at or below the bottom of the tank. These can only be used if there is some sort of port or fuel draw from the bottom of the tank. It doesn't work if all fuel is drawn out from the top of the tank. The sensors have a 1/4" threaded end, and you need to tee into the existing plumbing somewhere. The location doesn't have to be right at the tank, but can also be further down the plumbing line. It just needs to be open to the tank, and at or below the tank bottom. These can be really easy to install if there is accessible plumbing that you can tee into. Like the other pressure sensor, this type connects to an FPM100. These are extremely accurate and reliable.



The next approach is a Tank Level Adapter, or TLA100. It gets wired to a conventional resistive sender. The advantage over a simple gauge display is that it can be calibrated to report fuel level in gallons or liters, and can accommodate irregularly shaped tanks. This approach is good if you want to use an existing float sensor, but accuracy is only as good as the float sensor, which generally isn't all that great.



The last approach is a replacement sender, but one that senses the fluid level ultrasonically rather than via a float. Calibration capabilities are the same as all the other approaches. I have only used these on black and gray water, and they worked very poorly. So poorly that I removed them. I know people first hand who have used them on clearer fluids like fresh water and fuel with much better success, though diesel foaming can be an issue under some circumstances. The bottom line is that I don't use these anymore. Sensing via pressure sensors works much better, and can be done from the top or the bottom of the tank, so there is just no reason to use an ultrasonic sensor when there are better alternatives.
__________________

__________________
MVTanglewood.com
twistedtree is online now   Reply With Quote
Reply

Tags
fuel gauge

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



» Trawler Port Captains
Port Captains are TF volunteers who can serve as local guides or assist with local arrangements and information. Search below to locate Port Captains near your destination. To learn more about this program read here: TF Port Captain Program





All times are GMT -5. The time now is 05:59 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012
×