Fuel Level indication

[Marco69]

I have Princess 33 fly bridge, while looking into the diesel tank I noticed the level sender is only 18" long. The tank is 25" deep at the point where the sender is placed, is this normal? it seems to me that I would have a lot of diesel in the tank even though the gauge reads empty. The tank is 250 Ltrs.
Please advise
Mark

 

[David2452]

Possibly a replacement bought on price or availability rather than suitability, a common sight. the other possibility is a V bottom tank where not much is left after the 18" so it's considered reserve.

 

[Marco69]

Many thanks

The tank is nearly rectangular with a slight slope 26" to 24", I guess a replacement was used. I need to check the length of the fuel take out pipe to be sure. If the take out pipe is 1" from the bottom do you think a sender 1-2" above this point would be ideal

Regards

 

[nigelmercier]

The instructions for VDO senders say to install them so they don't reach the bottom, no idea why. I've fitted a new bracket and a longer arm, and bent it so it is now full range.

 

[coopec]

I have Princess 33 fly bridge, while looking into the diesel tank I noticed the level sender is only 18" long. The tank is 25" deep at the point where the sender is placed,
Mark

Marco

I have no idea what is "normal" but surely 7 in (25-18) is too much? Having said that I wonder whether the last 3-4 inches would be usable when it is sloshing around in a choppy sea?

 

[nigelmercier]

Marco

I have no idea what is "normal" but surely 7 in (25-18) is too much? Having said that I wonder whether the last 3-4 inches would be usable when it is sloshing around in a choppy sea?

We are still talking about fuel, right?

 

[David2452]

Many thanks

The tank is nearly rectangular with a slight slope 26" to 24", I guess a replacement was used. I need to check the length of the fuel take out pipe to be sure. If the take out pipe is 1" from the bottom do you think a sender 1-2" above this point would be ideal

Regards

If, as I read from your post it's a tube type rather than a swinging arm then an inch or so above the dip tube is probably prudent. If possible start with an empty tank and note the gauge position when filling it, they can be a bit misleading otherwise.

 

[coopec]

We are still talking about fuel, right?

Yes Nigel, it is the fuel tank that Marco is talking about. I don't follow your post. Please explain!!

 

[Lodesman77]

I have no idea what is "normal" but surely 7 in (25-18) is too much?

Personally I would say it's about right...

 

[Sandy]

I use a stick.

Marked off with cuts for 1/4, 1/2, 2/4 and 4/4 full. Never fails.

 

[coopec]

Personally I would say it's about right...

Yes, thinking about it I am sure you are right. I would not want to start sucking air, particularly in the middle of a critical manoeuvre (such as docking) or negotiating a tidal pass of an atoll somewhere in the South Pacific.

 

[William_H]

Well I understand wat Nigel is aluding to but also will not explain (keep the p[arty clean).
I am surprised OP does not know how his fuel guage reading relates to actual fuel quantity. he might suspect but needs to know.
On light aircraft every 3 years the tanks are drained then the guage readings are compared to actual fuel put in from a calibrated pump. If ther are discrepancies or the guage is shown as 1/4 1/2 3/4 etc then a calibration card is prepared and attached next to the guage.
Of course there is always fuel in, when the guage reads empty. There is also a quantity known as unusable fuel which is the amount in the tank when the quantity is so low as to be unreliable (various attitudes) but is often actually usable. Lastly there is the quantity which is undrainable ie only able to be drained from the water drain point which is in effect the water holding part of the bottom of the tank. While this is all for aircraft, the system is similar although outcomes not so drastic if you run out. A boat operator would do well to kow exactly how much fuel he has available especially a MOBO. good luck olewill

 

[coopec]

the last 3-4 inches would be usable when it is sloshing around in a choppy sea?

Nigel

Yes, I was just dreaming (again):miserable::miserable:

 

[cliff]

I use a stick.
Marked off with cuts for 1/4, 1/2, 2/4 and 4/4 full. Never fails.
Cynical Scots engineer who sails a Mirage 28

2/4? engineer? frequently fails more like!

 

[single]

1/2, 2/4............brilliant.

 

[Sandy]

2/4? engineer? frequently fails more like!

Fingers not working as fast as my brain again. OOps.