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# Ships Tank Calibration

## Ships Tank Calibration

(OP)
I work on ships as a Marine Engineer. In ships I work, we use traditional method to check quantity in the ships oil tanks. Check the tank sounding using a sounding tape then check readings against Tank calibration book to find the quantity.
Any software programs in the market do this after entering tank sounding data to the Program? Any ideas will be greatly appreciated.
Thank you and best regards
Replies continue below

### RE: Ships Tank Calibration

Such a program would need to have knowledge of the tank's geometry.  Most of the ship's tanks I've seen are rectilinear at the top, but have odd shapes at the bottom, because of ... the bottom.

I can think of two ways to produce an analog of the calibration book, which I'm assuming you have lost:

1. Empty the tank, then fill it a barrel at a time, take soundings, and interpolate.

2.  Make a solid model of the tank's interior in AutoCAD or some other 3D CAD package, then slice the model at reasonable sounding increments, have the program calculate the volume of each slice.

Either way is a fair amount of work.

Mike Halloran
Pembroke Pines, FL, USA

### RE: Ships Tank Calibration

(OP)
Mike Halloran
Thank you. That gave me an idea where to start. Option no2 seems more attractive. I did not know AutoCAD has that capability. I have used the program only on two dimensional drawings.
Ahts

### RE: Ships Tank Calibration

These are used to calculate the overall vessel stability and longitudinal strength based (mainly) on the loadings in the various tanks and holds.

To do this, they usually have the tank calibration tables already in the computer (certainly for CARGO tanks). Then, if the user enters the depth of liquid in the tank, the computer calculates the weight and centre of gravity of the tank contents, for further use in the stability computations.

The input DEPTH of liquid can come from manual entry (by the sounding you refer to) or automatic tank level gauging instruments if fitted.

What age and kind of ship are you on ? Most modern ships have remote level gauging linked to such a computer.

For this system to be approved by the class societies for use in stability calculations the tank calibration data in it must be verified from the builder's original data.

As you almost certainly know the people on board ship who use these loading computer programs are the deck officers - not the engineering officers. I would suggest that (if not done already) you speak to your Chief Officer to see what you have onboard.

I apologise if you know all this.

### RE: Ships Tank Calibration

(OP)
Thank you JRMacGregor.
The ships I work are between than 12 to 30 years old. They do not have computers with calibration data already stored. We use Tank calibration tables (in paper format) to read the content of the tank. As you can imagine it is a time consuming and tiring task. I use a simplified excel sheet, still you need to read, make appropriate trim corrections, temperature corrections appropriate to the tank sounding to calculate the content.

As you say it is connected to the vessel stability and Chief Mate is doing all manually same a me. You clearly understand the issue, I am facing and please let me know if you aware of any software programs commercially available.

Thank you
Ahts

### RE: Ships Tank Calibration

Hello AHTS

There are many computer programs for ship stability.

One well known one is "Onboard NAPA". Another is BigChief from Marinteknikk in Norway.

Try also www.AutoSHIP.com
"formation design"
www.wolfsonunit.com
"Ship constructor"
LOCOPIA from SARC (Holland)

Regards

James MacGregor

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