On a ship, it is very important to keep the updated record of the quantity of liquid (in all forms) present in the tanks for the following reasons:
1) Port state authority can randomly check and demand the record of oil and bilge on board. They can randomly check the micro-biological content of ballast water present onboard.
2) For proper operation of machinery, different grades of lube oil should always be present onboard. Even a shortage of crankcase oil of any machinery can bring the ship to standstill.
3) A ship normally completes a passage of ports. For proper passage planning it is very important to have the record of fuel and diesel oil onboard to quote for the next bunkering operation and to avoid any kind of marine pollution by overflow of oil.
4) In oil tanker carrying oil as a primary cargo, continuous monitoring of sounding of all tanks is very critical at the time of loading of cargo to avoid a single drop of oil going overboard which is a criminal offence.
5) Many ports have there own regulation for not exceeding waste water onboard above a certain limit. An exact record is required to follow the same.
6) For SECA area and now in most of the countries with sulphur emission norms, true quantity to be recorded for all grades of fuel oil present onboard.
7) When Ships bilge water is processed and discharged through oily water separator, correct entry of sounding, quantity discharged and retained onboard is to be recorded.
8) When onboard sewage holding tank is emptied in mid sea, sounding, quantity and amount discharged to be recorded.
9) Quantity and quality of ballast water to be recorded for ready reference of chief officer for stability, berthing and canal crossing etc.
10) All tanks quantities which include fuel and lube oil should be handy with chief officer for executing next loading plan.
How to take sounding?
Follow the steps mentioned below to take sounding on a ship using the sounding tape.
1) Make sure the bob is tightly held with the tape using a strap hook. Ensure that the tape is not damaged anywhere in between to avoid dropping of bob or tape inside the pipe.
2) Know the last reading of the tank in order to have a rough idea whether to take sounding or ullage.
3) Apply water/ oil finding paste to get exact readings.
4) Drop the tape inside the pipe and make sure it strikes the striker plate.
5) Coil up the tape and check for impression of paste and then note the sounding.
6) Check the trim and list of the ship to read the correct reading for volumetric content of the ship.
7) Note down the sounding in the record book with signature of the officer in charge.
Sounding Measuring Tape
For Manual measurement of sounding, a measuring tape normally made up of brass and steel with a weighted bob attached at the end of the tape is used.
Sounding pastes are also available for both water and gas oil which highlights the level of fluid in tape.