24. THE GIAR PROCEDURES
 
Commercially the symbols O.B.Q. mean the liquid cargo remained on board and calculated prior the commencement of loading operations; this quantity, normally calculated in cubic metres, therefore must be subtracted from the total cargo quantity calculated on board. This is the reason why the calculation of O.B.Q. is very important. An incorrect calculation of O.B.Q. is many times the really cause of disputes between the Master/Owner and the refinery representative acting on behalf of the shippers. Many years passed to find a correct calculation of the O.B.Q. without a good result especially in all wing cargo tanks where internal structures follow the shape of the vessel.
The I.P. (Institute of Petroleum) in the last years, published a formula named the "WEDGE FORMULA". At first everybody applied this formula to calculate the O.B.Q.but after many ship's Master agreed this formula to be correct only in the calculation of O.B.Q. in the central cargo tanks. At moment, many ship's Master are rejected to calculate wing cargo tanks by using the "Wedge Formula" and other are obliged to use it as per special clauses reported in the Charter Party in which the quantity in cubic metres calculates using the "Wedge Formula" must be subtract from the freight the cost of O.B.Q. remained on board.
In all other cases, ship's Master are instructed from Owners to reject the O.B.Q. quantity calculated by the shippers representative or by the surveyor acting on behalf of the refinery, using the "Wedge Formula" and and also do not sign the "Dry Tank Certificate" where is indicated the quantity of the O.B.Q. The symbols R.O.B.(REMAINED ON BOARD)is the quantity remained on board on the completion of the discharge; this is different of the O.B.Q. i.e. the quantity remained on board prior to loading operation. On comparing both said quantity, it is very easy to calculate the quantity received on board as per Bill of Lading quantity.
The "GIAR PROCEDURES" considers the shape of wing cargo tanks and the results are very splendid.The "GIAR PROCEDURES" calculates the O.B.Q. prior to loading operation and also the R.O.B. after the completion of the discharge, for each cargo tank in few seconds.
This program gives the following solutions:
1) Ship listed, with a very small liquid quantity in the bottom of cargo tanks.
2) Ship listed, with more liquid cargo in the bottom of cargo tanks. The liquid laps also the opposite side of the cargo tank.
3) Ship listed, with liquid cargo lapping the opposite side of cargo tank and also the forward part of it, with trim by the stern.