This document discusses techniques for calculating ballast water volume using sounding table extrapolation. It describes how duty officers currently use sounding tables and corrections to determine ballast water levels, but this can be inaccurate for over-trimmed vessels. The research aims to verify if extrapolating sounding table data using equations can more accurately calculate ballast tank capacities. The results showed that sounding table data can be converted to equations incorporating trim levels. Extrapolating this data using midpoint values produced errors of zero, providing an accurate method for determining ballast water volumes.

1. 3rd ICMET 2019
Surabaya 21 November 2019 – Sheraton Hotel Surabaya
Ballast Calculation Techniques using Extrapolation
Anggara Purwandaru1
, Hadi Supriyono2
, Sri Suyanti3
Email: anggarapurwandaru@gmail.com1
hadispri3@kap3b.net2
srisuyantij5@gmail.com3
1,2,3
Merchant Marine Polytechnic of Semarang, Jl. Singosari 2A, Semarang City, 50242,
Indonesia
Abstract: Duty Officer used sounding table correction in determining ballast water
volume, when the Draft Survey are carried out on bulk carrier vessel. In case of over
trimmed vessel, the officer couldn’t determine accurate ballast calculations. This
research aimed to verify if the sounding table extrapolation is the alternative to
calculate ballast tank capacity. Data on sounding table belong to their variables such as
trim and volume, then it converted into a general equation. The reading of the range
data and matrix calculations on sounding table data using SCILAB 6.0.2 to generate
coefficients. The Mean Absolute Error (MAE) conducted the error obtained by models of
equation. The result of this research showed that (1) The sounding table data can be
determined as equations (2) Trims over the table and coefficients which are converted
into the equation produce new volumes (3) The error of the midpoint extrapolation
showed 0, then it can be used to calculate the ballast water volume.
Key words: Extrapolation, Sounding table, Trim, Volume.

2. 3rd ICMET 2019
Surabaya 21 November 2019 – Sheraton Hotel Surabaya
Vessels are all means of transport that can carry objects and people and operated in
water areas, be it the sea, river, or lake. The vessel with certain forms and types, which
are driven by wind power, mechanical power, other energy, withdrawn or suspended,
including a powerful vehicle dynamic support, the vehicle below the water surface, and
floating structures that do not move. Draft survey as requirement of loading and
unloading are carried on board involving Chief Officer or Duty Officer and the surveyors
payload to obtain the information about the ship’s stability and the amount of cargoes
that have been unloaded or loaded by means of viewing vessel’s draft, then performed
computerized or manual calculations supported by the data, as the results of deductible
sounding (fresh water, drinking water, ballast water, lubricating oil, fuel oil and diesel
oil), ship’s constant, vessel’s lightweight, the specific gravity of water around the ship
when implementing draft survey and clinometer readings. These data are entered into
formulas in accordance with the Stability Booklet or Ship's Loading Manual Book, then
do some corrections such as draft correction, trim corrections, and use the tables
include hydrostatic table and sounding table.
Volume is the content or the capacity of an object or space of three dimensions include a
cube, a prism, cylinder, cone, and sphere. The units used by volume in International
Standard as cubic meters (m3
) and in Imperial as cubic feet (ft3
). Volume object is
determined as area A, the area of the base multiplied by the height h (Edwin & Dale,
2005), namely:
V = A .h (1)
If an object has an irregular shape, then its volume can be measured with a measuring
cup so that the volume of liquid displaced is equal to the volume of submerged objects.
But it also can be applied to objects that have normal shapes.
The ballast water is a liquid that increase maneuver capabilities with the sinking ship
propellers, reducing the effects of wind on the hull, and for the stability of the vessel
(George, 2002). Ballast water is used on ship has a density (ρ) that vary due to filling in
a different water area. Ballast water from open sea has a Specific Gravity (SG) 1,025
(Barrass, 2001) , rivers or freshwater lakes SG have ≤ 1, slightly different from the
estuary which is a meeting between the freshwater to saltwater. The dock water SG
usually between 1.0 - 1.025. Ballast water usually kept in Ballast Water Tank which
shown in figure 1.
Figure 1. Ballast Water Arrangement Plan. Source: MDM BROMO Ballast Tanks Plan,
drawing: author
Extrapolation is a method for determining the data beyond the data which already
known, in contrast to the decisive interpolation of data between a stretch of two pieces
FPT