VESSEL MOTIONS AND CARGO BEHAVIOUR. Mr Owen Lofthouse Rio Tinto

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1 VESSEL MOTIONS AND CARGO BEHAVIOUR Mr Owen Lofthouse Rio Tinto

2 Section Outline Vessel Motions and Forces Introduction Vessel Size Routes Results Cargo Observations Australian Bauxite Brazilian Bauxite Malaysian Bauxite Guinean Bauxite 2

3 Vessel Motion and Forces - Introduction Bauxite analysis builds on for IOF work Voyage Simulations Vessel rigid body motions estimated using Strip Theory Speed loss estimated using Rankinesource method Together with Global Wave Statistics, operability plots were developed for a given ship in a certain ocean area SAFETRANS package used to make 300 to 900 voyages to simulate the potential voyages experienced by a vessel over its lifetime 3

4 Vessel Sizes Based on the fleet used to carry the majority of seaborne traded bauxites Four vessel sizes were investigated Handymax ~ 50k DWT Panamax ~ 80kDWT Capesize ~ 170k DWT Capesize ~205k DWT 4

5 Routes Four Routes Investigated Malaysia to China Australia to China Brazil to China Guinea to China 5

6 Methods Individual Trips start at random points in 10 year database with wind, waves, swell and related forecasts 300+ Voyages simulate lifetime of vessel, including ballast return ~70 years for long routes, ~40 years for short routes Results include encounters with Tropical Revolving Storms Simulation yields information on the conditions encounter and motions experienced by the vessel Data on vessel motions includes roll, pitch, vertical and transverse accelerations Data is sorted and plotted as a frequency of exceedance or probability of encounter 6

7 Vessel Motion Results Australia - China Route 7

8 Vessel Motion Results Brazil - China Route 8

9 Vessel Motion Results Guinea- China Route 9

10 Handymax Motions 10

11 Cargo Observations Observations of behaviour of bauxite cargoes at and during loading, transit and discharge Includes on external (open ocean) voyages and internal (coastal) voyages Observations include; Visual record of cargo Measurements of cargo heights and volumes Bilge Pumping records Estimation of cargo bulk density and its change 11

12 Results Australian Bauxites Compaction % All Holds Average 2.7 Maximum 14.8 Minimum

13 Results Australian Bauxite Bilge Water Total Volume from Voyage (m³) % of cargo moisture reduction Average Maximum Minimum

14 Results Australian Bauxite Bauxite A1 Bauxite A2, A3 and A4 Laser Scanning % Compaction Before Bulk Density (t/m³) After Bulk Density (t/m³) % Compaction Before Bulk Density (t/m³) After Bulk Density (t/m³) Average Maximum Minimum

15 Results Brazilian Bauxite Brazilian Bauxite B6 Before Voyage Bulk Density (t/m 3 ) After Voyage Bulk Density (t/m 3 ) Average Maximum Minimum

16 Results Malaysian Bauxite Malaysian Bauxite C5 Before Voyage Bulk Density (t/m 3 ) After Voyage Bulk Density (t/m 3 ) Average Maximum Minimum

17 Results Guinean Bauxite Guinean Bauxite G2 Before Voyage Bulk Density (t/m 3 ) Average 1.66 Maximum 1.74 Minimum

18 Summary Vessel Motions and Forces Accelerations and motions in Handymax vessels are significantly greater than those of Capesize vessels, with Panamax sized vessels sitting in between Maximum acceleration experienced on the routes of Australia, Malaysia, Brazil and Guinea to China are similar and are governed by encounters with tropical revolving storms All vessels have a natural roll period of about 10 seconds or 0.1 Hz Hold 1 (forward hold) experiences the largest accelerations. The vessel accelerations are less than 1G, typically 0.1G. Cargo Observations Show that the bauxite cargo mass did not move significantly within a hold during the voyages undertaken. Cargo volume compaction varies from 0-15%, but is typically around 3%. Laser scanning/photogrammetry allows for precise determination (+/-0.5% volumetric) of cargo bulk density. Volumes of pumped bilge water indicate up to 0.5% reduction in the bauxite s moisture content during a voyage. Bilge pumping data as well as discharge inspections and observations show Australian bauxites are free draining. 18