SHIP TO SHIP OPERATIONS MONITORING SYSTEM USING HIGH ACCURACY DGPS

8th IFAC Conference on Control Applications in Marine Systems Rostock-Warnemünde, Germany September 15-17, 2010

       

SHIP TO SHIP OPERATIONS MONITORING SYSTEM USING HIGH ACCURACY DGPS  

Hiroyuki Oda*, Etsuro Okuyama* and Etsuro Shimizu**  

* Akishima Laboratories (Mitsui Zosen) Inc. 1-50, Tsutsujiga-oka 1-chome, Akishima, Tokyo, 196-0012, Japan ** Tokyo University of Marine Science and Technology 1-6,Etchujima 2-chome, Koto-ku, Tokyo, 135-8533, Japan  

Abstract: The berthing and ship to ship operations are the most difficult and delicate phase for large tanker and LNG carrier operators and crew. From the viewpoint of the safety operation, it is important to watch motion under berthing operation at real time. Recently navigation systems using DGPS with electric chart are commonly equipped on almost of all vessels, but we focus at berthing operation and relative information between ship and ship to ship. This paper proposes ship to ship operations monitoring system (STSM) with high accurate DGPS. The STSM has a few modes, e.g. approaching docking and lighting mode for ship to ship operation. This paper introduces STSM with high accurate DGPS and full scale experiments. Copyright © 2002 IFAC 

Keywords: LNG carrier, Tanker, Ship to ship operations, Monitoring system, DGPS      

1. INTRODUCTION

2.1 StarFire- WADGPS (R. Hatch et al. ,2002)

It is important to watch vessel’s motion with dangerous load e.g. large tanker or LNG carrier under berthing and ship to ship manoeuvre at the good accuracy real-time from a viewpoint of safety operation. The berthing and ship to ship manoeuvring are the most difficult and delicate phase of vessel's navigation. For such demand, ship to ship operations monitoring system (STSM) with high accuracy differential GPS (DGPS) is possible to measure the vessel position at high-precise and realtime. To meet such requirements of safety operation, we present the STSM with high accuracy differential GPS. This paper firstly introduces high accuracy differential GPS, secondly presents ship to ship operations monitoring system (STSM) and the last shows full scale experiments and the results. 

The StarFire Wide Area DGPS (WADGPS) has been in progress from a set of regional DGPS networks which provided high accuracy service over independent continental areas to a robust unified global network offering unprecedented accuracy. This global network provides uniform sub decimeter real time service over almost the entire Earth. It is based on technology developed by the Jet Propulsion Laboratory (JPL) for the National Aeronautics and Space Administration (NASA). Figure 1 shows overview of the StarFire WADGPS architecture.

2. DGPS AUGMENTATION SYSTEM

Now there are other similar wide area DGPS systems all over the world. These are federal aviation administration’s Wide Area Augmentation System (WAAS), Europe’s EGNOS, and Japan’s MSAS. 

978-3-902661-88-3/10/$20.00 © 2010 IFAC

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Fig.1. StarFire-WADGPS

(http:// www.navcomtech.com) 10.3182/20100915-3-DE-3008.00021

CAMS 2010 Rostock-Warnemünde, Germany, Sept 15-17, 2010

There are several key characteristics which enable the extremely high accuracy and robustness of the StarFire system: * GPS measurement data from a global network of dual frequency reference receivers. * Modelling of all significant error sources. * High quality dual frequency mobile receivers. * Highly redundant measurement data, processing structures, and communications links. In combination, these characteristics offer a unified, robust, real time, global capability. StarFire has been developed and operated by NavCom Technology, Inc. and broadcasts the correction stream over three INMARSAT satellites to provide global coverage.

Fig.3. Block Diagram of STSM 3.2 Function and operation of STSM

2.2

MASA-DGPS STSM with applied StarFire-WADGPS (H. Oda et al, 2009) is shown in Figure 4. The mainly function of STSM as GPS reception, communication between ship to ship.

MTSAT Satellite-based Augmentation System (MSAS) provides GPS augmentation information to aircraft through MTSAT (Multi-functional Transport Satellite) located at 36000km above the ground over the equator. MSAS that is shown in Figure 2 generates GPS augmentation information by analyzing signals from GPS satellites received by monitor stations on the ground.

STSM provides the following information; * Relative distance between and vessel and way point. * Final berthing position and recommendation route. * Dangerous line and alarm. * True vessel heading, speed direction of movement. * Wind, wave and sea current. Performances of this system are as follows; * High accuracy in sub meter order. * Shi position, speed can be monitored at real time. * The object vessel’s data can be recorded. * Data can be monitored with PDA at the wing.

Fig.2. MTSAT Augmentation System (MSAS) 3. SHIP TO SHIP OPERATIONS SYSTEM This paper shows the STSM and applications of this system for which ship to ship operation. 3.1 Ship to ship operations system overview

Fig.4. Ship to Ship Operations System (STSM)

The STSM has efficient functions of good performance to watch positions and motions of the ship utilizing the GPS real-time. Depending on the function of StarFire-WADGPS, it is possible to measure the position at the accuracy of sub meter. The STSM basically consists of GPS receiver and fiber optical gyroscope and portable monitor unit (H. Oda et al, 2004). The block diagram of STSM is shown in Figure 3. STSM is installed in Shuttle while approaching to VLCC. Information of VLCC that navigates by a constant speed and course acquires AIS (Automatic Identification System) are concatenated to STSM. The target VLCC is selected from AIS information by the ship recognition number.

3.3 Applications of STSM Applications of ship-to-ship operations for cargo transfer are supposed to increase in the future. Future development of Northwest Russian onshore and offshore fields increasingly need ship to ship transfer from a fleet of smaller ice strengthened vessels to standard vessels for transport of oil and gas products to customers in Europe and US. The images of situation of ship to ship are shown in Figure 5. Figure 5 shows approach system to Floating LNG, which shows the position, heading and movement of Single Point Mooring, FPSO and shuttle tanker.

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CAMS 2010 Rostock-Warnemünde, Germany, Sept 15-17, 2010

Table 1 Principal particular of actual ships

Ship to ship operation

Ship Length Breadth DW

APOLLONIA 333 m 58m 308,200 t

CHALLENGER 240 m 42m 105,000 t

Monitoring of approach and docking mode of STSM is shown in Figure 7. This figures show positions of VLCC and shuttle tanker, heading, movement of two vessels, relative ranges and relative/absolute docking speed. Especially at docking mode, docking speed and distance of bow, stern and centre can be monitored both PC and PDA (Personal Desktop Accessory).

Approach to Floating LNG (http://www.halliburton.com/)

Fig.5. Applications of Ship to Ship Operations System 

4. FULL SCALE EXPERIMENTS

4.1 Full scale experiment of STSM The actual ships for experiment are VLCC “APOLLONIA” and Shuttle “CHALLENGER”. The principal particular is shown in Table 1. Situation of ship to ship operations experiment at Mexico Gulf about 60 miles from Freeport are shown in Figure 6.

(Birds eye view : Approach mode)

(Birds eye view : Docking mode)

*Bow: Speed & Distance *Centre: Speed & Distance *Stern: Speed & Distance (Personal Desktop Accessory) Fig.6. Ship to ship operations (Mexico Gulf) 64

Fig.7. Monitoring of Ship to Ship Operations System

CAMS 2010 Rostock-Warnemünde, Germany, Sept 15-17, 2010

The time histories of speed and distance are shown in Figure 8. Approach speed and distance shows relative speed of VLCC and Shuttle tanker. These results mean that steady approach speed is about 5.4(kts.) and relative distance between actual and object position is about 0 to 5(m). Docking speed and distance shows relative speed and distance of bow side. The result of docking steady relative speed is about 10(cm/sec.). The result of steady relative distance is about 5(m). A part of the result of the distance depends on the position where GPS antenna is set up and accuracy of the input value of fender size for the cause of a negative distance. It does not indicate collision condition. This outcome of the experiment represents the examination according to the development of STSM.

and vessel of STSM and Laser docking system fit well.

(Birds eye view : Berthing mode) 前後方向速度（船央）

Ahead speed (center)

[ kt ] 6 5.8 5.6 5.4 5.2 5 0

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(Docking speed and distance ：Bow) Fig.8. Ship to ship operations (Docking)

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4.2 Justification of STSM performance

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Approach speed of VLCC and LNG vessel crude carrier must be controlled to a few cm per second at berthing mode. The time series in Figure 9 are one of the results of STSM and Laser docking systems (Speedometer). In this figure, blue (thick) line is the results of using STSM and purple (thin) line is the results of using laser speedometer. From these results, both approach speed and distance between the berth

1600 time(sec)

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(Berthing distance) Fig.9. Comparison between STSM and Speedometer (Speed and distance : Berthing mode) 65

1600 time(sec)

CAMS 2010 Rostock-Warnemünde, Germany, Sept 15-17, 2010

5. CONCLUSIONS It is important to watch the vessel motion of dangerous vessels such as the large tanker and LNG carrier at the good accuracy real-time from the viewpoint of the safety operation at berthing and ship to ship operations. To meet such requirements of safety operation, STSM with applied global high accuracy GPS augmentation system is possible to offer the sufficient or necessary information such as distance and approach speed. STSM could provide a precious database with users for not only supporting the vessel’s safety operation but also the vessels managing system. It is convinced that STSM is needed for more helpful and safety operations. The database can be expected to operate in the following conditions by using STSM. The first is situated in approach manoeuvring and cargo handling operation under sea condition, the second is for a vessel management concerning ship to ship cargo transfer and crisis-management. 6. ACKNOWLEDGMENT A part of this research has been funded by the Norwegian Research Council through the international joint-industry research programme “Investigating Hydrodynamic and Control Aspects of Ship-to-Ship Operations”. Subagent Petro Trans Inc. in Houston, USA, is appreciated for the practical assistance in carrying out the field testing and the measurement programme onboard the tanker in their fleet in November 2009. The authors are grateful to staffs of Skuagen Petro Trans Inc. Also authors thank to crew for their help in implementing the STSM and their support in the field testing. REFERENCES R. Hatch, et al. (2002), StarFire: A Global High Accuracy Differential GPS System, Proc. of GPS Symposium 2002, Japan Institute of Navigation. H.Oda, et al. (2004), New Berthing Support System with StarFire DGPS, International Symposium on GNSS/GPS 2004. H.Oda, et al. (2009), New Berthing and Ship To Ship operation support system (NBSTS), ANC 2009.

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