Poster PO-46

PO-46.1

DEVELOPMENT OF “TANKER NAVI”GPS NAVIGATION SYSTEM FOR LNG TANKERS

Tetsu Shiota President

Teruaki Kitaura Manager, Electric Instrumentation Department

Shoichi Momiki Electric Instrumentation Department

Sakai LNG Co., Ltd. 3-1-10 Chikko Shinmachi, Nishi-ku, Sakai-shi

Osaka, Japan

ABSTRACT

To enhance safety of LNG tankers in berthing and unberthing, Sakai LNG has developed the “Tanker Navi”, a new berthing support system using GPS (Global Position System) technology. The big features of Tanker Navi are that it is compact, lightweight and extremely portable. It is the smallest berthing support system in the world in terms of size and weight, which materialized for the first time ever the concept of a portable monitor displaying various kinds of information.

The entire system weighs only 9.5 kg. Not only can it be easily carried onboard a tanker, setup is easy as well. The portable monitor connects to the main system via a wireless LAN and makes it possible to check berthing and unberthing information (bow/stern approach speed, remaining distance to berth), ship position, heading direction, ship speed, distance from shoals and obstacles, wind direction at berth, wind speed and wave height, while the pilot moves freely about the bridge wing.

Using this simple system, pilots can at any time get accurate information necessary to impart operating instructions.

Every time an LNG tanker enters or leaves the port, the route (PC video) is sent to the pilot office from the Sakai LNG Terminal by e-mail to help maintain and improve the operational skills of pilots.

Poster PO-46

PO-46.2

1. INTRODUCTION

Sakai LNG, an LNG receiving terminal in Osaka Japan, commenced its commercial operation in January 2006. It has a berth and unloading facilities capable of accommodating LNG tankers of 145,000 m3, three PC (prestressed concrete) LNG tanks with a capacity of 140,000 m3 each and six vaporizers (including one for backup) with a capacity of 135 t/hr each. It sends regasified natural gas mainly to neighboring power stations.

Sakai LNG is located in the Sakai-Senboku coastal industrial zone on Osaka Bay area. In order to minimize the dredge volume when constructing the berth, a dolphin type berth has been adopted and the berth was constructed around 500 meters north of the existing berth of a neighboring oil company. Because two berths were located nearby, the introduction of a GPS berthing support system was requested by national authorities in the process of approving the berth design in March 2003, in order to enhance the safety of pilot operation when berthing and unberthing.

To support pilot operation, Sakai LNG thought the unit should be compact, lightweight and mobile so that pilots themselves could install it for use not only inside the bridge but also on the bridge wings. We searched an existing product of such berthing support system, but we could not find a suitable one, therefore we determined to develop by ourselves.

In developing the system, we have established the following target functions to achieve.

• Compact and lightweight

• Weatherproof (easy to view in the sunlight, available in the rain)

• Wireless so as not to hinder pilot movements

• Battery-powered not to use the ship’s power

• 10 kg or less in total weight when brought onboard ship

• Easy setup that would enable system operation to start in about 10 min after the crew brings it up from a tugboat

• Tanker position with a margin of deviation of plus or minus 1 m

The target date for the completion of the development was set to October 1, 2005 so that the system could be available for the first LNG tanker for the initial cool down.

The Tanker Navi can retrace the berthing and unberthing of the LNG tankers at a given interval of time. We have also developed a computer software so that we can display the route of LNG tankers on desktop PCs. This software is also installed in the computer in the pilot office, and Sakai LNG sends the navigation data of every LNG tanker to the pilot office via e-mail so that they will contribute to improving pilot operation skills.

Poster PO-46

PO-46.3

2. BERTH LOCATION AND LAYOUT

(1) Berth Location. The berth of Sakai LNG is located 500 m north of the crude oil berth of Cosmo Oil Co., Ltd. The location of the berth is shown in Fig. 1-1.

Figure 1-1. Berth location at Sakai LNG Terminal

Hyogo

Nara

Sakai

Osaka

LNG Berth

Hamadera Passage

Cosmo Oil Berth

14 m depth line

Poster PO-46

PO-46.4

(2) Berth Layout. Sakai LNG terminal has two berths: one for LNG unloading that can accommodate an 80,000 DWT class LNG tanker (470 m total length, dolphin structure), and another for fuel oil loading capable of accommodating a 2,000 DWT class ship(105 m total length, dolphin structure).

The berths are shown in Fig. 1-2.

Figure 1-2. Berth plan

3. TANKER NAVI SYSTEM CONFIGURATION (COMPONENT SPECIFICATIONS)

Tanker Navi is a two-piece set of equipment. It consists of a base station that is located in the berth control room at the Sakai LNG Terminal berth and a mobile station that is carried onboard and installed on the port-side bridge wing of an LNG tanker.

The system configuration is shown in Fig. 2-1, while component specifications are given in Table 1.

Fuel Oil berth length = 105 m

MD5MD6

MD4

WPBD3BD2BD1

MD3MD2MD1 WP

LNG tanker

Fuel oil barge

LNG berth length = 470 m

MD5MD6

MD4

WPBD3BD2BD1

MD3MD2MD1 WP

Poster PO-46

PO-46.7

Figure 2-1. Tanker Navi system configuration

Table 1. Tanker Navi component specifications

(1) Base station components (2) Mobile station components

Component Specifications Component Specifications Computer CPU:Pentium4 2.8GHz Trunk Interface converter RS-422⇒RS-232C PC Panasonic CF-18 Modem AIWA PV-AF3361 Pilot monitor Panasonic CF-VDW07 GPS GARMIN Geko301 GPS antenna Wireless LAN antenna BUFFALO WLE-DAH GPS antenna receiver

Vector Sensor PRO

Wireless LAN access point BUFFALO WHR-HP-G54 GPS communication

cable 1 m

Cell phone au Casio, G'zOne TYPE-R Cell phone modem au Casio, cable C

Wireless LAN antenna BUFFLO WE-DAH

GPS battery AA x 8

Base stationPC

No.2

Base stationPC

No.1

Base station

GPS Antenna (Roof)

Wind direction and speed, wave height (Operation support system communication)

Laser measured distance (Approach speed meter communication)

RS-232C

RS-232C

Switch

LCD monitor

Mouse

Keyboard

Hub

Ship-Shore communication

Wireless LAN

USB

RS-232C

100V AC

Alarm contact

Wireless LAN

(Roof) GPS antenna kit

Existing system

RS-422

RS-232C

Color printer

Interface converter

GPS antenna

relay

RS-422

Modem

RS-232C Cel

l pho

ne

(CdmaOne switch)

Mobile station PC

Display terminal

Time correction

GPS

GPS with internal directional direction

CV-CF

For pilot

(Weak electric wave coupling)

Wireless LAN access point

NTT line

Wireless LAN card

Wireless LAN

antenna

192.168.2.29

LAN Wireless

Modem

Wireless LAN

antenna

Contact

Legend:

Mobile station

Wired

Poster PO-46

PO-46.8

(1) Base Station. The base station is duplicated using two computers so that operation can be maintained in the event that trouble shuts one down. This information is converted into an RS-232C signal by the interface converter before being imported by the base station computers. The acquired information is sent to the mobile station via a modem and wireless LAN antenna.

(2) Mobile Station. The mobile station consists of three parts, all of which are stored in a single trunk (H37 x W700 x D280 mm) with total weight of 9.5 kg. It runs on battery power.

a． GPS antenna kit integrates a GPS antenna and ship-to-shore communicator

The GPS antenna kit can be easily installed in a predetermined position on the port-side bridge wing of the LNG tanker using two clamps.

b． PC for computing acquired information

The PC is used as is housed within the trunk. It calculates LNG tanker position, speed, etc. The information is sent to the base station and displayed on a multipurpose CRT in the berth control room.

c． Pilot monitor for providing information to the pilot

The pilot monitor weighs 740 g and is worn around the neck of the pilot. Necessary information is sent from the mobile station by wireless LAN. Accordingly, since it does not require any cables, pilot can be freely moved between the bridge wing and inside the bridge with it.

Figure 2-2. GPS antenna kit

Poster PO-46

PO-46.9

4. SHIP-TO-SHORE COMMUNICATIONS

Ship-to-Shore communications between the base station and mobile station are based on constant two-way information exchange via cell phone and wireless LAN.

Tanker Navi gets on line about 10 km offshore from the Sakai LNG terminal, and communications with the base station are made on cell phone. However, as the cell phone may be unable to contact the base station because of poor radio wave conditions, the wireless LAN is also used from about 3 km to the berth control room.

A conceptual view of ship-to-shore communications is shown in Fig. 3.

Figure 3. Conceptual view of ship-to-shore communications

5. ALGORITHM FOR CALCULATING TANKER POSITION AND SPEED, AND ITS ACCURACY (PATENT RELATED)

5-1 Positional Correction (Patent Pending)

Position signals from GPS can jump anywhere between several tens of centimeters to several meters when switching satellites (normally 3 or 4 are used). As the movement of a large ship like an LNG tanker within a short period of time can be deemed to be a linear uniform motion, we can approximate the position using the speed computed from the

Telemeter

モ

ニ

本

体

Wind direction/speed, effective wave height (Communication speed: 9600 bps)

Position information (Communication speed: 1 Mbps)

Modem

Meter panel (3rd floor of wharf monitoring station)

To stop line calculation When near

When far off

Pilot monitor

Mobile station

PC

Position information (communication speed: 9600 bps)

Tanker Navi (Onboard) au antenna

NTT line

Aerovane

Wireless LAN antenna

Effective wave height

Wind direction/speed, effective wave height, alongside pier speed: (Communication speed: 1 Mbps)

Tanker Navi base station PC

(Berth control room)

Poster PO-46

PO-46.8

recent data. A jump can be identified by comparing the such computed position data and the data obtained from GPS every second.

If a jump is identified, the error caused by the jump is averaged by correcting to the assumed position based on uniform linear motion, calculating the average amount of jump with every jump and approximating the jump correction to the jump average. The GPS itself has a guaranteed accuracy of ± 5 m, but this processing improves it to ±1 m. A flowchart of the GPS position correction process is shown in Fig. 4-1, while an example of positional correction is shown in Fig. 4-2. With Tanker Navi, the minimum jump ε is 2 m, and the maximum corrected amount φ is 0.1 m.

Furthermore, if the difference between the last output data Lo and the data acquired by GPS G (Lo - G) exceeds 5 m or if the data acquisition time is not continuous, processing starts from “Start”.

Figure 4-1. GPS positional correction process flowchart (Patent pending)

Start

Number of jumps J=1 Average correction Δ=0 Corrected amount d=0 Compensated amount A=0 Compensated amount of second to last sample L” Compensated amount of last sample L’ L”=L’=GPS acquired data Minimum jump ε Maximum correction φ

G=GPS acquired data Uniformed speed assumed position L*=L’+(L’-L”)

Corrected amount L=G+A

Jump determination｜L-L*｜> ε

Reverse calculated compensated amount A=L*-GCalculated average compensation Δ=(JΔ+A)/(J+1)

Number of jumps update J=J+1

｜Δ-d｜> φ

d=Δ d=d+φ (Δ-d)/｜Δ-d｜

Output position data Lo=L-dUpdate to corrected value L”=L’ L’=L

Yes(Jump)

No(No jump)

Yes(Large correction)

No(Small correction)

Amount of correction determination

Poster PO-46

PO-46.9

The following formula is used to calculate and correct the current position from GPS data.

Output Lo (Current position) = GPS data G + Compensated amount A - Corrected amount δ

Figure 4-2. Example of GPS positional correction

Compensated amount, Average compensation, Corrected amount

-2 -1 01

234

567

89

1

0 5 1 1 2 2

Number of samples [L]

Latit

ude

and

long

itude

[m]

Compensatedamount A Average compensationΔ Corrected amount δ

GPS data, Corrected value, Output

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

0 5 1 1 2 2

Number of samples [L]

Latit

ude

and

long

itude

[m]

(True value)

GPS data

Corrected value L

Output Lo

Poster PO-46

PO-46.10

5-2 Azimuth Correction

The GPS used with Tanker Navi uses two antennas 50 cm apart and calculates the azimuth by triangulating the relative positions to a high degree of accuracy. In rare cases, the GPS outputs a completely erroneous azimuth due to clutter reflected from bridge wall, however Tanker Navi treats any azimuth whose change from previous one (measured every second) exceeds 3 degrees as an error and outputs the previous azimuth. If the change in azimuth is 3 degrees or less, Tanker Navi treats the GPS data as being normal and adopts it.

When approaching the berth, azimuth information can be obtained also by laser measurement via an approaching speed meter. The azimuth information from the approaching speed meter is deemed to be valid within 5 seconds after it was obtained, and while the information remains valid, the azimuth information obtained from the GPS is replaced by more accurate information obtained from the approaching speed meter. However, the azimuth information of the approaching speed meter can be completely wrong if the laser is reflected from a point other than flat body, therefore azimuth information obtained from the approaching speed meter is used only when it is within 3 degrees deviation of the azimuth information obtained by GPS.

6. MONITOR SCREEN DESIGN

To improve the operational safety of pilots, four screens are prepared for berthing (Fig. 5-1) and three are prepared for unberthing (Fig. 5-2) using ship support information (ship class, azimuth, position, course, etc.) presented by the national authorities. English is used so that foreign captains could understand.

a. Entering Hamadera Passage b. Approach [1]

c. Approach [2] d. Alongside Berth

Figure 5-1. Approach screens

Poster PO-46

PO-46.11

a. Departure b. Turning round

c. Exiting Hamadera Passage

Figure 5-2. Departure screens

Efforts were made in the following two ways. Firstly, average wind direction and significant wave height that are operational criteria for berthing at the Sakai LNG terminal berth -- were indicated with windsock and wave icons (Fig. 3) in addition to numerical figures. The icons turn red when exceeding operational criteria to draw pilots’ attention.

Secondly, the LNG tanker potion display interval was given ten levels: “Off”, “2 sec”, “4 sec”, “10 sec” ... “1 min”, “2 min” ... “10 min”. Pilots can choose the time interval of the mobile station freely.

• Average wind speed (7 levels): Operational standard … 8 m/sec or less

• Effective wave height (9 levels): Operational standard … 1 m or less

Figure 5-3. Windsock and wave icons used for average wind direction and effective wave height

less than 1m/s

lessthan2m/s

less than 4m/s

lessthan6m/s

lessthan8m/s

less than

10m/s

more than

10m/s

less than 0.1m

less than 0.2m

less than 0.4m

lessthan0.6m

lessthan0.8m

lessthan1.0m

lessthan1.2m

less than 1.4m

morethan1.4m

Poster PO-46

PO-46.12

7. CARRYING ONBOARD, TAKEDOWN AND SETUP

When installing Tanker Navi to an LNG tanker, Staff of Sakai LNG brings it to the Osaka Tugboat Operators Association the day before arrival of the LNG tanker. And then Tanker Navi is carried to the LNG tanker by tugboat before the pilot comes onboard.

After the LNG tanker crew lifts Tanker Navi onboard by the ropes, it is carried to the bridge wing where it is installed and the computer is powered up and handed over to the pilot.

Uninstallation is done in the opposite order in which Tanker Navi is installed onboard. Once the LNG tanker has been unberthed, turned around and entered the shipping lane, Tanker Navi is packed in its trunk and lifted down to the tugboat by the tanker crew. The tugboat brings it back to the Osaka Tugboat Operators Association and Sakai LNG comes to get it.

To set up Tanker Navi, the GPS antenna kit and pilot monitor are taken from the trunk and the GPS antenna kit is installed in a predetermined point on the port-side bridge wing wall. The pilot then powers up the computer inside the trunk and the pilot monitor around his neck.

Figure 6. Tanker Navi as set up

8. MAJOR TROUBLES AND THEIR IMPROVEMENT PROCESSES

We have experienced and overcame various troubles in the development process and at an early stage of practical use of Tanker Navi. We would like to introduce several examples of the troubles and their improvement approaches as follows;.

GPS antenna kit

Poster PO-46

PO-46.13

(1) Wrongly Selected GPS Antenna.

• Trouble

When the first LNG tanker (DWIPUTRA) entered and left port, the ship’s profile was displayed in a different direction from the actual ship (Fig. 7-1).

Figure 7-1. Wrongly indicated LNG tanker profile

• Improvement Approach

The original GPS antenna employed a magnetic compass, and Tanker Navi displayed the LNG tanker’s profile based on the azimuth obtained by this compass.

At an early stage of development of Tanker Navi, we have conducted a test on an LNG tanker in dry dock to check the performance of magnetic compass GPS antenna. We have confirmed that, though it was slightly affected by the steel plate of the tanker’s body, it functioned without a problem when used 50 cm apart from the steel plate. Based on the result of the test, we decided to use the GPS antenna approximately 150 cm apart from the wing deck of the LNG tanker.

However, as the design of the first LNG tanker was different from the tanker on which we have conducted the pre-use test of the GPS antenna during its dry dock, it was confirmed that, as a result of check test conducted while the tanker was berthed, the steel plate of the tanker body destabilized the compass reading unexpectedly. (It was confirmed that the compass reading changed according to the location on the bridge wing and the height of the GPS antenna.)

Based on the result of investigations, we decided to use two GPS antenna and calculate the azimuth in place of original magnetic compass. (Fig. 7-2).

Poster PO-46

PO-46.14

Figure 7-2. Old and new GPS antennas

(2) GPS Antenna Location.

• Trouble

The ships’ direction displayed on the monitor suddenly changed to a wrong direction. The situation of the wrongly indicated course of the LNG tanker is shown in Fig. 7-3.

Figure 7-3. Wrongly indicated course of LNG tanker

• Improvement Approaches

The GPS antennas had been located on the steel deck of the bridge wing near the bridge, but the position information obtained from the GPS satellite was reflected from the bridge wall and wing wall before being received by the GPS antenna, which resulted in the displayed direction being different from the actual direction.

As a countermeasure, the antenna kit was located on the top of the wing wall as far from the bridge as possible to prevent it from receiving signal reflected from off the wing wall, etc (Fig. 7-4).

Magnetic compass

GPS compass

Poster PO-46

PO-46.15

Figure 7-4. Old and new GPS antenna locations

(3) Ship-to-Shore Communications.

• Trouble

Originally, only cell phones were used for ship-to-shore communications, but often the connection could not be made or the call was cut because of poor radio wave conditions. The base station could not confirm the LNG tanker position information and the mobile station could not confirm the weather information at Sakai LNG berth and/or approaching speed information.

• Improvement Approaches

We have tested several ship-shore communication methods for Tanker Navi including cell phones (by DoCoMo and au), commercial wireless, MCA, wireless LAN and satellite phones, and adopted cell phone (by au) which demonstrated the best results. However, connections in actual use were unstable and approaching speed which is one of the most important information in berthing operation could not be confirmed, therefore we decided to use a wireless LAN for short-distance communications. The rated transmission distance of a wireless LAN is about 200 m, however, actual transmission distance reaches up to 3,000 m (if the weather condition is good), and we decided to use a wire-less LAN in combination with cell phone.

9. ACKNOWLEDGEMENTS

In developing Tanker Navi system, Sakai LNG played the leading role and did the studies, planning and basic design, and Kyodo Jyushin Service Co., Ltd. (KJS) subcontracted the detailed design and manufacture.

The biggest contributor to the completion of this system was the Hanshin Pilot Union. In particular, the opinion of pilots on actual use was crucial in designing the pilot monitor. The design of the pilot monitor has been decided through a number of consultations with pilots such as whether to use north up or head up, how to display the text and layouts. As soon as a prototype was ready, demonstration and presentation session on how to use Tanker Navi was held on a small boat for all pilots of the Hanshin Pilot Union. After extensive follow-up, Tanker Navi has finally been completed.

GPS antenna kit

Poster PO-46

PO-46.16

The authors would like to express their sincere appreciation to former President Tanaka, current President Kodama and others of the Hanshin Pilot Union.

The two and a half years of development required an investment of about $300,000. Since Sakai LNG is in the business of unloading, storing, vaporizing and supplying LNG, it has no intention of selling this system, but interested persons should contact Japan Marine Science, Inc. who is acting as the sales representative of KJS.