Mitsubishi Heavy Industries Technical Review Vol. 52 No. 1 (March 2015)47

New Generation LNG Carrier "SAYAENDO"

Nagasaki Ship & Ocean Engineering
Department, Shipbuilding & OceanDevelopment Division
C o m m e r c i a l Av i a t i o n & Tr a n s p o r t a t i o nSystems

In recent years, there has been increasing demand for LNG (liquid natural gas), as well as
LNG carriers, both domestically and internationally, with environmental considerations and theshale gas revolution in the U.S. in the background. Mitsubishi Heavy Industries, Ltd. (MHI) has
developed Sayaendo, a new generation LNG carrier, and is now receiving orders for its
construction. In the midst of this, LNG VENUS, an LNG carrier for Osaka Gas Co., Ltd. andMitsui O.S.K. Lines, Ltd., which was the first Sayaendo ordered, was completed. This paper
presents an overview of Sayaendo together with its features.

|1. Overview of Sayaendo
Sayaendo is a 155000m3 MOSS type (spherical tank type) LNG carrier. In contrast toconventional MOSS carriers, the spherical cargo tanks of which are blanketed with separate
hemispheric tank covers, Sayaendo has a continuous tank cover that covers the cargo tanks. Thenickname Sayaendo comes from its exterior. This carrier, with a continuous cover and sphericaltanks contained thereunder, looks like peas in a pod, known as sayaendo in Japanese.
The adoption of a continuous cover integrated with the hull reduces the weight of Sayaendo
while ensuring overall structural strength. It also significantly mitigates wind pressure from thefront, which becomes resistance to propulsion. The MHI Ultra Steam Turbine Plant (UST), which
has higher thermal efficiency due to the reheating cycle, is used for the main propulsion plant. This
plant, together with the effect of the continuous cover, contributes to the significant improvementof the fuel economy performance. In addition to the reduction of CO2 emissions resulting from theimprovement of fuel efficiency, Sayaendo has superb environmental friendliness, including being
capable of 100% gas-fired operation for all operational areas and the reduction of surplus gas
treatment amount due to the adoption of low boil off rate (BOR: index of gas amount generated by
the introduction of heat) heat insulation.

|2. Features of Sayaendo
The features of Sayaendo are described below.

2.1

Reduction of hull weight

Conventional MOSS type LNG carriers have separate hemispheric steel tank covers foraluminum spherical cargo tanks. In this case, the covers are additional components, and thestructural strength is principally ensured by the main hull excluding the covers. Sayaendo has acontinuous tank cover that covers four spherical tanks and which is integrated with the hull,contributing to the strength. As a result, both the improvement of overall strength and a drop in thehull weight due to the reduction of additional components are attained.

2.2

Improving transportation efficiency and securing operational versatility

Through the adoption of stretch tanks, which are extended upward with the same diameter as
the spherical tank, Sayaendo attains an additional cargo capacity of 8000m3 compared with MHI’sconventional 147000m3 carrier capacity with the beam unchanged, resulting in the improvement ofMitsubishi Heavy Industries Technical Review Vol. 52 No. 1 (March 2015)
48

transportation efficiency.
Sayaendo has good compatibility with LNG terminals all over the world in consideration ofuse for various LNG trades. For this purpose, main dimensions that are approximately the same as
MHI’s conventional 147000m3 carrier capacity are kept unchanged through the adoption of thecontinuous cover and the stretch tanks. Sayaendo also has main dimensions within the maximum
shape (366m in length over all, 49m in width, and 15.2m of draft) for passing through the New
Panama Canal, and therefore its operational versatility is high.

2.3Improvement in maintainability

The adoption of the continuous tank cover allows for the simplification of a conventional
MOSS carrier’s complex structure above the tank cover that supports pipes, wires and pathways,resulting in a significant improvement in maintainability.

2.4

Improvement of fuel economy performance

Sayaendo is applied a newly developed optimal hull form that takes advantage of a reductionin the hull weight to enhance propulsion performance. In addition, the adoption of the continuoustank cover has reduced wind resistance while cruising. Furthermore, the UST is used as the main
propulsion plant, resulting in an approximately 15% improvement in efficiency with the advantageof the conventional turbine plant unchanged.

2.5

Environmental considerationIn addition to the factors for improving fuel consumption described in 2.4, further
improvement of propulsion performance using additional energy saving devices can reduce CO2
per unit load in actual operation by up to approximately 25% in comparison with the conventional
147000m3 MOSS carrier. Sayaendo also has environmentally-friendly specifications such as thereduction of NOx emissions using the UST, the capability of 100% gas-fired operation for all
operations including while in-port, a decrease in the amount of surplus gas treatment due to theadoption of low BOR heat insulation, and the mitigation of the influence on marine ecosystems
through the use of a ballast water treatment system.

|3. LNG VENUS
LNG VENUS is the first of two of the same type of LNG carrier built for Osaka Gas Co.,
Ltd. and Mitsui O.S.K. Lines, Ltd., which were the first Sayaendo orders MHI received in October
2011. LNG VENUS was delivered in November 2014 after the verification of the design
performance through a sea trial and a gas test in October 2014. Table 1 shows the principal
particulars and Figure 1 shows the overall layout.
Table 1 Principal particulars of LNG VENUS
LNG tank type
Cargo tank capacity(m3)(100% full, -163°C, atmospheric pressure,excluding dome space)Nationality of ship
Classification
Length, between perpendiculars(m)Breadth, moulded(m)
Depth, moulded(m)Designed draught, moulded(m)International gross tonnage
Service speed(kt)
Main propulsion plant

MOSS type spherical tank (four tanks)
155,691
Japan
NK (Nippon Kaiji Kyokai)
288.0
48.94
26.0
11.55
13671019.5
Reheating marine steam turbine plant(MHI Ultra Steam Turbine plant)

The inside of the continuous tank cover is separated into four hold spaces. The cargo
manifold for connection to ground terminals when loading and unloading is located between theNo. 2 and No. 3 cargo tanks. There is a cargo machinery room at the top of the tank cover between
the No. 3 and No. 4 cargo tanks.
This carrier is equipped with a reaction fin and a twist rudder with a bulb as additionalenergy saving devices for the improvement of propulsion performance. In addition, due to theadoption of a heat insulation system with a BOR of 0.08% per day, a significant reduction inMitsubishi Heavy Industries Technical Review Vol. 52 No. 1 (March 2015)49

comparison with conventional carriers, economical operation can be performed at wide range ofspeeds. Furthermore, a rudder that can be steered up to 45 degrees during low-speed cruising, thebow thruster, and the helicopter deck improve in-port controllability and operability.

Figure 1

Overall layout|4. Future prospects
The high energy-saving performance and environmental friendliness of Sayaendo LNG
carriers including LNG VENUS are attracting great interest from the shipping industry. MHI has
been successfully receiving orders and building Sayaendo, which is one of the leading eco-ship
products being actively developed in the Japanese shipbuilding industry. At MHI, eco-ship
products including Sayaendo are positioned as added-value core products that the Ship and Ocean
businesses focus on. MHI will continue to promote further technological development and theextension of the lineup, including the development of a new carrier to take advantage of shale gas
opportunities in North America.