Page 56 - Practical Design Ships and Floating Structures

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2.1 Material Cost

Material cost of a ship occupies a big amount and reaches to 50-60 % of the total building cost, as
shown in Table 1. Among material costs, steel cost is the biggest one and occupies 35 %. For example,
in a VLCC with double hull, thirty and some thousand tons of steel is used and 30-80 % of them is
higher tensile strength steel.

The cost of main engine occupies about 15 % and those of other outfitting occupy about 50 %.
2.2 Fabrication Cost

Fabrication cost occupies more than 30 %. Among them hull structural part occupies about 50 % and
outfitting part occupies about 15 YO, depending on the features of ships.

2.3 Design Cost

It is said the ratio of design cost against the building cost of a ship is about 5 %. Design, although a
simple word, continues from basic design through yard plans in shipyard, so it is a long duration
before the completion. Design of ship is divided into two stages, basic design and detail design. It
takes 2-3 months for basic design 6-8 months for detail design. Consequently design duration and
costs vary in accordance with the features of ships.
2.3. I Basic design

After the building contract is signed the basic characteristics of the ships are decided by basic design to
satisfy the specifications attached to the contracts. Basic design consists of total design, hull structural
design, outfitting design(hul1 part and machinery part) and electric design. The basic design cost is less
than 10% of the total design cost. However by this basic design, 90 % of the total building costs of a
ship is decided, so it is the most important division.

2.3.2 Detail design
This is the design for the actual building of ships and divided into functional design and fabrication
design. Number of design plans of detail design exceeds some ten thousands sheets. The costs of
detail design occupy 90 % of total design costs.
2.4 Influence of Application Ra& of Higher Tensile Strength Steel

The application &Q of higher tensile strength steel is between 30- 80 % of total structural steel,
depending on the requirements of ship owners. Figure 1 shows the results of the cost study on the
application ratio.
(1) By increase of the application of higher tensile strength steel from 23 % to 80 %, total steel
weight decreases by about 6 % and material cost decreases by about 1 %.
(2) Fabrication cost decreases by about 1 % due to the change of the welding metal volumes and the
reduction of the plate thickness.
(3) Design cost is not influenced by the application &of higher tensile strength steel.
(4) Finally the cost reduction by the application of higher tensile strength steel is about 1 YO.