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1 INTRODUCTION
Indonesian fisherman small fishing boats type
jukung/cadik or outrigger) are popular in Figure 1. It
was built by wooden boat craftsmen, especially along
the northern coast of Java. However, they are
currently experiencing difficulties in wood materials,
especially teak (Imron et al., 2020). In addition, the
price of this wood is always increasing every year.
The price for per m3 of wood with a length of 3
meters of wood the price reaches IDR 13 million
(equal to 900 USD). A wooden ship with a length of
less than 12 meters requires wood from 0.8 to 1.6 (m3)
for the hull only with a thickness of 3 cm. Wooden
boats can be used for 10 years, and after that it
requires quite expensive maintenance and repairs.
Wooden boat craftsmen try to make wooden boats
more durable by coating them with fiberglass with a
thickness of more than 5 mm, and this has led to an
extraordinary increase in the price of the ship.
Fishermen really need a fishing-boat that is strong
and cheap, so it is necessary to look for alternative
materials to replace wood in the construction of small
boats (jukung/cadik), but fishing boats must be
seaworthy in accordance with special vessel
regulations under 24 meters in length, to ensure the
safety of fishermen while at sea. One of the materials
that can be used is from HDPE blue drum scrap
(fig.2). The hull of an jukung/cadik boat made of
finished wood per square meter price USD 15.00/m2,
and from HDPE blue drum scrap, the price per square
meter of material is USD 8.57/m2.
The potential for making alternative materials in
the form of natural fiber composites such as bamboo
and rattan and other materials has been widely
Mechanical Properties of Small Boat Construction from
HDPE Blue Drum Scrap
M. Ridwan
1
, Sulaiman
1
, S. Sugeng
1
, Sarwoko
1
& H. Nies
2
1
Diponegoro University, Semarang, Indonesia
2
SLV Mannheim GmbH, Mannheim, Germany
ABSTRACT: This paper discusses the mechanical properties of alternative wood substitute materials in the
construction of small boats (jukung/cadik type). Jukung/cadik boat as a small fishing boat with a length overall
6,400 m, design beam 1,530 m, design draft 0.380 m, displacement 2,442 tons, wetted surface area 15.58 m2, the
pressure acting on the submerged hull needed minimum material used has a strength of 0.0039 MPa or 3.92
kN/m2. The replacement material used is the HDPE blue drum scrap, which has an average thickness of 3mm,
then made into two layers as laminate. The laminate process uses welding. The results of HDPE laminate
material from these two layers are tested for tensile and compressive strength to meet the material strength
requirements for small ship hulls. They were testing the strength of HDPE welded joints with type A1
specimens. Tension and compression of the two-layer laminate material was tested with specimens of type A2,
A3, and A4. The tensile test results for A1 specimens obtained for welding tests are pretty good at 17.1 MPa,
then the results of compression tests for specimen type A2, A3, and A4 on average are 23.36 MPa, which is
greater than the need for the strength of the jukung/cadik hull.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 16
Number 3
September 2022
DOI: 10.12716/1001.16.03.20
574
practiced, such as bamboo composites with HDPE or
polyethylene (PE) and polypropylene (PP) plastics
which are commonly used thermoplastics, due to
price and processing temperature relatively low
(Shah, 2020; Liu, et al., 2009; Yao et al., 2018). HDPE
material has the morphological properties of MFR
(190oC/2.16 kg) = 6.1 g/10 min, density = 0.952 g/cm3.
Indonesia produces plastic waste, especially HDPE
blue drum scrap (a container for raw materials for
chemical industry products or similar industries) per
month, reaching 1.4 billion kg (equivalent to 5.6
million drums with a capacity of 200 liters); the total
number in 2018 was 12.2 billion kg or equivalent to
48.9 million HDPE blue drum scrap (BPS 2019). High
density polyethylene (HDPE) is a thermoplastic
polyethylene, made from petroleum. HDPE is
recyclable, and has number 2 on the symbol for
recycling, is safe and has a lower risk for health and
the environment (American Chemistry Council and
Association of Plastic Recyclers, 2017; ISO, 2012;
ASTM, 1993).
The process of utilizing HDPE blue drum scrap as
a material for making jukung/cadik is very simple,
namely making it a laminate material by a welding
process using a thermoplastic welding machine.
HDPE blue drum scrap formed into sheets with an
average thickness of 3mm, then laminated from two
layers, which are welded at a distance of 3cm and
then pressed so that a laminated HDPE sheet is new
material. Then this material is subjected to a tensile
test, a flexural test, so that its mechanical properties
can be known and used as a small hull construction
(Badache et al., 2018).
2 VESSEL AND DESIGN CONSIDERATIONS
Jukung/cadik boat as a small fishing-boat with a
length overall 6.4 m, design beam 1.53 m, design draft
0.38 m, displacement 2.442 tons (2,442 kg), wetted
surface area 15.58 m2, the pressure acting on the hull
submerged in water is nominally 1.5674 kN/m2
(0.0015674 MPa), with a safety factor of 2,5 times, the
minimum material used has a strength of 0.0039 MPa
or 3.92 kN/m2.
Small boat dimensions: 8.00 m long/length overall,
1.69 m wide and 0.50 m laden, 3.175 ton- displacement
and 12.70 m2 underwater surface areas. Requires
minimum hull strength of 2.50 kN/m2 or the
equivalent of 0.0025 MPa, with a safety factor of 2,5
times, the minimum material used has a strength of
0.00625 MPa or 6.25 kN/m2.
Jukung is made in various sizes, the long ones are
usually for transportation, and the short and wide
ones are for catching fish. This small Jukung or boat
was initially made from a carved piece of wood that is
quite long. Manufacturing in this way wastes a lot of
raw materials that are then made from thick
boards/wood. Jukung, in addition to catching fish,
and means of transportation in rivers and lakes, is
also used as a place to sell floating in the Kalimantan
river area. The Demak area has 3,872 boats, such as
jukung.
The continuous use of wood for the manufacture
of jukung as small boats will reduce the availability of
wood in nature, disrupting the natural balance. It is
the reason for the need for replacement materials that
are more durable and can be recycled. One of the
materials that can be utilized is HDPE blue drum
scrap.
Figure 1.a. Demak Jukung Boat (BanGhoL)
Figure.1.b. Common form of jukung/cadik
(https://infopublik.id/galeri/foto/detail/88083)
3 MATERIAL
The material used is from HDPE sheets which come
from HDPE blue drum scrap. This HDPE has material
properties: Density 940 kg/m3, Melting Point 130.8° C,
crystallization temperature 111.9°C, enthalpy of
fusion 178.6 kJ/kg, Thermal conductivity 0.44 W/m.°C,
specific heat of solids 1.9 kJ/kg.°C, crystallinity 60%
(Thakare et al., 2015). The welding wire material is
High-Density Polyethylene (HDPE) Plastic Welding
Rod, 4mm or 1/8 "in diameter.
Table 1. HDPE Material Properties
_______________________________________________
Density 940 kg/m3
Melting Point 130.8° C
Crystallization Temperature 111.9°C
Enthalpy of fusion 178.6 kJ/kg
Thermal conductivity 0.44 W/m.°C
Specific heat of solids 1.9 kJ/kg
crystallinity 60%
_______________________________________________
Source: Thakare et al., 2015
The HDPE welding process is required to make
two sheets of HDPE plate obtained from HDPE blue
drum scrap (Figure 2a). We cut the drum at the top
and bottom and take the middle part in the form of a
sheet, and then welding is carried out to form one
material from the two thin sheets (Figure 2b).
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(a)HDPE blue drum scarp (b) Joining two layers of HDPE
sheet by welding
Figure 2. Joining two layers of HDPE sheet by HDPE
welding
The welding strategy used is a straight-line pattern
with a welding period of 3 cm, with the pattern being
shown in Fig.3.
Figure 3. Welding pattern in HDPE sheet Elimination
Figure 4. Joining two layers of HDPE sheet by HDPE
welding
4 EXPERIMENTS
4.1 Preparation
HDPE sheets are prepared from used barrels and
cleaned of adhering chemicals. The sheet consists of
two parts with a thickness of 3 mm. To get the
material from these two layers is done by welding as
shown in Figure 4, then welding is carried out
according to the pattern according to Figure 5.
Figure 5. Welding pattern in HDPE sheet elimination
The next process is to consider the quality of the
interlaminar, by showing the cross section. This
process takes into account the waterproof properties
of the resulting material. Figure 6 showed the result of
the material from the union of two HDPE blue drum
scrap sheets.
4.2 Welding machine
The welding process is carried out using an HDPE hot
air welder with a filler of the same material. This tool
can melt filler from 30oC to 680oC, power supply
consumption: AC-220V 50 Hz, Heat power: 1600W,
Air mass flow max 230 liters per minute.
Figure 6. Welding gun HDPE.
Figure 7. The cross-sections of material from 2 layers and
watertight
This HDPE material is considered to be suitable for
small ship hulls. Joints are considered by ensuring the
strength of the welded joints we test. In addition, A1
is the name of sample in this study, with the amounts
used being 112 pieces, A2 is the name of for samples
of two layers of laminate as many as 128 pieces, A3 is
for samples of two layers of laminate with cross-
welding, and A4 is for samples of two layers of HDPE
sheets.
4.3 Testing machines
The test tool used is a mechanical test device based on
ASTM D638 and ISO 527-1, the magnitude of the force
applied, F = EA v/(60L) ... (ISO 527-1), is directly
proportional to the modulus (MPa), the cross-
sectional area (mm2), and test speed (mm/min), and
inversely proportional to the clamping distance (mm),
and maximum capacity 10 kN
4.4 Specimen production
The first thing that needs to be tested is the strength of
HDPE welding results to provide confidence in the
strength of the connection of the material by the
welding method., for that, it is necessary to weld and
form a test object that is labeled with type A1, as
shown in the picture.9. The dimensions of the test
specimens type A1 are based on ASTM D 638, 165 mm
long, and 19 mm wide (Khalaf, 2015; Bledzki et al.,
2007).
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The new laminated material is made from two
layers of HDPE blue drum scrap sheet, as shown in
Fig.8. Then these specimens are labeled type A2, A3,
and A4. Type A2 welding direction is longitudinal in
the tensile test, type A3 and A4 are transverse
direction welding. Type A3 is tested for tension. Then
type A4 is tested for pressure (bending test).
Figure 8. Laminate material
Figure 9. Laminate specimens with different welding
directions.
5 RESULTS
5.1 Specimen type A1 Test
HDPE welding joints with a V seam pattern (single V
butt joint) and an average material thickness of
3.035mm, produce an average tensile strength of
1011.94 N with a cross-sectional area of 58.79 mm2 or
17.21 MPa (Figure 7).
Figure 10. Results of the T-1 tension test (A1)
Tests also need to be performed to show possible
failure modes and failure surfaces. The tensile test
results are shown in Figure 11 and Figure 12. The
results for each test are conducted, so that the
standard deviation/spread in the results can be
considered.
Figure 11. A1 sample making
Figure 12. (a) Tensile test sample; (b) tensile test results
Moreover, Sample type A1 as many as 112 pieces is
used to conduct a test for HDPE welded joints to
show the frequency of the tensile test results (Figure
10). The test results show an average tensile strength
of 1011,939 Newton, with a standard deviation of
0.069 and stress of 17.11 MPa, with a standard
deviation of 0.062 approaching the test results without
welding (the original material) for comparison is
1012.00 Newton and stress of 17.21 MPa.
5.2 Specimen type A2 Test
Tensile strength for two layers of laminate with
longitudinal welding (A2), obtained an average
thickness of 6.59 mm resulting in an average tensile
strength of 2225.48 Newton, with standard deviation
0.74 with a cross-sectional area of 124.28 mm2 and
average stress 17.9 MPa (Figure 13).
Figure 13. Results of the T-1 tension test (A2)
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Figure 14. Testing process of The number of
samples tested for type A2 (two layers of laminate) as
many as 128 pieces.
Figure 14. A2 Testing.
5.3 Specimen type A3 Test
Tensile strength for two layers of laminate with cross-
welding (type A3) as in figure 9.a. on, obtained an
average thickness of 7.42 mm resulting in an average
tensile strength of 2324.26 N with a cross-sectional
area of 140.31 mm2 or 16.45 MPa.
5.4 Specimen type A4 Test
The bending test results from two layers of HDPE
sheets (type A4) have average load 104.39 Newton
dan yielded an average bending stress of 23.37 MPa
and the modulus of elasticity was 692.70 MPa (Figure
15; Figure 16).
Figure 15. Bending Test
Figure 16. Bending test results (A4).
6 DISCUSSION
The difficulty in this experiment is in making the
same specimen. It may be because the tools used are
manual and still rely on human hand skills to make
the test specimen object.
Welding strength is almost equal to the strength of
the material when tested in tension, namely the
average tensile strength of 1011,939 Newton. At the
same time, the original material is 1012.00 Newton,
and this connection strength convinces us to make a
new material using the laminate method through
welding treatment horizontally with a regular pattern
following the pattern in Fig. 5 above.
The new material, formed from two layers of
HDPE blue drum scrap with a longitudinal weld
pattern, has a tensile strength of 2225.48 Newton and
2324.26 N with transverse welded polo. The average
compressive strength is 104.39 Newtons, and the
modulus of elasticity is 1301.40 MPa, which is far
above the nominal strength required by the hull of a
Jukung/small ship, which is only 0.0039 MPa.
On this occasion, this laminated material is applied
to replace wood for the Jukung's hull. The next stage
will be tested for the strength of the connection
between the construction components, such as the
hull and floor or frame and other parts. The effect of
machine vibration on the strength of the construction
joints will also be developed.
The application in Jukung can be seen in Fig. 17
below, which is the middle hull of the jukung with
HDPE blue drum stamp laminated material.
Figure 17. The middle of Junkung's hull.
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7 CONCLUSIONS AND RECOMMENDATIONS
The results of the tensile and bending test for welding
joints in the manufacture of HDPE sheet construction
using the welding method and with lamination
(sandwich), where there is an average tensile strength
of 1011,939 N (Newton) or 17.21 MPa) for the welded
joints. The result of the tensile test of the two-layer
laminate construction obtained that the average
tensile strength was 2225.48 N or equal to 17.9 MPa.
The flexural test result of two-layer welded joints with
an average of 23.37 MPa is much higher than the
minimum requirement for small hull strength (0.0039
MPa) and the modulus of elasticity is 692.70 MPa.
The next step is how to apply it in the field of the
making process of small ships using appropriate
technology at a very low price by comparing it with
wood materials which has expensive price. As for
comparison, the hull of an outrigger/jukung/cadik
boat made of finished wood per square meter price
from USD 15/m2 to USD 30/m2, and from HDPE blue
drum scrap, the price per square meter of material is
USD 8.57/m2. So, by considering the low cost of
HDPE material, it is possible to produce this material
in low-tech environment. This makes it a suitable
alternative to teak wood in the manufacture of
outriggers at low cost, considering that most of the
users are small-scale fishermen.
ACKNOWLEDGMENT
The author would like to thank the Director of the
Schweißtechnische Lehr-und Versuchsanstalt Mannheim
GmbH, Germany, as a form of collaboration in this research.
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