Surfboard Project Part 2
by
Marie Joo Le Guen
and
Roger H Newman
26 June 2008
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The opinions provided in the Report have been provided in good faith and on the basis
that every endeavour has been made to be accurate and not misleading and to exercise
reasonable care, skill and judgment in providing such opinions. Neither Scion nor any of
its employees, contractors, agents or other persons acting on its behalf or under its
control accept any responsibility or liability in respect of any opinion provided in this
Report By Scion.
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SURFBOARD PROJECT PART 2
ABSTRACT
Two full-scale surfboards were constructed by replacing the conventional glass-fibre
reinforcement by harakeke and/or ramie fibres. Both surfboards were constructed
around a conventional polyurethane foam core, and the fibres were contained in a
conventional unsaturated polyester resin. Surfboard 2 was reinforced with ramie plainweave fabric mats. Two mats were used, a green tie-dyed mat on the deck and a
bleached mat on the keel. Surfboard 3 was also reinforced with ramie plain-weave fabric
on deck and keel, and a red harakeke wet-laid mat was added on the deck for
decorative purpose. For both boards, the white colour of the keel was enhanced by
mixing white pigment with the resin. Both surfboards were tested in surf, without
obvious damage except for a shallow dent in Surfboard 2. Fabric is better than wet-laid
reinforcement, in terms of high performance surfing, but wet-laid reinforcement offers
decorative effects and a combination of fabric and wet-laid fibre shows potential.
1. INTRODUCTION
Background
FRST contract BPLY0402 included Objective 1: “Natural Fibre Networks and their
Composites”. Milestone 9 (Prototype Trials) specified: “Complete prototype trials with
industry partner(s) for a concept or target product or intermediate product based on
natural fibres or a natural fibre network.” Such prototypes included glass-free
surfboards, fabricated and tested in a project that involved Sunshine Design and Surf,
Mt Manganui.
Surfboard 1 was reinforced with mats of harakeke wet-laid fibre, and described in an
earlier report (Le Guen 2007). Testing in the surf showed some weaknesses, especially
in impact strength, and examples of damage were recorded (Le Guen 2007). Surfboard
2 and 3 were designed to assess ideas for improving the mechanical properties.
Discussions with the surfboard shaper (Mike Murden, Sunshine Design and Surf)
identified two specific problems encountered in construction of Surfboard 1.
(1)
The harakeke reinforcing mats soaked up resin. Since the mats had a weight of
just 40 g m-2, this meant that the weight of harakeke reinforcement was just one
third of the weight of a conventional “4-ounce” glass fabric. Surfboard 1 was
therefore fragile relative to a conventional design.
(2)
The harakeke reinforcing mats showed poor drapeability and permeability, so
resin became trapped in an uneven manner. Subsequent shaping removed fibre
from the high points, leaving resin that was poorly reinforced. The tight curves of
the rails were particularly fragile.
A review of fibre-network compaction has shown that woven reinforcement can be
compacted to approximately three times the volume fraction of non-woven
reinforcement (Toll 1998). In other words, we should be able to treble the volume of
plant-fibre reinforcement simply by switching from non-woven to plain-woven
reinforcement. Hemp fabric is commonly used in surfboards, e.g. by Sustainable
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Composites Ltd (www.suscomp.com). Our experience with plain-weave linen
suggested that moisture uptake might cause problems (Burns and Newman 2006). We
tried to avoid those problems by selecting a reinforcing fibre with an exceptionally low
content of non-cellulosic matter, i.e., plain-weave ramie fabric (Newman and Le Guen
2008).
2. EXPERIMENTAL
2.1 Surfboard 2
The ramie fabric was imported from China under the name Dazhu Golden Bridge ramie
fabric. More details are provided elsewhere (Newman and Le Guen 2008). The
grammage was approximately 125 g m-2. Four mats were cut into rectangles
approximately 2 m by 1 m. One was tie-dyed for the deck.
2.1.1 Tie-dyeing process
Two small samples were dyed in preliminary experiments, in to get the concentration of
the dye and the design right. The dye used was a commercial cloth dye; Dylon 59
Green verdure, purchased in Spotlight.
Sample 1: 7 g of fabric was tied with 6 knots and immersed in 300 ml of warm water
with 7 g of salt and 2.8 g of dye (Figure 1).
Sample 2: 7 g of fabric was tied with 4 knots and immersed in 300 ml of warm water
with 7 g of salt and 1.4 g of dye (Figure 2).
Figure 1: Sample 1
Figure 2: Sample 2
From a design point of view, the conditions for preparing Sample 1 seemed preferable,
so they were selected for the full-size mat.
Eight rubber bands were attached to the full size mat (2 m by 1 m) representing 191 g of
fabric. The mat was immersed for 2 h in 4.5 L of warm water in a bucket with 76.4 g of
dye and 191 g of table salt. It was then rinsed with water until there was no dye bleeding
out the fabric. The mat was then ironed (Figure 3).
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Figure 3: Tie-dyed ramie fabric mat
2.1.2 Bleaching process
To accentuate the white colour of the other three mats, they were bleached with
commercial bleach powder. The bleach used was NapiSan® OxyAction® made and
distributed by Reckitt Benckiser and purchased in Countdown Rotorua.
The three mats were bleached at the same time in a 10 L solution at 200 g L-1 of bleach.
They were left 48h then rinsed and ironed.
The four mats were then sent by courier to Mike Murden (Mount Maunganui) to be used
in shaping Surfboard 2.
2.1.3 Characteristics of Surfboard 2
The shaper used 2 plies, one tie-dyed mat on the deck and one white mat on the keel.
The bleaching process of the mat was not enough to get a pure white colour, so white
pigment was added to the resin on the bottom part. The shaper experienced difficulty in
wrapping the fabric around the tight curvature of the rails, and used grey tape to hide
the defects.
The mass of Surfboard 2 was 3305 g without fins. This surfboard was sufficiently light to
be recognised as a high-performance board.
Surfboard 2 was tested for a first immersion in the Blue Lake over a period of less than
one hour, and in the waves in Mount Maunganui as a kite-surf board (Figure 4). No
obvious damage was recorded, apart from a shallow dent attributed to pressure applied
by a heel on the deck. It was used again in confused surf after a storm at Riversdale
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Beach, with no further visible damage. Although the initial intention was to test this
board to destruction, the weather patterns over the summer of 2007-2008 meant that
most of the scheduled tests were cancelled.
Figure 4: Damien Even kite
surfing on surfboard 2
2.2 Surfboard 3
Surfboard 3 was built with a hybrid reinforcement combining the decorative design of a
harakeke reinforcing mat and the strong mechanical properties of plain-weave ramie
fabric.
Harakeke line fibre was obtained from the Templeton Flax Mill via AgResearch. One
kilogram of raw fibres was chopped in 2.5 cm in length with scissors and then soaked in
water one overnight. The pulp used in Surfboard 1 showed an abundance of coarse
fibres which were partly removed by hand. To avoid this work, the fibres for Surfboard 3
were pulped at the same temperature but at higher sodium hydroxide concentration (45
g L-1) and over a longer time.
The raw fibres were drained but the water uptake was measured and allowed for in
making up the pulping liquor. The liquor-to-fibre ratio was 16:1, with a NaOH charge of
36% of the oven-dried weight of harakeke fibres. Anthroquinone was added at 0.18% of
the weight of harakeke fibres. The temperature was raised to 140 ºC over 90 minutes
and held for a cooking time of 180 minutes. The pulp was cooled and washed with
water, then kept wet at 4 °C in plastic bags into the PAPRO fridge to avoid fungal
growth.
To obtain a good quality pulp, the pulped fibres were beaten in the 3 L egg beater by
100 g portion into 500 mL of water for a period of 10 min at high speed (speed 10). As
expected, the proportion of coarse fibres was smaller than in the case of Surfboard 1. .
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Production of each mat used 540 g of wet fibres which corresponded to a grammage of
the air-dry mats of approximately 65 g m-2. Two bags of pulp, each containing 540 g,
were dyed with a cloth dye “DYLON 36 Cherry Red”. Each bag of fibre was dissolved in
10 L of warm water (50 °C) with 500 g of table salt and 100 g of dye. During the first 15
minutes, the fibres were stirred and then left during 45 additional minutes. The pulp was
washed with cold water until the water flowed colourless.
2.2.1 Wet laying
The two harakeke reinforcing mats were made with the same equipment and the same
procedure as the mats for Surfboard 1, except for weather conditions. Surfboard 1 was
made in summer time, allowing the mat to dry quickly unlike Surfboard 3 which was
made at the beginning of winter in cold conditions (Figure 5). Once made, the mats
were air dried and ironed flat. The best-looking one was cut to a rectangle 2 m by 0.65
m and hot pressed at 50 °C under 450 KN pressure (Figure 6). The grammage of the
mat was 60 g m-2.
The hot pressed mat was sent to the shaper. The second one kept for display.
Figure 5: Wet mat
Figure 6: Dry mat after ironing.
2.2.2 Bleaching process
Three ramie mats were bleached in the same conditions as Surfboard 2, then treated
with laundry detergent , and finally fabric conditioner to increase their permeability. The
laundry detergent was Coldpower washing liquid and the commercial fabric conditioner
was Cuddly, both manufactured by Colgate Palmolive Ltd, Petone, New Zealand.
The mats were washed with 20 g L-1 of cold power in 10L then rinse and let to soak
overnight in 6 L of conditioner at 33 g L-1.
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2.1.3 Characteristics of Surfboard 3
The shaper used 3 plies, two on the deck (ramie and Cherry red Harakeke mats) and
one ramie mat on the keel. The bleaching process of the mat was not enough to get a
pure white colour, so white pigment was added to the resin on the keel as for Surfboard
2. The ramie mats were difficult to shape around the rails, and perhaps even more
difficult than the untreated mats used on Surfboard 2. The detergent/conditioner
treatment did not work as well as expected. The shaper hid defects by adding black
tape around the rails.
The mass of the surfboard was 4155 g without fins. This was a little too heavy for the
board to be regarded as “high performance.”
Surfboard 3 was tested for three times in surf conditions: twice in photographic sessions
aimed at the Scion 2007 Christmas card and once for TV1 news item. No damage was
observed during these tests, but there was minor damage to nose and rails during
storage at Scion and in moving the surfboard between rooms for display purposes.
3. RESULTS AND DISCUSSION
Construction of Surfboards 2 and 3 completed a colour-coded series that allowed
comparison between three types of construction:
(a) Blue (Surfboard 1): all harakeke wet-laid fibre.
(b) Red (Surfboard 3): a combination of plain-weave ramie fabric and harakeke wetlaid fibre.
(c) Green (Surfboard 2): all ramie plain-weave fabric.
The weight decreased as the proportion of ramie fabric increased (Fig. 7). In comparing
these weights, it is important to consider the contributions from the foam blank with
stringer (2.21 kg) and fins (0.23). These contributions are represented by the white bars
in Fig. 7.
The known weights of the surfboards, along with known area densities (grammages) of
reinforcement provided the information required for estimation of fibre fractions and skin
thicknesses (Table 1). A surface area of 0.60 m2 was assumed for each of the decks
and keels, based on interpretation of a photograph of Surfboard 1. The area of the rails
was neglected in these calculations. It was assumed that the weight of the foam blank
was the same as that of a shaped blank provided by Mike Murden, i.e., 2.208 kg
including stringer. It was assumed that the shaper achieved the same fibre fraction in
the ramie-reinforced layers of Surfboard 3 as in Surfboard 2.
According to the estimated values in Table 1, the harakeke-reinforced surface layer on
deck of Surfboard 3 contained a slightly higher fibre fraction than the deck of Surfboard
1. The difference was attributed to use of mats with different grammage: 60 g m-2 for
Surfboard 3, compared with two layers of 40 g m-2 for Surfboard 1. The lesson learnt
here was that it is better to use one high-grammage mat than two low-grammage mats.
Even higher grammages were not considered desirable, because of problems with
drapability and permeability. High-grammage mats trap pockets of resin. In future work,
it might be helpful to punch holes in the mats to allow resin to escape. Similar problems
were encountered with the ramie fabric. The shaper pointed out that the weave was
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closer than desirable. If production was shifted to a commercial basis, it would be
desirable to specify a looser weave, i.e., similar yarn linear density but a lower thread
count in both warp and weft directions. The problem of permeability is illustrated in Fig.
8, which shows holes approximately 0.5 mm square in a typical glass “four-ounce cloth”
designed for surfboards, and holes approximately 0.2 mm square in plain-weave ramie
cloth.
Figure 7: Weights of three surfboards, showing the advantages of using woven fabric
(ramie) rather than random mats (harakeke). Each surfboard was weighed with fins but
without leash. The white portion of each bar indicates the contribution from the foam,
the stringer and the fins. The coloured portion indicates the contribution from the fibrereinforced shell.
Table 1. Surfboard data. Brackets indicate assumed values.
Surfboard and part
Fibre
Fibre
weight
fraction
Fibre
volume
fraction
Composite Thickness
of this
density
-3
layer
(kg m )
(mm)
Surfboard 1 (blue)
Deck
Harakeke 0.032
0.027
1182
2.1
Keel
Harakeke 0.032
0.027
1182
1.1
Ramie
0.137
0.111
1212
0.75
Deck (surface)
Harakeke 0.042
0.036
1183
1.2
Deck (base)
Ramie
(0.137)
(0.111)
(1212)
(0.75)
Keel
Ramie
(0.137
(0.111)
(1212)
(0.75)
Surfboard 2 (green)
Deck & keel
Surfboard 3 (red)
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Figure 8. Scanned images of (left) plain-weave glass “four-ounce cloth”, (right) plainweave ramie fabric. Each square shows a portion 25 mm by 25 mm.
Low weight and high strength are just two of many requirements for surfboards. Visual
appearance is another requirement, and the red surfboard was selected for publicity
purposes because of a combination of attractive appearance and adequate
strength/weight ratio. Figures 9 to 11 show additional photos of the full set of three
surfboards. While the bold patterns of the tie-dyed ramie in Surfboard 2 are clearly
visible at a distance, the choice of a green colour was criticised by a user. The
surfboard was not clearly visible in surf, and the surfer sometimes felt he was “walking
on water”, lacking visual input to judge his stance on the board.
Figure 9. Surfboard 2. The tie-dyed ramie deck is so thin that the wooden stringer is
visible, running through the centre line from nose to tail.
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Figure 10. Surfboard 3. The random pattern of coarse and fine fibres is not obvious in
this oblique view.
Figure 10: Surfboards with shells reinforced by harakeke reinforcing mat (left), and
ramie plain-weave fabric (right).
4. CONCLUSIONS
Plain-weave fabric is better than wet-laid reinforcement, in terms of high performance
surfing, but wet-laid reinforcement offers decorative effects. A combination of fabric and
wet-laid fibre shows potential.
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5. ACKNOWLEDGEMENTS
The authors thank the Biopolymer Network Limited for funding under New Zealand
Foundation for Research Science and Technology contract BPLY0402, Mike Murden for
shaping the surfboards, and Damien Even and Kent Newman for their assistance in
testing Surfboard 2.
6. REFERENCES
Burns J, Newman RH (2006) Epoxy-biofibre composites containing epoxidised
vegetable oil. Scion Report 11533, Output 39251.
Le Guen MJ (2007) Harakeke surfboard project. Scion Report 12282, Output 41075.
Newman RH and Le Guen MJ (2008) Ramie plain-weave fabric as reinforcement for
unsaturated polyester resin. Scion Report 12813, Output 42532.
Toll S. (1998) Packing mechanics of fiber reinforcements. Polymer Engineering and
Science, 38, 1337-1350.
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