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Tissues,
coverings and tapes
The construction of
our boat in fibreglass takes place with the application in the mould of
a polyester gelcoat (the colour of our boat), followed by fabric (of various
weights per square metre and various types of matting, etc.) bonded together,
welded into "form” with polyester resin. Generally, the weight
ratio of fibreglass fabric /polyester resin, is very near 45 to 55 (or
vice versa 55 to 45) as foreseen by the Registers. Reinforced, special
fabrics, aramid polyamide fabrics ( of which Kevlar is the Du Pont registered
trade mark), carbon, hybrid (many types of fibre in a fabric together)
special construction techniques, using expanded polystyrene, balsawood,
constructive capacity of the boatyard, constitute the intrinsic quality
of our boat.
If we want to make repairs after an accident, or modifications to our
boat connected to the polyester, or reinforce some points of the same,
the use of epoxy resin with the relevant additives is the right choice.
It is extremely important therefore to consider that not all fabrics are
the same (even if they have the same weight per square metre) because
many of them are prepared (dressed) to receive polyester resin, whereas
for epoxy resin you need the right ones. The costs of the fabrics, are
exactly analogous, but it is important to be certain of these combinations
of compatibility, otherwise we will have limited adherence.
The integrated use of these fabrics is also valid for wooden boats. It
is advisable during construction, repair or modification (because of the
ever greater need for robustness and lightness) they fully help the designer
and the builder by adding a very modest weight and also resolve structural
problems, considering also their adaptability and simplicity of application.
If you consider that it is possible to cover a fully stripped boat with
moisture content less than 12% to 15% in fabric to give it more strength,
resistance and in order to eliminate a mountain of problems the even limited
use of pre-cut strips, applied correctly on the boat's strategic points,
guarantees great efficiency and boat reliability.
A band of balanced glass cloth (bi-directional or warp-weft) biaxial ±
45° (weighing around 300 g/m) applied onto a motor-yacht's V hull
edges creates continuity eliminating infiltrations, small movements and
substitutes in an unbeatable way without creating water pathways and rot
as the metal edging of good memory did. The same goes for the stem, for
the transom and if need be also for the bulkheads. Naturally this application
results completely invisible in the varnishing phase and does not give
the typical problems of plastification in the future.
How much does the application of glass cloth E, biaxial ± 45°
of 300 g improve the tensile and compression strength of the wood? When
this biaxial fabric is “averagely - correctly” applied also
using Peel Ply (which improves its characteristics of impregnation and
finish - in other words it reduces the time needed following final preparation)
and considering a 3 mm Mahogany plywood, you obtain almost a doubling
of the tensile and compression strengths, that is to say we have a resistance
to these forces equal to a 6 mm plywood.
You may consider that wanting to apply and double these forces on an analogous
6 mm plywood we will apply 2 layers of biaxial cloth and have a resistance
similar to a 12 mm plywood, and so on.
Longitudinally, solid wood (as all solid woods) has truly exceptional
resistance characteristics, while across the grain resistance is around
10 times less.
This is really the reason for choosing biaxial cloth because working at
“X” across the grain all the fibres contribute to the structural
resistance whereas in case of bi-directional cloth around 50% of the same
(meaning the longitudinal fibres) would not increase the resistance we
wanted to obtain.
Therefore it is evident that wanting a reinforcement against a shake in
a solid Mahogany board a 300 g a biaxial cloth for each 8/10 mm thickness
is sufficient (with lighter wood, such as Douglas or Spruce, consider
2 mm or 3 mm more) whereas to reinforce longitudinally from plank to plank
refer to the table used for marineply.
To repair fibreglass when there are dents, splits, cracks, large osmosis
or delamination damage, intervention with epoxy resin represents the right
professional choice. If you consider we have removed 4 mm of laminated
material the new application with C-systems' 10 10 CFS or C-systems' 10
2 combined with biaxial cloth gives our boat an integrity similar to when
it was new.
The same application is indicated in joining the false keel with the planking.
The same operation can be carried out also on new or working boats, first
making a connecting edge to obtain the maximum strength and the best performance
of the mechanical characteristics of the cloth. It is interesting to note
that a glass cloth of around 150 to 200 g/m, with C-Systems' 10 10 CFS,
can be applied also to the parts that are to be visible such as the transom
boards, the cabin, and even the topsides.
It is a good idea to protect the whole operation with a complete transparent
varnish application with SPINNAKER or with NAUTILUS Two Pack Varnish.
Take into account that preferably every angle to cover with glass cloth
should previously be joined, making an edging with Microfiller Powder.
Therefore also on our wooden hull, as on the GRP one we can exploit during
construction, as well as when in use, a series of interventions aimed
at eliminating a troublesome and repetitious maintenance and improving
the boat’s quality.
Mono-directional fabrics, as the name indicates, work in one direction,
their fibres are arranged along one axis (like the wooden plank that is
highly resistant lengthways and not so across the grain) and are applied
along the stress direction, oriented along its direction. So in parity
to the stress the weight of the fabric used is around half. It is necessary
to keep in mind that the aramid fabric must work in a sandwich. What does
that mean? That before applying the aramid it is a good idea to put a
glass cloth on that surface and after the aramid layers all must be covered
again with a glass cloth. Carbon fibre fabric and aramid fabric have performances,
weight for weight and same structure, about twice those of glass fabric.
The aramid fabric is extendible, penetration-resistant (bullet-proof jackets)
they lengthen; the carbon ones are not compressible (almost), rigid, monolithic
(formula one racing car shells). These characteristics when used correctly
allow construction with superlative performances.
Weaving together various fibre qualities (glass + carbon, glass + aramid,
carbon + aramid + glass) you obtain hybrid fabrics where the combination
of the various qualities enhances in the best way the characteristics
of the fibres used.
For complex supplies such as construction and design we offer a consultancy
service with fabric producers to supply the various types and weights
of glass, carbon, aramid and hybrid fabrics in various configurations.
The offer of these products is of the highest quality and the fabrics
are certified to offer the maximum guarantee and performance.
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