MANUFACTURING PROCESS OF REMOTE CONTROL SAILING BOAT
This
project is done for the purpose of fulfilling the requirement for Manufacturing
Technologies course in Australian National University.
The
manufacturing process began with the formation of the hull using the vacuum
forming machine. It was then followed by the construction of the deck, which
was based on the outer shape of the hull. The design of the hull was retained from the
conceptual design, which was the design based on the standard mould provided.
The standard wooden mould provided has a dimension of 466mm in length, 78.3mm
in maximum depth and 126.1mm in maximum width. The hull was manufactured using
the vacuum forming process in the workshop.
The
deck was made by a sheet of balsa wood, which was formed by cutting it in
accordance to the shape of the hull using an electric saw. It was then sanded
by the various sanders provided.
Placement of Components :
The
center of gravity of the sailing boat was then obtained followed by the
calculation of moments of the individual components that has to be placed below
the deck. A still water test was conducted after the hull was filled with
expander foam. This allowed the team to observe the water level of the hull before
the placement of individual components and predict the allowable water level
after the assembling of the components on the sailing boat.
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| Figure 1 : Hull Filled with Expander Foam |
Referring
back to the CAD assembly drawing of the sailing boat designed during the conceptual
design stage, the value of the center of gravity was obtained. The position of
the center of gravity of the sailing boat will assist in determining the
position of the keel and mast. As these two components are protuding
vertically, they have to be aligned with respect to the center of gravity.
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| Figure 2 : Placement of Components |
The
placement for these components is in line with the law of moments. That is, by
taking the point of the center of gravity as moment equals to zero, the left
side and right side of this point will be close to equilibrium, given a proportional
weight and distance distribution from the center of gravity.
Manufacture of Keel and Brass Weight :
The
keel and brass weight were then attached on to the bottom of the hull. Care was
taken such that the attachment of the keel to the hull is strong; as such
reinforcement was done using expander foam and superglue.
As
discussed in the conceptual design report, the keel and brass weight would be
used to increase the stability of the boat. Plywood was chosen as the material
of the keel as it fulfills the requirements of both light weight and tough
construction.
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| Figure 3 : Dimension of Keel and Brass Weight |
Construction of Sail and Sail Control System :
The
sails were constructed and the sail control system being implemented and
tested. The main sail and jib sail were cut using the nylon sail material
provided. With the triangular shape sail cut, the vertical part of the main
sail was rolled against the mast which is made of aluminium tube. The main sail
and the mast were then secured by stapling over the entire vertical part of the
main sail. This connection between the main sail and the mast was made to be
loose enough to allow for free rotation of the main sail.
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| Figure 4 : Main Sail on the left, Jib sail faced down on the right |
A
connection was established between the large servo with its attached reel on
top, and the main sail, using fishing line. Two hooks, positioned in symmetry
from the central line of the hull, were screwed on the deck. It can be observed
through the figures below that the reel of the servo has two layers. A fishing
line is wired across the top layer of the reel, through one of the hooks and
finally tied to the boom of the main sail. This connection on the top layer of the
reel was meant for clockwise movement of the sail. Vice versa, an anticlockwise
movement of the sail was established by wiring the bottom part of the reel to
the boom. The figure below illustrates the clockwise movement of the sail due
to displacement of the top part of the reel.
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| Figure 5 : Sail Control System |
Construction of the Rudder and Rudder Controller :
The
other steering component of the sailing boat, the rudder, was also fitted and
tested for efficiency.
Using
the aluminium sheet metal provided, the rudder was cut using the electric table
saw according to the dimensions as shown in Figure 8 below. Two holes were then
drilled on the top part of the rudder using the hand drill. A butt hinge of
25mm was then screwed on the rudder. A 1mm hole was
drilled at the top of the rudder. The position of the hole was made high to
prevent contact with the deck which could hinder
the movement of the rudder. Next, a cylindrical
screw was attached to the hole. An aluminium wire was then tied from the reel
of the small servo to one end of the
cylindrical screw. This connection allows movement of the rudder in the clockwise direction. Vice versa, another
aluminium wire was tied to the opposite part
of the reel, establishing an anticlockwise movement. The connection of the
rudder control system is illustrated in the figure
below.
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| Figure 6 :Rudder Mechanism |
Conclusion :
The
manufactured sailing boat has a tough body in its plastic construction. The
expander foam filled in the hull, layered by a deck, helps in preventing water
from entering while adding to the overall toughness of the boat. The keel and
the brass weight ensure that the boat will not capsize. The sail and rudder
control system, which both assist in the movement of the sailing boat, is proven
to work with a reasonable level of efficiency.
