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Next, the pressure tank is assembled using the lower shell (11) and the upper shell (12). First of all,
there are two points to be considered: the pressure tank should not be too high, otherwise the water
tank will not fit on top later on. Before finally gluing the shells together, place the assembled shells into
the hull and measure from the upper edge of the upper shell (12) to the upper edge of the brace (8).
This dimension must not be smaller than 27mm, neither fore nor aft.
When assembling, please note which way round the upper shell is placed on the lower shell. The
upper shell has three cover areas. The smallest of these is at the front. You can see it in the drawing
on the lower side view.
Now apply a thin bead of ABS adhesive to the outside of the cutting edge of the upper shell. It should
be continuous. Put the shells together and hold them together with adhesive tape. Once the adhesive
has cured, you can put some more adhesive into the gap between upper and lower shells, in order to
seal it properly.
Leakage test:
Now you can carry out a leakage test: Put the foam rubber gaskets (16) in place and screw the covers
on. Carefully and evenly tighten the nuts with an Allen key (but not too tight) so that the gasket is
slightly squeezed and touching everywhere. Seal the two holes of the stern tubes with insulating tape
and immerse the tank in water. Test the gaskets carefully and repair any leaks before commencing
with the task.
Installation of Bowden Cables and Tube Pieces
To control the aft side rudders and the fore fins, two Bowden cables consisting of an outer and an
inner tube are used. The outer tube must now be installed into the pressure tank and sealed with an
epoxy adhesive. To achieve a good seal between outer and inner tube, the Bowden cables were
deliberately left as long as possible. That is why the Servo for the aft side rudder is right at the front
and the servo for the fore fin is right at the back. Cut the external tube to length according to the build
plan. To strengthen the dive tank, it is double-skinned with scrap pieces (15) and ABS adhesive at the
places where the Bowden cables (14) and the pieces of tube (13) for the pump hoses are fed through.
Now you drill a 3mm hole through the tank for each of the Bowden cables and a 5mm hole for each of
the two pieces of tube. This is easily done with a hand chuck. Mark the place on the Bowden cable
that is to be at the exit place as per the build plan and roughen this area a little with sandpaper. Then
glue the Bowden cables (14) and the pieces of tube that have also been roughened (15) into the
pressure tank and take care that the adhesive is flowing completely around the tube both on the
outside and the inside of the tank and fuses with the plastic.
Installing the Pressure Tank in the Hull
As a next step, you can place the prepared pressure tank into the hull. Take particular care of the
height dimension of 27mm as per the build plan. Re-insert the stern tubes into the hull and pressure
tank and check that the dimension from the end of the stern tube to the stern of the hull is as per the
plan. The pressure tank is seated correctly if 3 to 4mm of the stern tubes in the pressure tank are still
visible so that they can be cleanly glued into place. Attach the shafts and coupling to the motors and
correct any cut-outs if the course is not quite correct so that everything can run freely. Mark the
position of the pressure tank in the hull. Now remove the pressure tank from the hull, apply ABS
adhesive to the contact areas on the floor and replace it precisely in the same marked position. Re-
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© Klaus Krick Modelltechnik Knittlingen August 2002
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