Grid Bars In The Tunnel Openings; Installation Of The Thrust Tunnel - Vetus BOW PRO Série Instructions D'installation

3 .4

Grid bars in the tunnel openings

Although the thrust force will be adversely affected, grid bars may be
placed into the tunnel openings, for protection of the thruster.
Do not fit more bars per opening than is indicated in the drawing.
ca. 0.7 x 0.7 mm
( 1 / " x
32
min. 20 mm (
max. 40 mm (1
3 mm ( 1
The bars must have a rectangular cross-section.
Do not fit round bars.
3 .5

Installation of the thrust tunnel

Drill 2 holes in the hull, where the
centreline of the thrust tunnel will
be, in accordance with the diam-
eter of the marking tool.
Pass the marking tool (home-made)
through both pre-drilled holes and
mark the outside diameter of the
thrust-tunnel on the hull.
D [mm] (inches)
Alumi-
Steel GRP
nium
134 136
-
(5 9 / ") (5 23 / ")
32 64
Dependent on the vessel's con-
struction material, cut out the
holes by means of a jigsaw or an
oxy-acetylene cutter.
Install the thrust-tunnel.
24
020803.01
2 x
125 mm
1 / ")
32
3 / ")
4
1 / ")
2
/ ")
8
D
In order to limit the negative effect of this on the thrust and on hull
resistance during normal operation as much as possible, the follow-
ing must be taken into account:
The bars must overlap a certain amount.
ø ...
The bars must be installed so they are perpendicular to the expected
waveform.
Polyester thrust tunnel:
Resin: The resin used for the polyester thrust tunnel is Isophtalic
polyester resin (Norpol Pl 2857).
Pre-treatment: The outside of the tunnel must be roughened. Re-
move all of the top surface down to the glass-fibre. Use a grinding
disc for this.
Important: After the tunnel been sawn to length, treat the end of
the tube with resin. This will prevent water seeping in.
Laminating: Apply a coat of resin as the first coat. Lay on a glass-
fibre mat and impregnate with resin. Repeat this procedure until
you have built up a sufficient number of layers.
A polyester thrust tunnel should
be finished as follows:
• Roughen the hardened resin/
glass-fibre. Apply a top coat of
resin.
• Treat the side of the tunnel
which comes into contact
with water with 'epoxy paint'
or 2-component polyurethane
paint.
• Then apply anti-fouling treat-
ment if required.
vetus® Installation instructions BOW PRO Series Thrusters: BOWA0361 and BOWA0421
Overlap
=
α
α : min. 0º
max. 15º