Connection Of Thrust Tunnel To Ship's Hull; Grid Bars In The Tunnel Openings - Vetus BOW410HM Manuel D'utilisation Et Instructions D'installation

Connection of thrust tunnel to ship's hull

The manner, in which the thrust tunnel is connected to the
ship's hull, is of great influence to the actual performance
of the bow thruster and to the drag that the hull produces
when under way.
Direct connection of the tunnel to the hull, without a fairing, pro-
duces reasonable results.
A
A The connection to the hull can be abrupt.
B It is better to make the connection rounded with radius 'R' of
about 0.1 x D.
C It is even better to use sloping sides 'C' with dimensions 0.1
to 0.15 x D.
Connection of the thrust tunnel to the ship's hull with a fairing
results in lower hull-resistance during normal sailing.
A
A The connection with a fairing can be abrupt.
B It is better to make the connection with a fairing rounded with
radius 'R' of about 0.1 x D.
C The best connection is with a fairing using sloping side 'C'
with dimensions 0.1 to 0.15 x D.
Length 'L' of the fairing should be between 1 x D and 3 x D.
This fairing should be embodied in the ship's hull in such a way
that the centerline of the fairing will correspond with the antici-
pated shape of the bow-wave.
12
12.0202
B
R = 40 mm C = 40 .. 60 mm
B
R = 40 mm C = 40 .. 60 mm
D = 400 mm
L = 400 .. 1200 mm
: min. 0˚
max. 15˚
Operation manual and installation instructions Hydraulic bow thruster 410/ 550 kgf, ø 400 mm
If the connection of the thrust
tunnel and the ship's hull is to
be made with a sloped side, it
should be executed in accor-
dance with the drawing.
Make the sloped side (C) with a
length of 0.1 to 0.15 x D and
make sure that the angle
between the tunnel and the
sloped side will be identical to
the angle between the sloped
side and the ship's hull.
C

Grid bars in the tunnel openings

C
Although the thrust force will be adversely affected, grid bars
may be placed into the tunnel openings, for protection of the
thruster.
In order to minimise as far possible the ill effects to the thrust
power and the hull's resistance whilst under way, make sure
that:
• no more than 4 grid bars per opening will be fitted
• the bars should have a rectangular section, as shown in the
drawing, as well as a certain overlap (
• the bars should be positioned perpendicularly to the shape
of the bow wave to be expected.
Protection of the bow thruster against corrosion
To prevent corrosion problems, do not use copper based
anti-fouling. Cathodic protection is a 'must' for the protec-
tion of all metal parts under water.
In order to protect the bow thruster tailpiece against cor-
rosion, the tailpiece is supplied with a zinc anode.
D = 400 mm
C = 40 .. 60 mm
=
=
= Sharp
: min. 0˚
max. 15˚
).