020574.06
23
vetus®
Installation instructions thruster RIM DRIVE 250 mm
3 .3 Connection of thrust tunnel to ship’s hull
t
ip
:
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. 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.
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 accord-
ance 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 be-
tween the tunnel and the sloped
side will be identical to the angle
between the sloped side and the
ship’s hull.
N.B. A scallop is mainly used in the hull of steel vessels, but is less
common in GRP boats.
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 centreline of the fairing will correspond with the anticipated
shape of the bow-wave.
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 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:
Do not fit more bars per opening than is indicated in the drawing.
The bars must overlap a certain amount.
The bars must be installed so that they stand perpendicular to the
expected wave form.
ø ...
3 mm (
1
/
8
”)
min. 20 mm (
3
/
4
”)
max. 40 mm (1
1
/
2
”)
ca. 0.7 x 0.7 mm
(
1
/
32
” x
1
/
32
”)
=
α
α
: min. 0º
max. 15º
90º
Overlapping
The bars must have a rectangular cross-section.
Do not fit round bars.
3 .4 Grid bars in the tunnel openings
4 x
250 mm (10”)
4 x
Instead of a scallop and ‘eyebrow’
bump fairing can be placed just
in front of the tunnel opening.
A
D
D = 250 mm
(9
13
/
16
”)
R = 25 mm
(1”)
C = 25 ... 38 mm
(1
...
1
1
/
2
”)
R
R
B
C
C
D
R
R
C
A
B
C
D = 250 mm
(9
13
/
16
”)
R = 25 mm
(1”)
C = 25 ... 38 mm
(1
...
1
1
/
2
”)
D
L
=
α
α
: min. 0º
max. 15º
D = 250 mm (9
13
/
16
”)
L = 250 ... 750 mm (10 ...30”)
C
C
β
γ
γ
β
Sharp
C = 25...38 mm (1...1
1
/
2
”)
D = 250 mm (9
13
/
16
”)
β
=
β
γ
=
γ
ENGLISH
