Vetus BOWB285 - 3.3 Connection of thrust tunnel to ships hull; 3.4 Grid bars in the tunnel openings

18 020814.02
Installation manual BOW PRO Series Thrusters: BOWB285 - BOWB300 - BOWB320
DL
=
α
α : min. 0º
max. 15º
D = 300 mm (11
13
/
16
”)
L = 300 ... 900 mm (12 ...36”)
A
D
D = 300 mm
(11
13
/
16
”)
R = 30 mm
(1
3
/
16
”)
C = 30 ... 45 mm
(1
3
/
16
”
...
1
3
/
4
”)
R
R
B
C
C
D
R
R
C
A B C
D = 300 mm
(11
13
/
16
”)
R = 30 mm
(1
3
/
16
”)
C = 30 ... 45 mm
(1
3
/
16
”
...
1
3
/
4
”)
C
C
β
γ
γ
β
Sharp
C = 30...45 mm ( 1
3
/
16
”...1
3
/
4
” )
D = 300 mm (11
13
/
16
”)
β = β
γ = γ
3.3 Connection of thrust tunnel to ship’s hull
tip:
The manner, in which the thrust tunnel is connected to the hull,
has a great inuence on the actual performance of the bow
thruster and to the drag the hull experiences when underway.
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 boat'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.
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 antici-
pated shape of the bow-wave.
3.4 Grid bars in the tunnel openings
Although the thrust force will be adversely aected, grid bars may be
placed into the tunnel openings, for protection of the thruster.
In order to limit the negative eect of this on the thrust and on hull
resistance during normal operation as much as possible, the follow-
ing must be taken into account:
4 x
(9
13
/
16
”)
300 mm
(11
13
/
16
”)
- The bars must have a rectangular cross-section.
- Do not t round bars.
- The bars must be installed so they are perpendicular to the ex-
pected waveform.
=
α
α : min. 0º
max. 15º
90º
Overlap
- Do not t more bars per
opening than is indicated in
the drawing.
- The bars must overlap a cer-
tain amount.
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
”)
ENGLISH