Quick BTH 513 Installation And Use Manual page 22

4 - Installation requisites
4.0 - Installation requisites propellers
minimum 0.75
times tunnel Ø
BARYCENTRE
22
A B
L 1
L 2
INSTALLATION AND USE MANUAL BTH 513 - REV001A
• The position of the tunnel will depend on the
interior and exterior shape of the boats bow.
• Optimal positioning of the tunnel will be in
the bow and as low as possible, at least 0.75
times the tunnel diameter from the waterline.
• To avoid cavitation in the propeller, the tun-
nel must be positioned as low as possible.
• The lever effect in the boat is proportional
to the increase of the distance (L1 and L2)
between the barycentre and the position of
the tunnel A and B.
F
For greater lever effect prefer position
B to position A.
• An increase in the length of the tunnel incre-
ases the effect of the loss of charge, decrea-
sing the nominal driving force.
• To limit losing thrust, the optimal length is
equal to 3-4 times the tube diameter; a ratio
of up to 6 can be tolerated.
BTH 513
EN