11
6463
2
2022
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SPS-B
MC_0207
Fin Positioning
No part of the fi n should be above water level during normal roll motion/under normal sea conditions.
Fins should not extend outside the beam or below the keel when in neutral position.
Fins should be placed as far outboard as possible, and NOT in-line with the propellers, to ensure avoiding possible disturbance of the water flow to
the props which in the worst case can cause vibrations / cavitation.
MC_0207
Hull Forces
All calculated values are normalised, determined by equilibrium considerations and also that various coeffi cients are inaccurate as hull design etc will
affect the actual fi n effect.
Dynamic effects such as jumps/impacts with waves, back flow closing of valve etc could further increase the hull/shaft loads. Therefore all
dimensioning should account for this by using a safety factor.
The aft top face of the fi n is deliberately made weaker than the rest of the fi n so it will break easier in case of an impact with the hull.
It is advised to strengthen the hull or ensure it is manufactured with materials suitable to sustaining impacts over the total length of the fi n within an
area of approximately 10 degrees of fi n rotation in each direction from its centre.
(NB: This is a safety measure to ensure the fi n will not break through the hull in a collision situation.)
Sleipner curved Vector Fin design comes with additional benefi ts in hull safety. Any impact with the ground will not only bend the shaft backwards and
outward, allowing the fi n to break away with less stress on the hull.
MG_0284
Bending moment
(Mx and My
components)
Shear force
(FX and Fy
components)
Axial shaft
force (fz)
Torque
moment (Mz)
Outer surface
hull