G'day Phillip
Good to hear from a fellow member in Australia.
My interest is in yachts but the National Standard for Commercial Vessels here in Australia has some guidance if that is of any help.
My interest is in yachts where they allw yachts to sail at an angle of heel that represents 50% 0f the maximum righting moment of the hull.
5.7 HEEL DUE TO WIND
5.7.1 Assumptions When Calculating Heeling Moment
The following assumptions shall be made when calculating the heeling moment due to the effect of a beam wind acting on the vessel’s lateral profile area.
5.7.2 Vessel Lateral Area
Where vessels are fitted with portable side screens or other similar fittings that add to the profile area, they shall be included when determining the vessel’s lateral profile area.
5.7.3 Wind Pressures
The applicable wind pressure to be used in the heeling moment calculation shall be taken from Table 15.
Table 15 — Wind Pressures
Operational Area Category Wind Pressure (Pa) Wind Speed (knots)
A & B 600 57- 64
C 450 50 -55
D 360 45- 49
E 300 40 - 45
5.7.4 Heeling moment calculation
The heeling moment due to a beam wind shall be calculated using the following formula:
MW= PAh cosθ
1000g
where
MW
=
The wind heeling moment at an angle of heel θ in tonne-metres.
P
=
The applicable wind pressure, in Pascals, for the vessel’s area of operation.
A
=
The lateral profile area, in square metres, of the vessel above the design waterline.
h
=
The vertical distance, in metres, from the centre of area Ato the centre of the projected lateral underwater area.
g
=
The acceleration due to gravity, 9.81 m/s2
θ
=
The transverse angle of heel of the vessel in degrees.