Help with creating a run file in Autohydro for Wind overturning

Hello all,

Can anyone help me in creating a run file to include the wind overturning intact condition according to ND 0030/Rev 05?

Basically how can one define the dynamic angle to get the (A+B) >= 1.4*(B+C)?

Thanks

 

could you send the extract of the IMO criteria... i mean the Rule requirements ....

 

Hello Athvas,

It's section 10.3 from Noble Denton guidelines 0030/Rev05

Section 10.3.1: For the intact condition, the area under the righting moment curve shall not be less than 40% in excess
of the area under the wind overturning arm curve (30% for column stabilised units). The areas shall be
bounded by 0º inclination, and the dynamic angle (defined as the angle at which this condition is met).
The dynamic angle shall be less than both the second intercept and the downflooding angle.


Thanks

 

You need to plot the wind overturning arm curve in the GZ curve (which is obtained from autohydro) in the graph and the area is checked in the graph (autocad).

 

can this be written in a run file?
if so, how?

 

i haven't tried that... i use to check the areas in the autocad graph only. Autocad is much simpler than creating run file in autohydro.

 

It may be too late but:

You can simply use following limit definition in autohydro:

limit abs ratio form abs 0 to ra0 or fld >1.4

then use HMMT to apply wind force.

 

How you define the limits for IMO Weather Criteria ? for a wind pressure of 504 Pa

 

limit res ratio from roll to abs 50 or fld > 1
limit res ratio from roll to abs 50 or ra0 > 1
limit angle at equ < 16

roll imo
wind (pressure) 0.0504
hmmt wind /const /gust:1.5
solve

heel *-roll
ra /limit:attained /notes

 

Thanks for your reply. I'll try this command in autohydro and get back to you. do we need to give the vcg with fsm correction while running different loading conditions.

 

Yes. The fsm correction to be applied according to IMO IS code. If you load the tanks in different loading conditions, autohydro calculates fsm correction automatically.

 

Towing criteria using autohydro

Hi babri

Can we able to achieve the below criteria using autohydro. i am using autocad to plot the heeling lever and finding the area manually . It takes more time. If it is possible to achieve it in autohydro it will be more time consuming.
Compliance for towing criteria for tugs......

The residual area between a righting lever curve and a heeling lever curve developed from 70% of the maximum bollard pull force acting at 90 deg to the ship-length direction is not to be less than 0.09 m-rad

The residual areas under the curves are to be calculated from the 1st intercept up to an angle of 40 deg beyond the first intercept or up to the down flooding angle, whichever is less.

bh = 0.7 TH Cos Ѳ / ∆
bh - Towing heeling lever
T - Max Bollard pull
H - Vertical distance between towing hook and centre of propeller
∆ - Loading condition displacement
Ѳ – Angle of heel