Stability calculations - wish list#

At the moment the DAVE core offers the following functionality:

  • carene tables

  • GM curve including

    • wind forces

    • full statics solving such that cranes, attached buoyancy, contact, etc are fully incorporated

  • Free fluid surfaces are included naturally. This means that there is no “free surface correction” as there is nothing to correct for using work-arounds.

  • damaged tanks are possible by setting a tank to “free flooding”

  • free trimming is possible

The stability analysis report section sets a heel angle, solves statics and then reads the moment required to impose that heel angle. From this the GZ values and wind arm can be derived.

The idea is to develop a automated workflow that applies a number of loadcases, runs them and assembles and reports the relevant results.

Applicable Codes#

IMO

0300/ND

DNVGL

Loadcases#

CODES

intact

with , without wind

pre-defined range of heel angles, to both sides

damaged single tank

pre-defined range of heel angles, to both sides

with, without wind (different wind speed than for intact)

damaged multiple tanks

0030/ND: Two adjacent compartments on the periphery of the unit shall be considered as one compartment if separated by a horizontal watertight flat within 5 m of the towage waterline

ND

User input

  • wind speed intact

  • wind speed damaged

  • free trimming

  • damaged tanks

  • (damaged tank pairs)

  • down-flooding points

To be calculated and reported#

What

CODES

area under the righting LEVER curve (GZ curve)

IMO

area under the righting MOMENT curve

DNVGL

probably an error in the code as it is compared to the wind arm.

2nd intercept angle

Area under wind overturning arm

ND

minimum initial GM value

IMO, ND

minimum GZ value at 30 degrees

IMO

angle of heel at which the maximum righting arm is reached

IMO

Intact range (0 till angle at which the GZ becomes negative)

ND, DNVGL

Down-flooding angle

IMO

Cargo overhang submergence

DNVGL

(do not include, can easily be calculated separately)

General

Add numerical data of curve in report

Option to calculate GM to both sides

Special cases#

Column stabilized units

Jack-ups

Snips#

  • image-20240319151202648

  • image-20240319151215229

DNVGL:

image-20240319153435474