Damage Stability Analysis

What to expect from a damage stability analysis.

Damage stability analysis is required to determine the stability limits of your vessel.  This is typically for submittal to regulatory bodies for approval.  Damage stability analysis involves researching regulations to determine which sets apply to your vessel.  Damage stability analyses are usually very involved and detailed.  Not only must the engineer determine the loading conditions of your vessel, but the engineer must also determine a range of possible damage scenarios for the vessel.  This will require intensive and detailed knowledge of the vessel structure and subdivisions.  There are two primary types of damage stability analysis:

• Deterministic Damage Stability
• Probabilistic Damage Stability

Probabilistic damage stability is required by the IMO.  Any vessel going on international voyages or going beyond the 12 NM boundary line must meet probabilistic damage stability requirements.  This is important because probabilistic damage stability involves considering literally hundreds of damage scenarios.  This is only efficient with computer automation.  Several hydrostatic software packages include special add-ons for this analysis.  Ask if your naval architect has this add-on.

Deterministic damage stability is the alternative form of analysis.  Some national regulatory bodies still require this.  The specifics depend on your individual scenario.  Deterministic damage stability is much easier to analyse.  The naval architect only considers likely scenarios.  There are only a few dozen damage scenarios to consider.  However, the form of analysis is more restrictive on your structural arrangement.

Deliverables

The output from this task is typically a report.  The report normally includes several other types of stability analyses as well.  This report is then submitted to the regulatory body for approval.  You should expect some additional work from the engineer to address any comments the regulatory body may have.

Budget

An experienced naval architect will require 2 – 4 weeks to complete the analysis, depending on available information.  The engineer will use hydrostatic software to analyse the vessel for a variety of loading conditions.  This also may require developing a hydrostatic model.  Model development may require an additional 1 – 2 weeks.

Schedule

In addition to the engineer’s time, plan some extra time for yourself.  The engineer will have several questions that arise as they develop the applicable regulations.  You should be prepared with information about typical voyage lengths, burn-ballast sequences, typical load-out, and general marine operations.  If you have a shore-side captain they will be very helpful.

Required Information

The following documents will be especially helpful.

1. General Arrangement
2. Stability Booklet
3. Lines Drawing
4. Any 3D models of the vessel
5. Tank plan
6. Tank capacity table
   1. Typical operating region