Trim and Stability Booklet

What to expect from your engineer when ordering a stability book.

The trim and stability booklet (T&S) is a critical element for the vessel.  For barges, this may be called a loading manual.  The name of the document takes many different forms.

Think of a trim and stability booklet like this:  There are many pieces of equipment on your vessel.  And each piece of machinery came with an operator’s manual.  The T&S book is a like an operator’s manual for your entire vessel.  It specifies many important elements that tell you how to safely operate your vessel.  The T&S booklet guards against the following concerns:

• Intact Stability
  • Vessel flips over on a good day
• Damage Stability
  • Vessel flips over on a bad day when a compartment floods
• Longitudinal Strength
  • Vessel breaks in half because the structure was overloaded
• Load Line
  • Vessel sinks straight to the bottom because a compartment flooded

These scenarios all sound very scary.  They should.  That is why the T&S book is so critical and why an engineer will prepare it carefully.  The naval architect must take the physical limits of your vessel and imagine every possible way you can use it.  Based on that, they develop a typical set of operating instructions.  The T&S book should provide the following types of information.

1. Describe operating instructions for a typical mission.
   1. These are the typical loading conditions
2. Provide all the information necessary to determine your own custom loading conditions.
   1. This a regulatory requirement.  You must be able to do your own custom loading conditions with just the information in the T&S book.
3. Demonstrate that the vessel meets all regulatory requirements in each standard condition.
4. Provide some general guidance on vessel operation.

Deliverables

The deliverable is typically a written report.  Sometimes the engineer will combine this with the stability analysis report.  Sometimes the engineer separates the stability analysis from the T&S book.

• The T&S booklet tells what the limits are and shows how to check your limit. It is an operating manual for the ship.
• The stability analysis report proves that the limits were based on good math.

The T&S book is essential.  But if you ever calculated a custom loading condition by hand, you know that it is very cumbersome.  In addition to the T&S book, you may ask for a stability calculator.  This can be a piece of custom software or just a spreadsheet.  They take many forms.  They are not typically part of the regulatory requirements.

Budget

A T&S book typically takes 1 – 2 weeks to prepare.  Just the book.  There is also a stability analysis behind the entire book.  And development of hydrostatic models.  Overall, given all the background tasks, it can take 4 – 8 weeks to go from a signed contract to a final T&S book.

Schedule

Schedule is typically 1 -2 weeks for the T&S book.  And typically 4 – 8 weeks total.  Also add in some extra time for your responses.  There will be a lot of discussion with you to get information on the vessel and its typical mission.

Required Input

Soooo much input is required.  Be ready to provide the following documents.

• Current stability analysis
• Current trim and stability booklet
• General arrangement
• Any 3D models of the vessel
• Any existing hydrostatic models of the vessel
• Lines plan

In addition to that, be ready to give detailed information about your vessel’s mission.

1. What are the deadweight items?
   1. What is the weight of each item?
   2. Where are they usually stored on the vessel?
2. Think about your deadweight items.  There are more than you know.
   1. Crew weight
   2. Crew effects
   3. Spares and stores
   4. Food
   5. Everything in the bosuns store room
   6. That rebuilt Harley in the Chief Engineer’s cabin
   7. Cargo
3. What is your typical mission
   1. Operating duration?
   2. Locations that your travel to?
   3. Distance traveled?
   4. Fuel burned between refuelling?

The engineer can fill in much of this information with educated guesses.  But they charge you for all the time they spend guessing.  The more you can provide, the faster and cheaper things go.

Also, provide your preferences.  The engineer can customize the T&S book.  Anything you want included or excluded?  Did you want a computer calculator for the captain?  Did you need training and orientation on it?  These extras cost money, but some are relatively cheap.  Most important, be ready for frequent and honest communication with the engineer.