Damage Control Training
Stability and Buoyancy Lessons



Contact periods allotted this LESSON TOPIC:

Classroom: 1.0 Test: 0.0

Trainer: 0.0 Total: 1.0

MEDIA: Classroom lecture with visual media


6.0 EVALUATE shipboard stability by analyzing weight and moment considerations (JTI 2.1, 3.2.1, 3.2.2, 4.2, 4.2.1, 4.2.2, 6.0, 6.1, 6.2)


6.58 DESCRIBE the ballasting system including: purpose, function, characteristics, subsystems, components and operating procedures.

6.59 LIST reasons for ballasting.

6.60 DESCRIBE common arguments against ballasting.

6.61 STATE the Damage Control Assistant's responsibilities with respect to ballasting.



I. Reasons for Ballasting

a. To maintain adequate low weight for stability

b. Off center tanks may be flooded to reduce list upon damage (counter flooding)

c. To provide a liquid layer at the shell to absorb fragments

d. Control list and trim (ex: flight operations)

e. To conduct wet well operations

f. Grounding

g. To suppress Free Surface Effect


II. Solid Ballast Systems

a. Reasons for the installation of solid ballast

1. To improve transverse stability

2. To adjust trim

3. To eliminate an inherent list

b. Types of solid ballast used

1. Lead

2. Cement

3. Iron


III. Liquid Ballasting Systems

a. Automatic (Fuel Oil Compensating System)

This system provides automatic ballasting of fuel oil storage tanks. By constantly supplying firemain water to the tanks through a reducer, the storage tanks are always full of fuel, water, or a combination of the two.

III. Liquid Ballasting Systems (continued)

b. Manual ballasting systems

1. Dedicated systems that involve only tanks and voids designated for ballasting. They have their own piping runs, pumps, etc. ("clean ballast")

2. Fuel oil tank ballasting ("dirty ballast")

a. Accomplished by using several systems that are interconnected by a manifold

b. Ballasting water is supplied to the tanks by the firemain or auxiliary saltwater systems

c. Tanks can be dewatered by the bilge stripping system or a drainage system


IV. Guidance for Ballasting

A. The following references provides guidance on ballasting:

1. Fuel oil tank sequencing section of EOSS.

2. Liquid load diagram.

3. Damage Control Book.

4. TYCOM Instructions.

5. NSTM 079, Volume I.

a. Can be used to develop a ballast bill if none of the other references apply to your ship.


V. Status Boards

A. All ships are required to maintain a liquid loading diagram at Damage Control Central and at all repair lockers, showing the status of fuel and water tanks. The value of having such a record available is that it shows which compartments contained liquids before damage, hence did not flood. It also provides a chart on which to mark up information on the extent of the flooding as this comes in via communication systems after damage.

VI. Damage Control Assistantís Responsibilities


a. Maintain awareness of ship's liquid loading condition. (Full Load - Min Ops)


b. Determine the risks associated with violating LLI and report to CHENG if necessary.

1. Hogging and sagging stresses

2. Submerging limiting draft marks

3. Survivability of beam winds and seas

4. Maintain adequate metacentric height


c. Ensure most current fuel and water report is posted daily at each repair locker and DC Central



VII. Arguments Against Ballasting


Ballasting will destroy the fuel tanks: concern that adding salt water to the fuel tanks will increase the rate and amount of corrosion. On many older ships, fuel tanks that are ballasted must be cleaned prior to putting fuel back in the tank.


The ship has never had to ballast before, it must not be necessary: CHENGs will discuss ballasting during the relief process. If fuel tanks were never ballasted in the two previous years, it is likely the new CHENG will not order fuel tanks ballasted during his/her tour.


Pumping out ballasted tanks will pollute the water: concern that fuel will be spilled when deballasting tanks. The Commanding Officer becomes liable for marine pollution violations.