Immediate Action: Correcting an Angle of Loll

If you are asked during your MCA oral exam what immediate corrective action should be taken if a vessel is observed to have attained an angle of loll, your answer must be precise: Ballasting to a central position immediately. It is vital that you do not attempt to shift cargo or correct the list by wing tanks first, as this can exacerbate the instability of a vessel with a negative metacentric height (GM).

Understanding the Angle of Loll

For an Officer of the Watch or a Chief Mate candidate, understanding the distinction between a 'list' and a 'loll' is non-negotiable. An angle of loll is a state of unstable equilibrium caused by a negative GM. Unlike a list, which is caused by an off-center weight, a loll occurs when the ship's center of gravity (G) rises above the metacenter (M).

When G is above M, the ship is inherently unstable. If the ship heels due to external forces, the center of buoyancy (B) shifts, but because of the negative GM, it creates a heeling moment rather than a restoring one. The vessel will flop over until it reaches a new angle where the B and G are once again in the same vertical line, creating a stable, though undesirable, angle of loll.

Why the Examiner Focuses on This Topic

During your 3000GT or Unlimited level oral examinations, the examiner is testing your ability to distinguish between stability problems. If you suggest shifting cargo or filling high-side wing tanks to 'level the ship', you are potentially causing the ship to capsize. The examiner wants to see that you prioritize restoring the vessel's positive GM before attempting to address the list.

The Correct Procedure Step-by-Step

When responding to this question in your OOW oral exam, follow this systematic approach:

1. Stop all work: Cease any cargo operations or ballasting activities immediately.
2. Fill double bottom tanks: By filling central, low-positioned tanks (ballast tanks), you effectively lower the vessel's center of gravity (G).
3. Monitor the ship: As you add weight to the center, G will lower below M. As GM becomes positive, the vessel will naturally return to an upright position.
4. Avoid Wing Tanks: Never attempt to correct the angle by filling wing tanks on the 'high' side first. Doing so can cause the ship to 'flop' over to the other side violently, potentially leading to a total loss of the vessel.

Common Pitfalls and Candidate Errors

Many candidates fail this part of the MCA oral because they confuse loll with list. Here is how to avoid those traps:

• Confusing List and Loll: A list is caused by an off-center mass (stable equilibrium). A loll is caused by a lack of initial stability (unstable equilibrium).
• Incorrect First Action: Do not talk about shifting cargo. While shifting cargo can fix a list, it is far too slow and dangerous for a loll. The ship is in a state of crisis; ballast is the fastest way to add low-down weight.
• Lack of Safety Awareness: Always mention that you would notify the Master and inform the Engine Room before initiating emergency ballasting.

Practical Tips for the Chief Mate Oral

As a Chief Mate, you are expected to understand the theory behind the 'Free Surface Effect' (FSE). Remember that free surface reduces your effective GM. If your ship is already tender, a large free surface in your tanks can be the final straw that moves your G above M, resulting in an angle of loll. Always maintain your tanks pressed up or empty to minimize FSE when stability is marginal.

Conclusion: Key Takeaways

To pass this question during your examination, remember these three core points:

1. The Diagnosis: A loll is caused by a negative GM.
2. The Action: Only ballast to a central, low position to lower G.
3. The Warning: Never attempt to correct a loll by filling wing tanks; you risk immediate capsizing.

Mastering this response demonstrates to the examiner that you understand the fundamental relationship between G and M, which is the cornerstone of safe ship operations for any Officer of the Watch.