Your vessel is listing to starboard at a steady angle of approximately 8°. The deck officer believes this is a list due to off-centre cargo but the second officer suspects angle of loll. How do you distinguish, and what are the correct actions?

A. ANGLE OF LOLL vs LIST — IDENTIFICATION AND RESPONSE: DISTINGUISHING FEATURES: (1) LIST (caused by off-centre weight): (a) The vessel rests to one side; (b) GM is POSITIVE; (c) The GZ curve is displaced sideways but still positive; (d) Filling a tank on the high side (away from the list) will CORRECT the list; (e) The vessel has a definite "preferred" upright position but is offset by the asymmetric loading; (2) ANGLE OF LOLL (caused by NEGATIVE GM): (a) The vessel has ZERO or NEGATIVE GM; (b) The GZ at zero degrees is ZERO; (c) The vessel has no stable upright position — it lolls to one side where the GZ curve has positive values; (d) The vessel may flop between loll to port and loll to starboard; (e) IDENTIFYING CHARACTERISTIC: if you forcibly push the vessel further to the loll side — it continues to heel further. If you push a listed vessel — it resists and returns; HOW TO DISTINGUISH ON THE VESSEL: (1) Look at the GZ curve from the loading computer: is GM positive (list) or zero/negative (loll)?; (2) Apply a small external force: does the vessel resist (list) or comply (loll)?; CORRECT ACTION FOR LOLL: (1) DO NOT FILL HIGH-SIDE DOUBLE BOTTOM TANKS FIRST: the counter-intuitive nature of loll. Adding ballast on the high side RAISES the centre of gravity FURTHER — makes GM MORE negative — the loll worsens. The vessel may VIOLENTLY FLOP to the opposite side; (2) CORRECT ACTION: add ballast SYMMETRICALLY to the LOWEST point first. Fill lowest double bottom tanks evenly port and starboard to lower G and raise GM above zero; (3) NOTIFY DPA: this is a serious stability situation.

B. Fill the high-side (port) double bottom tanks immediately. Adding ballast to the high side always corrects any form of list or loll.

C. An 8° list at sea is normal and acceptable. No action is required unless the angle increases beyond 15°.

D. Open the cross-flooding valves to transfer ballast from the starboard to the port tanks. Cross-flooding always corrects asymmetric stability issues.

A. IS CODE CRITERIA — GZ AT 30° DEFICIENCY: THE SIX IS CODE CRITERIA (MSC.267(85) — IS Code 2008): the International Stability Code mandates SIX stability criteria that ALL must be satisfied: (1) Area under GZ curve from 0° to 30° ≥ 0.055 m·rad; (2) Area under GZ curve from 0° to 40° ≥ 0.090 m·rad; (3) Area under GZ curve from 30° to 40° ≥ 0.030 m·rad; (4) GZ AT 30° ≥ 0.200m; (5) MAXIMUM GZ at angle ≥ 25°; (6) GM₀ ≥ 0.150m. FAILING ONE CRITERION MEANS FAILURE: all six criteria must be satisfied simultaneously. A GZ at 30° of 0.18m (vs required 0.20m) is a FAILURE — the vessel does NOT meet IS Code intact stability criteria. THE VESSEL CANNOT DEPART: it would be UNSEAWORTHY for the intended sea voyage. REMEDIES — HOW TO CORRECT THE DEFICIENCY: (1) REDUCE CARGO: if cargo is high in the vessel, shifting weight lower increases the GZ at 30°; (2) LOWER THE G: reduce KG by: (a) Adding low ballast (double bottom tanks); (b) Removing top-heavy weights; (c) Shifting cargo lower; (3) INCREASE BEAM LOADING: for certain hull forms, a different loading pattern affects the GZ curve shape; (4) REDUCE FREE SURFACE: if slack tanks are contributing to reduced GM — fill or empty tanks to remove free surface effect; DOCUMENTATION: the master must not sail with a stability calculation showing non-compliance. This is ISM non-conformity — notify DPA. LEGAL: departure with known stability non-compliance = MSA 1995 Section 58 offence (taking an unseaworthy ship to sea).

B. The vessel is close enough to the 0.20m requirement. A margin of 0.02m is within normal calculation tolerance and the vessel can depart.

C. Consult the charterer. As the cargo interests are driving the loading plan, the charterer is responsible for stability compliance.

D. Only the stability program minimum acceptable values matter for commercial voyages. IS Code criteria are guidelines, not mandatory requirements.

A. LOAD LINE CONVENTION — WNA MARK AND NORTH ATLANTIC: LOAD LINE CONVENTION 1966 (AS AMENDED): establishes mandatory minimum freeboards (maximum permitted draughts) based on vessel type, size, and the season/area of operation. WNA MARK (WINTER NORTH ATLANTIC): (a) DEFINED AREA: north of 36°N latitude and east of 40°W longitude (approximately north of the Canary Islands to the west of the Greenwich meridian); (b) THE WNA MARK APPLIES: in this area between 1 November and 31 March (Northern Hemisphere winter); (c) WNA FREEBOARD REQUIREMENT: the WNA freeboard is GREATER than the Winter (W) freeboard. The vessel must be loaded to a draught that puts the WNA mark at or above the waterline; (d) WHY MORE CONSERVATIVE?: the North Atlantic in winter is one of the most severe sea areas in the world. Higher freeboards provide: (a) Greater reserve buoyancy against green water; (b) Reduced wave impact loads on hatches and deck fittings; (c) Improved stability as hull volume is retained above water; THE SEASONAL ZONE MAPS: ICLL Annex II shows seasonal zones and areas. Masters must check the zone/area applicable to their route and season. THE MASTER's OBLIGATION: (1) Before loading — calculate the maximum permitted load based on the applicable zone mark for the passage; (2) For a November North Atlantic crossing: load to the WNA mark; (3) If the route passes through different seasonal zones — the vessel must not exceed the mark for the most restrictive zone the vessel will enter; (4) DOCUMENT: the departure draught and the applicable mark must be recorded.

B. The WNA mark applies year-round in the North Atlantic. The seasonal calendar has no bearing on when the WNA mark must be applied.

C. The WNA mark is advisory only. Masters may load to the Winter (W) mark for commercial efficiency in the WNA zone.

D. The Load Line Convention applies only to the initial port of departure. If the vessel loads within the W mark, it may freely transit the WNA zone regardless of actual draught.