2. Based on your experience, what are the disadvantages of double-hull tankers compared to single-hull tankers?
A. Larger, lightweight, beam and draft.
More expensive to build.
More expensive canal and port expenses.
Today's market offers no compensation for higher costs of DH tanker.
B. Ballast tanks have large surfaces coated with sophisticated and expensive coating: need continuous monitoring and maintenance.
Cleaning of ballast space after a possible leakage.
Higher building cost.
D. Excessive cost for no gain in safety or environmental preservation.
Reduced cargo capacity.
Increased ballast (non-earning).
Increased port dues and insurance costs due to increased gross registered tonnage (GRT).
Increased coating areas in ballast spaces.
Heavier (not necessarily stronger) hull structure.
Potential for hydrocarbon leakage to ballast spaces. Potential for explosion.
Increased longitudinal forces.
Increased transverse free surface.
Poor accessibility for inspection and maintenance in double bottom.
Poor initial, static, and dynamic stability.
Extra maintenance costs.
Structure will not withstand forces due to collision or grounding.
Alternate design should be considered.
No return on higher cost. Most oil majors continue to embrace substandard tonnage at low freight cost.
E. DH vessels need more resources to properly manage them. Inadequate coating maintenance, structural problems if vessels built to class rules only, and stability problems may lead to problems for the industry.
More critical stability.
Higher construction cost.
Ballast tank coating critical issue.
Ballast tank ventilation difficult.
Difficult to salvage after hard grounding.
Greater beam or freeboard.
F. More equipment required to monitor void spaces.
Reduced cargo carrying capacity.
More surfaces to maintain.
For larger vessels, not much advantage in way of environmental protection.