| 摘要 |
<p>Vessel comprising a hull o f a substantially clo sed surface having at deck level a lifting crane, ballast tanks within the hull and a ballast control unit for admitting water to the ballast tanks for changing the draft of the vessel, wherein the hull has a narrow lower section having first width over a height from keel level to a widening level, and a top section have a larger width than the lower section, extending from the widening level upwards towards deck level, wherein the ballast control unit is adapted to ballast the vessel to have a relatively shallow draft level in a transit mode, so that the wide top section is above water level, while the vessel is traveling, and to ballast the vessel to a relatively deep draft level in a lifting mode such that the widening level is below water level, at least when the vessel is substantially stationary and the crane is in its lifting position. The shallow draft mode provides for increased transit speed and improved motion characteristics for better operability, such as during pipe lay operations. The low draft level provides improved stability during lifting operations.</p> |
