i. Sagging. When the vessel is loaded heavily midships.
j. Hogging. When the vessel is loaded heavily on the bow and stern with nothing midships.
a. Self-propelled. These barges move under their own power and are used in inland and coastal
waterways. They must maintain a crew at all times.
b. Nonself-propelled. They must be moved by tugboats and can be used for temporary storage. They
are equipped with their own pumping system.
Most tankers have two pumping systems.
a. Centrifugal pumps for off-loading the cargo.
b. Gear or piston pumps for stripping the cargo tanks dry.
Most tankers have the capability to carry up to five different products. Ship tanks are arranged abreast ad
numbered from bow to stern.
NOTE: The instructor will point out
ad numbering system using
a. Multileg mooring systems.
b. Single point mooring systems (mono buoy).
c. Jetties: Jetties are used when the water depth or the shore line is unsuitable for bringing in tankers.
d. Docks and Piers: Docks or pier are the most secure for unloading tankers.
(1) Security is easier to maintain.
(2) Access to the tanker is easier in case of emergency and for maintenance.
(3) They are protected from winds and tide.