Exercise No. 44: Cargo Ship
Transfer the following verbal description into an ERM
a) One Ship (Ship-#) has one Crew (Perso-#). A Crew is uniquely assigned to one Ship. One Captain (License-#) is responsible for one Ship. One Ship can only be commanded by one Captain.
b) A Crew has many Sailors (Sailor-#) but only one Steerman (Form-#). A Captain uniquely commands one Crew as one Crew can only have one Captain. Sailors and the respective Steerman work uniquely for one Crew.
c) A Captain can only have one contract with one Shipping Line (Comp-#). However a Shipping Line can employ more than one Captain. A Shipping Line owns many Ships. Ships are also owned by Joint Ventures of Shipping Lines.
d) Ownership means that Ships need to be repaired by Dockyards (Dock-#). It is not necessarily important that Ships are repaired by a specific Dockyard. However Ships are built in one Dockyard only.
e) Ships can be classified as a Cargo Ship, a Tanker or a Cruise Ship. One Cargo Ship is loaded by one or more Sailors. Tankers and Cruise Ships have to fulfil various Security Requirements (SecReq-#).
f) The loadings of Cargo Ships are classified as Freight (Ident-#). Freight is controlled by the only Custom Office. The Custom Office informs its specific Harbour (Harbour-#). Each Harbour has its own Custom Office.
g) Ships enter Harbours. The specific Maritime Authority (Author-#) checks the origin of Ships, while they enter the Harbour.
h) The Maritime Authority sets standards about various Security Requirements, which need to be fulfilled. To each Maritime Authority belongs one Custom Office and one Coast Guard (Guard-#).
i) The Weather Service (Weather-#) alarms Coast Guards and informs Steersmen.
j) Coast Guard rescue one or more Crew, which have come into trouble.