Ro-Ro ships can roll-on or roll-off cargo with self-driving power such as passenger cars and trucks, and container cargo on transport devices such as trucks or trailers on a ramp. The representative types of Ro-Ro ships are PCC (Pure Car Carrier) and PTCT (Pure Car & Truck Carrier). Ro-Ro ship is configured to load as many cargoes as possible by dividing the cargo hold into multiple card decks up and down. It is necessary to adjust the height of the car deck according to the type of vehicle being loaded. For this purpose, a number of fillers are installed on the inner deck of the Ro-Ro ship. In other words, to load high cargo such as heavy equipment on the car deck, the height between the decks must be high. At this time, the liftable car deck is adjusted using the deck lifter installed on the pillar. Existing liftable car deck structures are made of a single large plate, so it takes a lot of time and money to install and dismantle them. In this study, a hinge-type liftable car deck was designed. In addition, the overall structural integrity including the hinge was evaluated through structural analysis in accordance with the classification regulations.
A Ro-Ro Ship is a cargo ship that transports general vehicles, heavy equipment, and trucks. It does not require a separate crane or equipment, and vehicles can directly load and unload with their own power. In the middle of the 19th century, it was the first time that a train ferry capable of loading vehicles was introduced in the Firth of Forth to replace the insufficient bridge technology (Papanikolaou and Boulougouris, 2010). At that time, there was no technology to attach the lamp to the ship, so the loading and unloading lamp was installed on the ground and connected when the ship came in. During World War I, many Ro-Ro ships were built and used for logistical support. In World War II, military Ro-Ro ships (amphibious ships) appeared. Ro-Ro ships were first used for transportation purposes after World War I, when they were used for routes connecting England and France in the Straits of Dover (Berry III, 2021). Ro-Ro ship does not require separate loading and unloading equipment, so it is possible to transport cargo regardless of poor port conditions. It helped a lot in overcoming the infrastructure that was devastated after the war. Container ships are the most common and widely used in marine transportation today, but Ro-Ro ships also have strengths in vehicle transportation. According to MDS Transmodal, it is showing a trend of 3-4% increase every year (Ovstebo and Fagerholt, 2011). As shown in Figure 1, since the cargo heights of Ro-Ro ships are different, it is necessary to flexibly adjust the height of the car deck to load various types of cargo on Ro-Ro ships.
