Types of ships: know when to hire each one

Those who work with port logistics — directly or indirectly — need to know the different types of ships to know the ideal occasion to hire each one. After all, in what situations should you rely on a cargo ship? For what purposes is it most suitable?

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Taking into consideration the relevance of the theme to the sector, we prepared this article. Throughout the text, you will understand how the categories differ and the particularities each one presents. Read it through to the end!

What is a cargo ship?

To answer these and other related questions, we talked to Marcela Rosman, who is the CEO of Aries Shipping — a company established since 2005 in Rio de Janeiro, specializing in cargo and ship brokerage between users and service providers.

Summing it up, she points out that the “cargo ship is specifically designed to carry commodities”. “This type of ship has existed since the dawn of maritime transport, that is, centuries ago, when the first vessel was built”, shares the expert. Ever since this historical landmark, maritime transport has been fundamental. Even with advances in air transport and in the media, vessels play a major role in the global economy.

She also points out that “some ships are built to operate only on a particular route and, in such cases, naval engineers must respect restrictions such as the draft of the ports, the weather (whether there is ice or not), etc.”.

Therefore, cargo ships are generally designed to carry bulk goods, general cargo, liquids, and gas, among others. Some models support just over 4,000 containers. Their large capacity is coupled with the power of the ship engines — many can carry loads of various sizes and thousands of tons. The speed they reach varies.

What types of cargo ships are there?

In addition to general cargo ships, there are those designed to carry specific cargo, such as gas tankers, tankers, bulk carriers, and also those that carry live cargo. Regarding these categories, Rosman says they require specific care: “If they are not kept in constant activity, they can fall into disuse, because the cost per day of a stationary ship is quite high”. Check out below what they are and what they’re for.

Bulk ships

As its name suggests, the category was designed for loading and unloading bulk goods — such as minerals, coal, and grain. Most of the time, they have a rectangular-shaped deck, because this makes it easier to move items. They are suitable for products that can be stowed in the hold without an obligation to:

•    count the units;
•    use specific packaging;
•   identify any trademarks.

Oil tankers

Oil tankers, in their turn, are used to transport not only crude oil but also its derivatives, and can carry over 300,000 liters of fuels and derivatives. They carry a crew of 25 people, on average, that stay in the stern (aft) of the vessel, where there is a cockpit and other common areas, such as the refectory.

These ships feature a deck full of interconnected pipes that evenly distribute the oil in order to ensure balance. Compared to other models, tankers are wider and less deep — features that make them capable of navigating in shallow water. They have a double hull, which is useful to guarantee safety against leaks.

Gas ships

They are used to carry liquefied gases — such as LPG, LNG, ethylene, ammonia, propylene, among others. Their great mark is the presence of rounded tanks above the main deck. They can have 4 distinct types of tanks:

• independent tanks: fully support the weight of the cargo;
• membrane tanks: have thin walls, supported by the vessel structure, that can contract and expand freely;
• integral tanks: are part of the ship’s structure;
• semi membrane tanks: have rounded corners to avoid contact with the ship’s structure.

Refrigerated vessels

They are so named because of the robust refrigeration equipment in their basements. This structure serves to keep fish at the ideal temperature until they reach the refrigerators on land. Not by chance, they are essential for the practice of large-scale commercial fishing, as they avoid the waste of the product that sustains the activity.

Container ships

They are built for the transportation of cargo in containers and can be divided into two types: the running deck and the mobile. The first is designed for rolling embarkation, while the second has several holds, so the embarkation takes place with the aid of cranes from the ship or the port.

Container ships tend to have a faster loading and unloading speed than traditional freighters, and the largest in the world can carry more than 15,000 containers.

Ro-Ro ships

Ro-Ro (roll on-roll off) ships are designed to carry any loading and unloading on wheels: either on their own wheels or through equipment designed for this purpose.

“Ro-Ros that carry cars, for example, function as large garages, but can carry containers on deck or even inside holds, provided the cargo is properly tied with wire ropes so they don’t break down,” explains Rosman.

What are the prospects for the future of the cargo ship?

“If we consider protectionism to be in check, free competition is the best way to allocate resources — so trade gains are distributed in a game whose sum tends to be positive. The best way to transport large-scale cargo is and will always be via ship”, concludes Rosman.

Finally, it is a fact that different types of ships contribute in many ways to the global economy. By knowing the characteristics of each one, it is possible to identify good business opportunities and get the hiring right.

If you liked this article, take a look also at how a port intelligence service can assist with your operations!