A. Classification by ship tonnage: for bulk cargo ships carrying grain, cement, steel, mineral sand, etc., they are usually divided into the following levels:

1. Handy bulk carrier: refers to bulk carriers with a deadweight of about 20000-50000 tons, of which vessels with a deadweight of more than 40000 tons are also called handy bulk carriers. As we all know, dry bulk cargo is a bulk cargo by sea. These ships with relatively small tonnage have strong adaptability to channels, canals and ports, moderate deadweight tonnage, and are often equipped with loading and unloading equipment, which is convenient and flexible to operate. Therefore, they are called "handy".

2. Panamax bulk carrier: as the name suggests, it refers to the largest bulk carrier that can pass through the Panama Canal under full load, that is, it mainly meets the relevant regulations on canal navigation with a total length of no more than 274.32 meters and a model width of no more than 32.30 meters. According to the needs, adjust the ship's size, ship type and structure to change the load capacity. The load capacity of this type of ship is generally between 60000 tons and 75000 tons.

3. Capesize bulk carrier: refers to a bulk carrier with a deadweight of about 150000 tons, which mainly transports iron ore. due to size constraints, it is impossible to pass through the Panama Canal and Suez Canal, so it needs to bypass Cape of good hope and Cape Horn. Taiwan Province calls it the "Cape" type. In recent years, the Suez Canal authorities have relaxed the draught restrictions of ships passing through the canal, and most of these ships can pass through the canal with full load.

4. Lake bulk carrier: refers to a bulk carrier sailing through the St. Lawrence waterway in the five Great Lakes region at the junction of the United States and Canada, mainly carrying coal, iron ore and grain. This type of ship shall meet the navigation requirements of St. Lawrence waterway in terms of dimensions. The total length of the ship shall not exceed 222.50 meters, and the width of the ship shall not exceed 23.16 meters. No part of the bridge shall extend out of the ship, and the draft shall not exceed the maximum allowable draft of major waters. The height from the top of the mast to the water surface shall not exceed 35.66 meters. This type of ship is generally about 30000 tons, and most of them are equipped with lifting and unloading facilities.

5. Small bulk carrier:Small bulk carriers refer to bulk carriers with a total carrying capacity of 20000 ~ 27000 tons. The maximum length shall not exceed 222.5m, the maximum ship width shall be less than 23.1m, and the maximum draft shall be less than 7.925m.

B. According to the different types of goods loaded, dry bulk carriers can be divided into ordinary dry bulk carriers, special dry bulk carriers, special dry bulk carriers, large hatch bulk carriers, etc.

1. ordinary dry bulk carrier

Generally, the bulk carrier is a single deck and stern type, and the cargo hold section is octagonal. Due to the single type of cargo transported, the requirements for compartment separation are not high. In addition, the proportion of various bulk cargo varies greatly. Therefore, the cargo hold volume of dry bulk cargo ships is large to meet the needs of loading light cargo. If heavy cargo needs to be loaded, the method of compartment loading or the same arrangement of large and small compartments shall be adopted.

The hull structure of dry bulk carrier is strong to meet the needs of concentrated load. There are corresponding loading and unloading equipment on the port wharfs where large tonnage dry bulk carriers dock. Therefore, dry bulk carriers with more than 40000 tons, especially those that carry out special line transportation between specific ports, generally do not set up cargo lifting equipment.

2. special dry bulk carrier

Special purpose bulk carrier is a dry bulk carrier designed and manufactured according to the special requirements of some bulk and large quantities of bulk cargo for maritime transportation technology, mainly including coal carrier, bulk grain carrier, mineral sand carrier and bulk cement carrier. They have their own characteristics.

The ship type of the coal carrier is closest to that of the ordinary bulk carrier, and there is no good ventilation equipment on the ship to prevent the coal from heating and spontaneous combustion. The bulk grain carrier's cabin capacity coefficient is larger than that of ordinary bulk carriers, because the bulk grain stowage factor is larger; The bulk grain will gradually sink during the ship navigation. In order to limit its free effect. Generally, the cargo hatch wall of open grain ships is raised and the cargo hatch size is reduced. The surface area after cargo settlement shall be limited to the hatch. The volume of cargo hold required by the ore carrier is not large, because the stowage factor of ore is small; However, its load is relatively concentrated. In order to properly improve the center of gravity of cargo, improve the performance of the ship, and facilitate cargo handling, the ship is often lifted. In addition, longitudinal watertight barriers are set at both sides of the cargo hold, so that the cargo hold has a smaller bucket shape and its hull structure has greater strength. The deck of a bulk cement ship is not equipped with a boom type cargo handling device, but is equipped with pneumatic or mechanical cement handling equipment for handling cement; In order to prevent the bulk cement from color rising and water wet caking, the cargo hatch is designed to be small, and there is no dust collecting room in the middle of the ship or an air filter is installed on the hatch cover. The upper deck and cargo hatch are strictly watertight.

3. dual purpose dry bulk carrier

Bulk carrier is designed and manufactured according to the special requirements of some specific bulk or bulk cargo for maritime transportation technology, and has a variety of shipping functions.

It mainly includes the following two types.

① Vehicle - dry bulk carrier: this type of vessel is equipped with several layers of suspended or folding vehicle decks, equipped with portable hatch covers, for loading vehicles. The vehicle deck is generally in a grid patterned iron plate structure to reduce weight. When bulk cargo is loaded, the hatch cover can be lifted to the deck, and the vehicle deck can be folded up and hung under the main deck or folded close to the transverse bulkhead.

② Mineral bulk oil dual-purpose ships: these ships have large tonnage and rich cabin capacity. The middle is the ore or other cargo hold, with a large hatch to facilitate the grab up and down; There are oil tanks on both sides, which can use the off-season oil loading of return trip and mineral sand and bulk cargo trade to improve the economic effect of ship operation. In addition, according to the source of goods, the common ships of this kind include mineral oil dual-purpose ships and bulk oil dual-purpose ships.

4. special dry bulk carrier

Special dry bulk carriers mainly include the following three types.

① Large hatch dry bulk carrier: the cargo hatch width of this kind of ship is more than 70% of the ship width, and it is equipped with cargo lifting equipment. It can not only load bulk cargo, but also load wood, steel, rubber, mechanical equipment, newsprint and containers, with strong adaptability.

② Self unloading dry bulk carrier: it is a transport vessel with special cargo hold structure and equipped with a set of automatic unloading system. The use of automatic unloading equipment for self unloading dry bulk carriers increases the cost and weight of the ship. Therefore, it is necessary to improve the unloading efficiency to reduce the unloading fee and accelerate the turnover of the ship, so as to obtain good economic benefits. It is applicable to the route with short voyage and poor equipment at the unloading port.

③ Shallow draught large-scale ship: it is a new type of ship emerging in the process of ship type development to large-scale. Compared with ordinary cargo ships, it increases the ship width under the condition of constant draft, and adopts the method of large wide draught ratio to increase the deadweight, so as to greatly improve the economy of the ship. It is mainly applicable to the waters with limited water depth in ports and channels, and is also the preferred ship type for the development of river sea intermodal transport.