A juanga or joanga refers to large-sized kora-kora, karakoa and lanong. They are used all throughout the Philippines and Eastern Indonesia, in Maluku smaller versions were popular and are still used to this day (Kora-kora). They are propelled by oars but are not used for carrying cargo.

The word juanga and joanga are cognates with "junk", which refers to several types of ships in Asia. Retana and Pastells considered the name derived from Hokkien Chinese: 船; Pe̍h-ōe-jī: chûn, which means boat. Paul Pelliot and Waruno Mahdi reject the Chinese origin of the word "junk". Instead, it may be derived from "jong" (transliterated as joṅ) in Old Javanese which means ship. The first record of Old Javanese jong comes from an inscription in Bali dating to the 11th century CE. It was first recorded in the Malay and Chinese language by the 15th century, when a Chinese word list identified it as a Malay term for ship, thus practically excludes the Chinese origin of the word. According to William Henry Scott the term "joanga" came from "jong", a large Southeast Asian ship.

According to a manuscript probably made by António Galvão ca. 1544 the ship was made in this way: The shape in the middle of the ship resembles an egg (he ovedo no meio) and the ends curl upwards. Thus, the ship can sail forward and backward. These vessels were not nailed or caulked. The keel of the ribs, as well as the front and rear height are adjusted and painted with fibers (guamuto, in the local language gomuto) through holes made in certain places. On the inside there is a protruding part in the form of a ring for inserting the strap so that it is not visible from the outside at all. To connect the boards, they use a pen on the other end of the board to make a small hole to insert the pen. Before joining these boards, they were given a pen to keep water from entering: spliced together, the boards were sandwiched so that it looked as if they were standing from one blade only. In the bow is inserted "wood (carved) in the form of a snake with a dragon's head with horns like a deer".

When the ship is finished, ten or twelve well-worked beams are laid across from the hull to the hull. These beams are called ngaju, serve as supports as in galleys, placed carefully until it doesn't wobble anymore. This ngaju protruded from the sides of 1, 2, or 3 braca (1 braca is about 0.3043 meters) according to the size of the ship. Above this ngaju, parallel to the ship, were tied two or three rows of bamboo, called a cangalha. In this place the rowers sit (so on the water), separated from the other rowers who are in the space of the ship. At the very end of this ngaju there are several branches. Called the pagu, as a place to tie other bamboos that are bigger and longer, this bamboo is given the name samsah (semah-semah, the local name for outriggers), to support the ship when it rolls.

In the ngaju part of the ship, a floor of split rattan, a kind of upper level or deck, is made, which is called baileo. If they ever wanted to do evil to the people who sailed on it, namely those who were armed, they could sweep the baileo with their ngaju; and the soldier fell into the water and drowned. In baileo, booths such as the toldo and conves were made, that is, a section on Portuguese ships used to be specifically for officers and dignitaries. The kolano (kings of northern Maluku) occupy it whilst lying or sitting on halls, and beside it was a place for captains, ministers and armed soldiers. They are called "baileo people". Above these booths are covered with mats, called kakoya, from the bow to the stern like a tent in a galley (como temdas de geuale) for shelter from the hot sun and rain. The kolano along with their siblings and the sangaji used a tent made of white kakoya and are called papajangga, which are rectangular. At each corner of this tent flew a flag made of feathers like the tail of a chicken, moreover there were two other flags in front almost as high as sea level, one each on the left and right, made of red cloth "which are not rectangular but resembled a tongue". The king's flag was raised from the mast in the middle of the ship.

While the king and the captains with the minister sailed on the baileo, their young sons stayed below, the others sat in the cangalha rowing. When these sons were promoted, they were ordered to go up to Baileo and did not have to row anymore. This is a great honor for them. If they are not meritorious, they may not use the sword or be given a promotion, which is the same price as being awarded a title. From the cangalha they were put on board, and this too was an honor. Then, if they are meritorious, they were put on baileo again and abandon the oar. The paddle is very well carved, light, and shaped as an iron spearhead, sometimes round. The stalk is one covado (± 20 inches, 50.8 cm), the head is a small cross (huma cruzeta peqeuna) as a handle, while the left hand holds the leaf. The oars are free (not tied). And they are called pamguayo (pengayuh—rowers). The wood is also used as a dinner plate and a place to cut any item (servem de comer neles e d'al qualquer cousa em hum trimcho). The sails are made of burlap or from mats.

According to the same manuscript, in Maluku there are many types of ships, the most important of which is called the juanga, which resembles a royal galley (guales reaes). There are also other ships called lakafuru, kora-kora, kalulus, and small boats. Each of them is driven by oars and is not used for carrying loads, the space is long but not deep, a juanga can carry 200 oars per hull side, plus nearly 100 baileo men (e mais perto de cemhomens de baileu). However, there are also smaller juanga carrying only 150 paddlers per side and 50 people on Balieo, some are even smaller. Usually juanga, lakafuru, and kora-kora carried 1–3 boats, but in case of danger these boats may be discarded onto the sea.

The Spanish priest Francisco Combés described karakoa in great detail in 1667. He was also impressed by the speed and craftsmanship of the vessels, remarking: