Question: Mao Kun map is often seen as a surviving document from the expeditions of the mariner whose ships could stretch past what length?

Context paragraphs:
Zheng He: Zheng He (1371–1433 or 1435), formerly romanized as Cheng Ho, was a Hui Chinese mariner, explorer, diplomat, fleet admiral, and court eunuch during China's early Ming dynasty.  He was originally born as Ma He in a Muslim Hui family, later adopted the conferred surname Zheng from Emperor Yongle.  Zheng commanded expeditionary voyages to Southeast Asia, South Asia, Western Asia, and East Africa from 1405 to 1433.  His larger ships stretched 120 meters or more in length.  These carried hundreds of sailors on four tiers of decks.

Pulau Beras: Pulau Beras is an island in western Sumatra, Indonesia.  It is described in Chinese explorer Zheng He's Mao Kun map.

Broadside: A broadside is the side of a ship, the battery of cannon on one side of a warship; or their coordinated fire in naval warfare.  From the 16th century until the early decades of the steamship, vessels had rows of guns set in each side of the hull.  Firing all guns on one side of the ship became known as a "broadside".  The cannons of 18th century men of war were accurate only at short range, and their penetrating power mediocre, entailing that the thick hulls of wooden ships could only be pierced at short ranges.  These wooden ships sailed closer and closer towards each other until cannon fire would be effective.  Each tried to be the first to fire a broadside, often giving one party a decisive headstart in the battle when it crippled the other ship.

Ping the Elastic Man: Ping the Elastic Man was a British gag-a-day comic strip series which originally appeared in the magazine "The Beano" in issue 1, dated 30 July 1938.  It was drawn by Hugh McNeill.  Ping was an elastic man who could stretch his body into absurd lengths.  The series ran in the magazine until 1940.

Mao Kun map: Mao Kun map, usually referred to in modern Chinese sources as Zheng He's Navigation Map (), is a set of navigation charts published in the Ming dynasty military treatise "Wubei Zhi".  The book was compiled by Mao Yuanyi in 1621 and published in 1628; the name of the map refers to his grandfather Mao Kun () from whose library the map is likely to have originated.  The map is often regarded as a surviving document from the expeditions of Zheng He in addition to accounts written by Zheng's officers, such as "Yingyai Shenglan" by Ma Huan, "Xingcha Shenglan" by Fei Xin, and "Xiyang Fanguo Zhi" by Gong Zhen.  It is the earliest Chinese map to give an adequate representation of Southern Asia, Persia, Arabia and East Africa.

Battle of La Guaira: The Battle of La Guaira or La Guayra, took place on 2 March 1743 in the Caribbean, off the coast of La Guaira, present day Venezuela.  La Guaira was a port of the Royal Gipuzkoan Company of Caracas, whose ships had rendered great assistance to the Spanish navy during War of Jenkins' Ear in carrying troops, arms, stores and ammunition from Spain to her colonies, and its destruction would be a severe blow both to the Company and the Spanish Government.  A British expeditionary fleet under Sir Charles Knowles was defeated, and the expedition ended in failure.  400 men were killed and wounded, among whom was the captain of the HMS "Burford", and many of the ships were badly damaged or lost.  Sir Charles was therefore unable to proceed to Puerto Cabello until he had refitted.

Penmachno Document: The Penmachno Document was a letters patent drawn up at Penmachno in Gwynedd and signed on 19 December 1294 by Madog ap Llywelyn at the height of his revolt against English rule in Wales.  Though unremarkable in its content – the document consists of the grant of two parcels of land to a minor noble named Bleddyn Fychan – its importance lies in the fact that it is the only surviving document issued by Madog in which he styles himself prince of Wales as well as lord of Snowdonia (this refers to the Welsh tradition that Snowdonia was the seat of power for previous Welsh princes).

Merchant Mariner Credential: The Merchant Mariner Credential (MMC) is a credential issued by the United States Coast Guard in accordance with guidelines of the International Convention on Standards of Training, Certification and Watchkeeping for Seafarers (STCW) to United States seafarers in order to show evidence of a mariner's qualifications.  It will become the standard documentation required for all crew members of U.S. ships with a Gross Register Tonnage of over 100 and for all vessels required to operate with a licensed Master, regardless of size.  As previously issued but still valid credentials expire, the MMC will replace the Merchant Mariner's Document, merchant mariner license, Certificate of Registry, and STCW Certificate.

Filips van Zuylen: Filips van Zuylen was a Dutch corsair active in the 1620s.  As part of the "Groot Desseyn" plan, he was particularly active against the Portuguese in West Africa but failed to capture the colony of Luanda, an important center for the Atlantic slave trade, in early 1624.  After this initial defeat he decided to wait for reinforcements from Brazil before making a second attempt, this time with fellow corsair Piet Heyn, in October of that same year.  While approaching from the south Heyn missed van Zuylen's 3-ship squadron, waiting to the north of Loanda, and decided to go ahead with the attack on his own.  Heyn's fleet suffered a disastrous defeat as a result.  Many of his ships became stuck in the shallows just outside Loanda and, when other ships stopped to free them, made easy targets for the Portuguese cannons.  Heyn quickly realized that his seven ships could not breach the colony's heavily defended fortifications.  Following a failed nighttime sortie against Portuguese merchant ships moored in the harbor, he ordered a withdrawal and the Dutch corsair fleet retreated back to friendly ports.

Polacca: A polacca (or "polacre") is a type of seventeenth-century sailing vessel, similar to the xebec.  The name is the feminine of "Polish" in the Italian language.  The polacca was frequently seen in the Mediterranean.  It had two or three single-pole masts, the three-masted vessels often with a lateen hoisted on the foremast (which was slanted forward to accommodate the large lateen yard) and a gaff or lateen on the mizzen mast.  The mainmast was square-rigged after the European style.  Special polaccas were used by Murat Reis, whose ships had lateen sails in front and Fore-and-aft rig behind.

Supporting paragraphs: Mao Kun map Zheng He
Answer: 120 meters