I wonder why no-one even considers that the technology may have gone from east to west?
At Empire's Edge:Pliny the Elder also added a warning: "The subject is one well worthy of our notice, seeing that in no year does India drain us of less than 550,000,000 sesterces giving back her own wares, which are sold among us at fully 100 percent their first cost." Romans were not the only ones to comment on the nature of their trade with India. A Tamil poem from the second or third century A.D. includes the following passage: "The beautiful vessels, the masterpieces of the Yavanas [Westerners], stir white foam on the Periyar, river of Kerala, arriving with gold and departing with pepper." Despite the discovery in southern India of some six thousand silver denarii and gold aurei, which seems to corroborate these statements, scholars disagree about whether such an economic imbalance actually occurred. Certainly the Romans spent vast sums of money on Asian luxuries, but they might also have used a barter system. Roman amphora, pottery, glass, lamps, and other items have been excavated in India, Sri Lanka, and Arabia, and Roman beads (gold or silver, set in glass) have been uncovered in the Rufiji Delta of Tanzania... In addition, the Greek/Egyptian author of Periplus Maris Erythraei (Circumnavigation of the Red Sea) identifies specific places where bartering was or was not possible. [pp 88-89]
Exploring Rome's Egyptian Frontier
by Robert B. Jackson
Roman period maritime artefactsDozens of classical wrecks excavated in the Mediterranean have produced a clear development of hull construction although little is preserved of their rigging. With no wrecks excavated in the Erythraean Sea the vehicles of the Roman trade are not represented in the archaeological record. Papyrological records detailing receipts and trading activity on the Nile mention Greek vessels called hellenikon, large river vessels which sailed the Nile (Lewis 1983: 143; Bagnall 1983: 35). These records give some detail of the rig, which may have been utilised on the Red Sea, this includes linen sails, ‘rings’ and blocks. As ancient sources suggest (Herodotus 2.36) Egyptian type vessels were quite different from specifically sea-going vessels, although a range of technologies may have been utilised by the Romans. However there is no published archaeological evidence for the type of craft referred to as ‘the good vessels, masterpieces of the Yavanas (westerners)’ (Sidebotham 1986: 23) mentioned in the c. 150 AD Tamil poetry of the Kauliliya Arthasastra. This referred to the arrival of Yavanas to the Malbar coast port of Muziris.
Univ of Southampton
2001
Long before the Romans hit the water, the Etruscans were coastal pirates, and the Phoenicians were going on the open sea. At that time the trade between Egypt/Somalia and India was extensive, and that is open ocean sailing. By the time the Romans began sailing the Red Sea and the Persian Gulf they would have found excellent boatmakers locally. It is very possible the Romans brought some boatbuilding technique back from the East.