B) THE SHIP DIRECTION
The marble ship goes up the river or comes down towards the mouth? There is not yet unanimous agreement between the scholars about the direction of the ship; the main justification to support the two thesis are the following:
The ship is oriented to NorthWest and is going up the river:
1- It is shown in this way in cartographic representations and period engravings, sometimes imaginative, as the drawing of Onofrio Panvinio on middle XVI century (pict.D3), the map of ancient Rome of Etienne Du Pérac (1574) (pict.D4) and the engraving of the same (1575), as well as that by Egidio (Gilles) Sadeler in 1606 (pict.D5) with the caption "...fu fatta detta isola a forma di una nave o galera come se ne vedeno anche oggidì vestigij quali si mostrano per l'infrascritti segni. A. era la platea dove era sopra fabricata detta nave B. la parte della poppa di esa...". Moreover the fantasy view by G.B. Piranesi, middle of XVIII century, (pict.B1) tha indicates as "stern" the represented extremity of the ship.
2- The ship is identified as the one that carried to Rome the snake of Esculapius, and therefore it goes up the river.
3- The prow intentionally was oriented against the stream as, ploughing through the water of the river, gives the illusion that the ship is moving.
The ship is oriented to SouthEast and is sailing towards the sea:
1- It is represented in this way in other period images as the maps ancient Rome of Ambrogio Brambilla (1582) (pict.D6) and Giacomo Lauro (1612) (pict.D7), the engraving of Nicolaus van Aelst (pict.D1) and the Giovanni Maggi one that at the beginning of '600 represented from upstream the stern of the ship (pict.B2).
2- For the message to Epidauro they sent a war-ship and the the still visible fragments of the ship exactly represent the prow of a roman war-ship (see the following section C) as also indicated in the above mentioned "Lexicon Topographicum".
[L'unico resto, ancora in situ sulla punta SE, è un frammento della prua, in peperino e travertino: sono raffigurati, a rilievo, Esculapio, il suo bastone con il serpente ed una testa di toro, probabilmente un elemento di ormeggio, a sinistra..] 
3- The monumental arrangement of the island does not refer to the ship of Esculapius, even if his symbols are carved on the ship, but is relevant to the celebration of the naval enterprises in the times of its construction (see the above section A) and therefore it was as a "manifest", symbol of the roman naval power, that welcomes people reaching Rome sailing back the Tiber.