If you go to a modern shipyard, you will see the shipwrights contriving his ship with a way that is used in the Mediterannean the last 1500 years. That is, placing it's keel levelly to the ground and connecting it with the stern. He stabilises them in standing position with abutments. Afterwards, he places the occupants, the stemsons beginning from the middle of the hull. In a few days or weeks, having to do with the size of the ship, a shell will appear in the dockyard. In this skeleton, where the shape of the ship is already predesignated, the straight beams of the skinning will be sprigged, if everyone bends during its placement. This is a scene that was never seen by any visitor of the ancient shipyard.
All the shipbuildings of the greek ships, but also of the other nations of the Mediterannean, with no exception, were realized with a totally different way: firstly the skinning was completed and then the stemsons were placed. This method is known with the english term "shell-first". Our ancestors of the geometric ages (800-700 BC) constructed the ships according to the above way
They were placing the keel levelly on the ground of the shipyard, which was made by one or two trunks, relevant to the length of the ship. This keel, the "tropis", was bended and not straight, as it is today. The fore and the aft were connected with two sterns. In the upper part of the keel, they were opening parallelogram holes of a few centimeters, able to take a "wooden tonque", "morso". A beam hewn with an adz, with the same holes as "tropis", was placed in such a way, as the part of the "morso" that stood out would be steadied onto the keel. Every "morso" was locking with the impaction of two dowel pins (rivets).
So, left and right of the tropis, there was the first row of beams. It was following, connected with the same way, the second row, the third row, until the hull was completed and the gunwale was next. Only then, the shipwright was placing within the "skarmos", toed with big brazen pins from the outside to the inside.
In order to avoid the corrosion of the wood from the water microorganisms, if the ship hadn't been used for some time, it was pulled up to the land. The housing establishment of the pulled up ships were called "neosoikoi" ( Greek: νεώσοικοι, shipyards/dockyards ) and we have found ruins of them in many ancient ports. It is said that there were 372 dockyards in the port of Peiraias. The "neoria", where the warships were housed, when they were not in action, hide many secrets of the shipbuilding art of the ancient Greeks. It seems that most dockyards had six meters width. Neoria were lengthy buildings with a slopping roof and a normal aptitude to the sea, usually chiseled in the rocks. The length was from 21 to 47 meters, relevant to the length of the ships. We have many examples of this, in Peiraias, in Rhodos, in Thasos, in Honiades, in Carchedona, while important remains have been found recently in the Kition of Cyprus, and in Marseille, while some of them were discovered during excavations in Naxos (Sicily).