Roman warship from the Fortuna temple relief in Praeneste

[Tarbicus]

But what are the three lances representing that seem to come out of the structure mentioned before and point straightforward, one with some kind of a disc at the shank? Do we see here the tip of a ballista or of the harpoon-like harpago? Any ideas?

Could be pila, the one in the middle weighted? But I could be very very wrong, and it's an interesting suggestion which would make sense.

Another Question: there are shown only two rows of rudders and two men of the Roman marine infantry are standing on a box that shows something like rudder blades. Do You think that here really is shown how the oars are drawn in?

The problem with that is the number of 'slots' doesn't match the number or pattern of the two rows of oars below them. I personally think it's a decorative ledge for the marines and sailors to stand and maneouvre on. Note a similar decorative effect running up the prow at the left, although smaller in size.