Most early ships used both oar & sail (some used paddles rather than oars) but I’m not sure what you mean by pre-COG so can’t be much more specific than that. Part of the problem is that searches for ships of the pre-classical era (Trojan Wars, Mycenaean etc) often show galleys of the classical era because many people think they are the same.
Trading vessels were often multifunctional, used as warships or raiders/pirates as the need arose (or opportunity presented itself). Bulk traders would be broader in beam and would operate under sail whenever possible as their smaller crew made rowing hard work and slow. Pre-classical smaller ships might be 20-30 oars and crews of no more than 30-50 all told, larger ones not all that much larger with crews 60-100 and 40-50 oars.
I’ll see if I can find reasonable images on the ‘net but I tend to use books more than the net for that area of interest. I’m a bit snowed under at the moment but I’ll see if I can scan some stuff and e-mail it to you sometime over the weekend.
Tony of TTT