Merchant ships eventually were armed and double decked. The upper deck offered some protection from pirate or enemy missiles and also increased cargo capacity. Merchant ships carried rostra, but usually not of the size or strength of those on the warships. The Phoenicians were great innovators in ship design, but their ships were soon copied (or in the case of the Romans, copied much later).
This is a boat illustrating how the Greeks traveled to places like Asia Minor, Egypt, the islands of the Mediterranean Sea and the Aegean seas. They used boats like this for many purposes like war, shipping, or traveling, as it states in the book.