Roman shipbuilding and navigation

Complete the summary. Write ONE WORD ONLY  from the text in each gap. 

Warships and merchant ships

Warships were designed so that they were 6. and moved quickly. They often remained afloat after battles and were able to sail close to land as they lacked any additional weight. A battering ram made of 7. was included in the design for attacking and damaging the timber and oars of enemy ships. Warships, such as the ‘trireme’, had rowers on three different 8. .

Unlike warships, merchant ships had a broad 9. that lay far below the surface of the sea. Merchant ships were steered through the water with the help of large rudders and a tiller bar. They had both square and 10. sails. On merchant ships and warships, 11. was used to ensure rowers moved their oars in and out of the water at the same time.

Quantities of agricultural goods such as 12. were transported by merchant ships to two main ports in Italy. The ships were pulled to the shore by 13. . When the weather was clear and they could see islands or land, sailors used landmarks that they knew to help them navigate their route.