When inserting the aluminium stringers, the boat needs to be flat. Place the oars under the length of the boat (it helps). Insert the stringer in the recess lip on the floor section. Normally on Zodiacs - there are a couple of rubber bump stops, that the stringer sits within. I used to wear wellies when building the boat - and the rubber heel was perfect for kicking the stringer into place. Alternatively, you could use a rubber mallet. Once the stringers locate, inflate the boat to full operating pressure. You'll hear a few clicks and grinds as everything is pulled together.