manage to do it

In the cabin you see something similar to what you've seen in useless cars. It seem to be used for turning, but you need something that makes you go ahead. The solution is in a lever next to it
The boat starts moving as you move it but soon it tries to but seems unable. It's Lois who informs you
"We're tied"
After getging the lever in the quiet possition you go look at it and see the rope is in a bad state but still resist... So you run the dock and look for something to use.
Finally you grab an axe with what once inside you cut it
Back in the cabin you move again