Silence means assent, so Wellard pulls out a knife and grabs one of the marlinspikes (http://en.wikipedia.org/wiki/Marlinspike) let by the coils of rope.

"A good section of the ropes got burned through by an explosion, so we're having to re-join some of the sections."

Wellard thus beings showing River how to splice (http://en.wikipedia.org/wiki/Rope_splicing) a couple shorter pieces of rope together.