This part of the story is told through multiple occasions where the brother of Jared comes to the Lord with questions. Apart from the story, the lesson is clearly that our changing circumstances in life will require our continued conversation with God, and our continuing to seek counsel from Him. We may receive information for the next steps, but those next steps may lead to more questions, and further reasons to rely upon the Lord.
In this case, the brother of Jared sees to the building of the barges. While they were to be similar to those built previously, they were also clearly different. The brother of Jared needed multiple instructions on how to make them functional.
In this conversation, there are multiple problems: how would they be lighted, steered, and how could the occupants breath in a sealed barge? These verses describe the solution to the breathing issue. The answer is that they should have a hole in the top and a hole in the bottom of the barge’s hull. While having holes in the hull is usually something to be avoided in a vessel, it is possible that these two holes were connected by a tube. (A modern-day engineer has suggested such a mechanism and has demonstrated how it might work.)