The weather is not cooperating for ship repairs. Particularly when the area you have been working on is up in the rigging. (It is one thing to go up there when needed- only a fool goes up there when he does not.)
Thus, Wellard is at a table, comparing things from a
book on the weather- the section on atmospheric layers, and a book on
early aviation.
Sextants, compasses, astrolabes- there more than likely is a way to measure air pressure and altitude that even he can understand- and even build. Hence the quiet mutterings as he takes notes on a piece of paper.