Skellig is internalizing many of his thoughts and feelings on the matter at hand, simply because it is easier to keep a neutral outward expression and demeanor if he pushes the rest of things aside to deal with later.

(It may not be the healthiest way of doing things, but in this scenario and situation, it is what needs to be done.)

As the sun nears the low point on the horizon, the few faint clouds begin to shift, changing to pinks and purples; Skellig finds himself near the stern of the ship, studying the clouds (he is still listening, always listening; the discussion has shifted to dinner for the crew, and the young man from earlier is also tasked with feeding the slaves below deck their rations for the night) and the winds aloft as they catch the sails. He is tired, from having to do so much work with his mind and ears, but he will not let his guard down - which is why he hears her as she approaches him from where she has been perched most recently.