I really enjoyed this chapter. I thought the writing was clear and straightforward, and the events were described in a very captivating way.
I thought the way you depicted the genderless nature of the skipper was cleverly and seamlessly done; where the avoidance of male/female pronouns could have been clumsy or contrived it never was. In fact the only time I noticed it was the first 'they'... and that's fine because if I hadn't been pre-warned by your introduction that would have det up quite a nice question in my mind which, of course, your really very good last line would have answered.
I think the concept is excellent, with lots of potential, and it has particular force at this time, when trans and non-binary people are facing many similar issues and struggles to those that gay people faced thirty or forty years ago, having to deal with the same sorts of resistance, and beginning to have their voices finally heard. Sensitively handled, I think this could be a powerful story indeed.
I thought there were a few moments when the action could be a bit more clearly described; I had to read the passage depicting Regender's struggle with the skipper and his final escape a couple of times to get a sense of exactly what was happening, and even then I couldn't quite visualise the sequence of events fully.
I also thought that the chapter could be made stronger through some judicious pruning of redundant adjectives and adverbs, and just general tightening up where the sense is implicit without needing the extra detail. We know that sea water will be 'salty' and we probabaly assume it will be 'icy' too.. we probably don't need to be told!
Somewhat hypocritically, since it's advice that I always deservedly get when I post my own work for critique here(!) I think the chapter would also benefit from a bit more focus on Regender's inner world. The descriptions of his actions and responses are very well drawn, but we don't get much insight into his feelings - fear, anger, excitement, relief. When we do, it's generally through being 'told' what his thoughts are by the author - 'he thought', 'he felt' and so on. This can be a bit distancing. If you can find some points when his emotional responses are shown to us directly through his actions that would help bring us closer to him and carry us along with him even more.
A terrific start, though, and a wonderful final moment to springboard us into the next chapter!
Although I'm not a YA expert by any means, I think that Rebecca's estimate of 13+ for the target audience's age seems right. Certainly the language used suggests that sort of age, and your potential audience will have an intellectual understanding of the theme and subject matter as well as an emotional reaction to it. This doesn't necessarily mean the book is a YA novel per se though. Or so I imagine. Others with more experience in the arcane art of genre definition will probably be able to advise you better than me on that!