I agree with the fact that CW faced heavy odds pursuing a Naval career. But I was inclined to think that he had no other career alternatives. Well, there's the curate which his brother might be able to help him get into. But it might not be adventurous nor sufficient enough to support a baron's daughter. The riskier option would be to piggyback on his uncle's Naval connections, and hope for the best. I suppose he could have thought that if he perished, then so be it :-)