I'm trying to denote a stutter while this person is freezing her ass off. Does this work well enough? “Hold on. I need t-t-to no-notify an mergency crew.” She closed their connection and called the control center. After her call, she said, “I’m s-s-so s-s-s-sorry Admiral, that riftia t-t-t-t-tube should not have done that.” She shivered uncontrollably.
This may just be a preference, but I think it would work better if the stuttered word was closer to the beginning of the sentence ('need' instead of 'to') because she'd be fighting the cold more at the moment she's trying to get her mouth working.