Ross and Chandler just can't handle a strong independent woman ! In the last episode - Riley didn't disrespect anyone, she just questioned Chandler's dubious actions, and he saw that as a major sign of disrespect. She did it in a loud drunken way, but there was no hostility or disrespect. I bet if it were a guy questioning him, he wouldn't have taken offence.
Also on the caves trip, Ross was very panicked. As Riley said, even if you are worried, you don't show it to the guests. He also chastised her for talking to the guests as though that was not her place. So since when are third deckhands not allowed to talk to guests ! Then he couldn't trust her to do her job and left the wheel in rough seas. And if that weren't enough, once back on the main boat, he takes his insecurity out on her telling her not to question him etc.
Even Ashton has got in on the belittling of Riley. She was asking him what to do etc and he snapped at her for asking for clarification. Then once again blamed her for him loosing his cool.
She is the novice on a yacht so needs to ask questions and have things clarified. They just get annoyed at this and belittle her at every opportunity. She has no option but to talk over them as they don't listen to her. You can see Chandler's disrespect for women as he ignores Caroline's request for help in a very rude manner.
Riley has more gumption than any of the male deck crew. I doubt they would survive on an Alaskan fishing vessel !