Who is "Rav ha'Chovel"?
Rashi: The captain of the sailors. Also they are called "Chovelei ha'Yam" (Yechezkel 27:29). Radak ? this is because they pull and untie Chavlei (the ropes of) the mast according to their Chachmah. Chovel is a general term for Chovelim. It is a noun; its grammatical form is like "v'Es ha'Yoser Hecheramnu" (Shmuel I, 15:15). Also Yonason translates like this. He conducts the boat; they pull and untie the Chavalim like he decides.
Why did he call to Yonah?
Malbim: All hope of natural salvation was lost. He thought that this strange storm came only on this boat due to a decree on the people of the boat. When all call to their gods the decree will be canceled. If one sleeps and does not call, the decree remains on him and the boat will sink due to him.
What is the question "Mah Lecha Nirdam"?
Rashi: Why are you sleeping? This is not a time to sleep!
What is the meaning of "Yis'ashes"?
Rashi: It is an expression of thought. The same applies to "Eshtonosav" (Tehilim 146:4), "u'Malka Ashis" (Daniel 6:4).
Radak: He will be appeased. The same applies to "Avdu Eshtonosav" ? thoughts of his desire. In Arame'ic, "u'Malka Ashis Lahakamuse" (Daniel 6:4).
Radak citing Targum Yonasan: He will have mercy.
Malbim: He will change His thoughts to a different thought and nullify the decree, and we will not perish.