We learn in a clarifying Brisa that crying out for human help on Shabbas for a ship floundering at sea and other immanent dangers is acceptable, according to Rav Yosi.
He holds that calling out to G-d, is not allowed because of the uncertainty of the response marring the sanctity of the Sabbas. Rashi clarifies that Rav Yosi is referring to a dramatic public prayer. It is not the Jewish customer to morn publicly on Shabbas so this thinking is consistent. Private prayer is acceptable.