RedactedNarrative: Subject helped Operator rig his recently purchased sailboat.  They left Operator's home wearing PFD's and taking a hand held marine radio.  On the lake they noted the self-bailing was not working and there was water in the boat.  Operator tried to free the bailing plugs and the bow went under and the boat filled with water.  As trained, Subject and Operator stayed with the boat.  It was barely afloat stern up, but it sank away.  Subject called for help on channel 16 of his marine radio, as trained PAN PAN three (03) times.  He heard no answer.  He thought the time was 12:30 pm.  Operator was exhausted and losing hope and said he wanted to go to sleep.  Subject held him close and kept him awake until rescued by Charlevoix County Sheriff's boat.  Both were suffering from hypothermia.  Subject was treated and released from EMS.  Operator was transported to McLaren in Petoskey and was in ICU, but stable.