In the early hours, who would be the first person to light a flame? THE COOK!
This was an ongoing propane leak that consumed the boat, especially the lower bunk area.
The cook turns on the flame, then FLASH FIRE consumes boat IMMEDIATELY leading to propane tank EXPLOSION killing the cook INSTANTLY.
The sleepers were probably already unconscious from breathing propane gas, then burned alive and/or smoke inhalation and/or drowned.
Are you even reading this thread?