The safety bulletin from the Marine Accident Investigation Branch (MAIB) said: "When they were not seen as expected the following morning, crewmen from fishing vessels tied up close by forced open the wheelhouse door.
"The gas grill was still lit and the wheelhouse was full of fumes.
The two men were dead in their bunks. Eshcol was not fitted with a carbon monoxide alarm."
The MAIB said carbon monoxide (CO) was a lethal gas that was difficult to detect and that crews needed to be vigilant to recognise the first signs of CO poisoning.
The bulletin went on: "Carbon monoxide alarms are not expensive and should be fitted."