If lifebuoys are required, make sure they are approved, readily accessible, attached to a buoyant heaving line, have no tears of perforations, and have good working grab lines. There are two sizes. They should have an outside diameter of either: 610 mm. a small vessel lifebuoy, (these approved by Transport Canada) or 762 mm. a SOLAS lifebuoy, (these approved by SOLAS).