Some beam tracks can only use metric fastners; see table for details.
The moment of inertia is used to calculate the stiffness of material
section. All track is extruded from Aluminium 6082T6.
Beam track is
available from size 0 to 3 and is used when spanning cockpits and
across companion way hatches. Three fixing bolts should always be
used either side of the span and washers fitted under the head of the
bolt and between track and deck.