With the emphasis on "approximately", aluminum has 60% of the strength
of steel. Algebra: 0.60 / 1.0 = 0.375 / x and x = 0.625 or 5/8"
Good luck,
Boatdreams

Techie wrote:

If a plan for a ship calls for 3/8" thickness in steel hull, what would
that be app. in Aluminium instead?