Crankshaft for reciprocating engine

A crankshaft for a reciprocating engine, the crankshaft configured to be mounted in a reciprocating engine, the crankshaft comprising:

• journals that define a central axis of rotation;
• crank pins that are eccentric with respect to the journals;
• and
• crank arms, each of the crank arms connecting a corresponding one of the journals to a corresponding one of the crank pins,
• wherein each of the crank arms or at least one of the crank arms integrally includes a counterweight, and
• wherein the crank arms have a recess in a surface adjacent to the corresponding one of the journals, the recess disposed inward of a peripheral region along a periphery of the surface, the recess disposed along the peripheral region, so that, in the crank arm, a central region inward of the recess is thick.