HomeCalculatorsShaft Diameter (IACS UR M68)

Shaft Diameter (IACS UR M68)

Minimum intermediate shaft diameter per IACS UR M68 from rated power, rpm and material UTS.

StructuralIACS M68

Rated powerkWShaft rpm at rated powerrpmShaft material UTSN/mm²Installation k-factor–1.00 for single-engine direct drive; higher for twin engines or special configurations.

Intermediate shaft diameter

385mm

Tail shaft diameter (≥ 1.10 × inter.)

424mm

Formula, assumptions, and limits

UR M68 caps σ_UTS at 800 N/mm² for the formula; higher-strength materials need not reduce further. Tail-shaft diameter shall not be less than 1.10 × intermediate shaft.

Symbol legend

Meaning	Unit	Source
Rated shaft power	kW	engine/plant spec
Shaft rpm at rated power	rpm	engine/plant spec
Material ultimate tensile strength	N/mm²	material certificate
Installation factor	-	IACS UR M68
Shaft diameter	mm	result