For Manilla, Breaking Strain = Circumference² [tonnes]
                                                   2.5

For Wire, Breaking Strain = Circumference² x 2.5 [tonnes]

SAFE WORKING LOAD

SWL   =   Breaking Strength
                  Safety Factor

Material	MSL
Shackles, rings, deck eyes, turnbuckles made of mild steel	50% of Breaking Strength
Fibre rope	33% of Breaking Strength
Wire rope (single use)	80% of Breaking Strength
Wire rope (re-useable)	30% of Breaking Strength
Steel band (single use)	70% of Breaking Strength
Chains made of mild steel	50% of Breaking Strength
Chains made of high tensile steel	33% of Breaking Strength

In a combination of securing gear with different MSL for lashing, the overall lashing strength would equal the weakest link used, i.e. the gear with the smallest MSL.