Maritime Industry Network
Home > Resources > Mariner's Formulae > SWL, MSL and Breaking Strain
 
Mariner's Formulae Quick reference guide
SWL, MSL and Breaking Strain
 
BREAKING STRAIN
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


MAXIMUM SECURING LOAD (MSL)

MaterialMSL
Shackles, rings, deck eyes, turnbuckles made of mild steel50% of Breaking Strength
Fibre rope33% 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 steel50% of Breaking Strength
Chains made of high tensile steel33% 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.
To Top