Lashing Optimisation
Significant lashing loads can be imparted to a helicopter in high sea states.
Using the OnDeck code AVT can simulate the effects of various types of lashing schemes and lashing types. Sensitivity plots can be produced to assess scheme robustness and how susceptible the scheme is to catastrophic failure. Through this process a lashing scheme can be tailored to maximise sea state capability.
Although helicopter manufactures often recommend a scheme, in practice it can be very difficult to achieve due to limited deck tie down points or hangar space. AVT have conducte lashing analysis for a range of helicopter types including Black Hawk, Sea King, Lynx and MRH90.
A poorly laid out chain lashing scheme can cause particular problems because of poor load sharing. Further difficulties can arise due to the requirement to maintain adequate clearance between lashings and airframe fittings. Shown above is a Constrained Tie Down Optimisation Envelope for Black Hawk Lashing Scheme
Ondeck can be coupled with various constrained optimisation codes or a monte-carlo batch process to assess the performance of a lashing scheme over a range ship motion input. The likely number of failure events per hour can also be estimated for a particular condition.
Shown at right is a Sensitivity plot of a Particular Lashings showing rate of change of loading with lashing placement
