40 
Annex 1 
Qualitative 
Offshore Wind 
Turbine/ Ship 
Environment 
Safety 
Not significant 
Offshore wind turbine 
can continue to be oper 
ated (if necessary follow 
ing extensive repair) 
No or minor environ 
mental pollution 
No injuries 
Considerable 
Offshore wind turbine 
defective 
Considerable envi 
ronmental pollution: 
Service products from 
side tanks*/ double 
floors flow into the 
water (double hull and 
double floors not fully 
penetrated) 
Few injuries 
Serious 
Offshore wind turbine 
destroyed 
Major environmental 
pollution: Loading 
tanks leaking, leak 
age of content (double 
hull/floor fully pen 
etrated) 
Serious injuries, 
small number of 
fatalities 
Catastrophic 
Nacelle or large parts of 
the nacelle crash down 
on the vessel 
Ship breaks apart/ 
sinks 
Large number of 
fatalities 
* Normally, ballast water is carried in the side tanks 
Table 5: Consequences 
3) Determining the frequency of occurrence of various scenarios: 
The probability of occurrence of the scenarios identified in step 2 should be determined using error 
tree analyses and model calculations. 
4) Collision calculation: 
The mechanical estimation of collision safety (consequence analysis) can be calculated using sui 
table simulation programmes. These include FE programmes with an explicit solution algorithm for 
dynamic questions, e.g. LS-Dyna, MSC.Dytran, Abaqus Explicit, Pam Crash to name only a few. 
Furthermore, processes have been developed for evaluating the collision safety of offshore plat 
forms that are based on yield hinge theory. These are implemented, for example, in the USFOS 
calculation programme. The selection of calculation method is left to discretion. Proof of applicability 
is to be provided. 
In connection with a risk analysis, it should be demonstrated that there will be no major environmental 
pollution incidents because 
a) either the entire collision energy can be absorbed by the ship and the offshore wind farm structure 
or 
b) the offshore wind farm fails during the collision procedure without ripping open the ship's hull. 
The following general conditions shall to be met: 
1) When using a simulation, the offshore wind turbine is to be idealised in a suitable way for a contact 
problem (shell elements when using FE method). 
2) The offshore wind turbine structure is to be represented at least up to the deck height of the ship 
plus 5 m, as shown in point (1). The masses and the inertias of the parts further above (tower, 
nacelle, rotor, etc.) shall also be considered.