When creating a model of a particular structure for the first time, you should resist the temptation to being with a model which incorporates full complexity. Better practice would be to create a relatively simplistic model initially, and to gradually introduce complexity once you are entirely satisfied with the basic model. It is generally advisable to examine some key outputs from the initial static analysis first – it may be possible to verify these using some simple hand calculations. For example, the maximum effective tension at the top of a riser should be roughly consistent with the (wet) weight of riser suspended below it. As you examine various load cases (e.g. vessel offset, current etc.), make sure you understand the structural response and you are satisfied it makes sense intuitively.
