Very Large Floating Structures (VLFS) have drawn considerable attention recently due to their potential significancein the exploitation of ocean resources and in the utilization of ocean space. Efficient and accurate estimation of theirhydroelastic responses to waves is very important for the design. Recently, an efficient numerical algorithm was developedby Ertekin and Kim (1999). However, in their analysis, the linear Level I Green-Naghdi (GN) theory is employed todescribe fluid dynamics instead of the conventional linear wave (LW) theory of finite water depth. They claimed that thislinear level I GN theory provided better predictions of the hydroelastic responses of VLFS than the linear wave theory. Inthis paper, a detailed derivation is given in the conventional linear wave theory framework with the same quantity as usedin the linear level I GN theory framework. This allows a critical comparison between the linear wave theory and the linearlevel I GN theory. It is found that the linear level I GN theory can be regarded as an approximation to the linear wavetheory of finite water depth. The consequences of the differences between these two theories in the predicted hydroelasticresponses are studied quantitatively. And it is found that the linear level I GN theory is not superior to the linear wavetheory. Finally, various factors affecting the hydroelastic response of VLFS are studied with the implemented algorithm.