## 1 Introduction
The determination of the electric field is mainly conducted through computational models, such as finite elements [7, 8, 15, 16, 17, 18, 19], the hemispioroidal model [16, 20, 21], finite volume elements [16, 20, 21], the inclined layer model [16], cross-platform finite element analysis, solver and multi-physics simulation (COMSOL) [4], and semi-analytical methods based on the complex images method with specialised interpolators (generalised pencil of functions) [19, 22]. The above are usually based on the knowledge of the soil/sea resistivity throughout the area under study, which is obtained through geophysical-petrophysical-electric methods [5, 6, 7, 15], such as magnetotelluric and electrical resistivity tomography [23, 24], drillings, electric potential measurements in sea, electric soundings, and transient electromagnetic soundings [25], which are very costly and time-consuming to implement. Additionally, the acquisition of specialised software packages for the determination of field analyses (such as COMSOL [4] and CDEGS [12, 13]), the training in them, and the respective simulation are also costly and time-consuming. Alternatively, it is performed through approximative analytical methods based on Green functions for soil/sea layers and the method of images [26] or using point sources of electric current, as formulated in CIGRE B4.61 675:2017 [1] or through its variation in IEC TS 62344:2013 [27], where, in the first case, the homogeneous soil occupies a hemisphere, the water forms a wedge, and the air occupies the rest of the area, whilst in the second, the soil-air roles are reversed. The second case is based on the Rusk methodology [8; 28; 29; 30; 31], taking into account the electrode resistance and the electric current intensity in water and soil, while the Uhlmann method disregards the effect of the soil and seabed [8; 32]. In [2], the respective analytical methods of point current sources are unified. Furthermore, the addition of the breakwater to the analytical methods [1; 27], as well as the use of a linear current source (instead of a point source), with a cylindrical water zone of specific height, were also proposed to the study of the near-electric field. The latter proved, in the preliminary study, to be the most appropriate method for the analytical approach to the problem, which, in combination with the superposition method for the utilisation of many electrodes, gives easy and fast results for the study of the near-electric field (in the present case), for the electrode stations of Stachtoroi and Korakia, regarding the HVDC interconnection of Crete and Attica. In this paper, the preliminary study of shoreline pond electrode stations with electrode arrangements other than the typical one (where the vertical or inclined electrodes linearly placed form frames, and then the frames are placed linearly, parallel to the longitudinal axis of the breakwater) is carried out in order to address the space limitations of the specific locations (Stachtoroi and Korakia for the HVDC interconnection of Crete, Attica), covering the limits of the potential gradient for the protection of marine life and divers in marine electrodes in steady and transient states and of the absolute potential, in relation to remote earth, for the steady state. To calculate the electric field gradient, ground potential rise, and resistance to remote earth of electrode stations, the method proposed in [2] is used, which means that for the near-field, a linear current source is used for each electrode, which extends cylindrically in a sea/soil or dam zone of constant circumference. The respective mathematical background of a point current source, in the form of an appropriate wedge of sea on the ground, is used for the far-field (extension of [1; 27]). In the case of more than one electrode, the application of this method is extended through superposition.