A support structure for a wind turbine mast, comprising: - a seafastening ring comprising an annular inner wall and a connecting flange, wherein said connecting flange comprises a plurality of bolt holes and is configured to be secured to a corresponding connecting flange of the wind turbine mast by means of a plurality of bolts; - an auxiliary device, comprising - at least a support body received in the seafastening ring as to substantially overlap with the connecting flange of the seafastening ring in the vertical direction, the support body being provided with a plurality of bolt receiving positions aligned with the bolt holes of the connecting flange, and - moving means configured to move the support body in the vertical direction toward the connecting flange, such that a number of bolts arranged in the bolt receiving positions are collectively arranged through the bolt holes, said moving means comprising a first part connected to the support body, a second part connected to the inner wall of the seafastening ring, and means for moving the first part with respect to the second part under the influence of a mechanically, electrically, pneumatically and/or hydraulically generated force. - a seafastening ring comprising an annular inner wall and a connecting flange, wherein said connecting flange comprises a plurality of bolt holes and is configured to be secured to a corresponding connecting flange of the wind turbine mast by means of a plurality of bolts; - an auxiliary device, comprising - at least a support body received in the seafastening ring as to substantially overlap with the connecting flange of the seafastening ring in the vertical direction, the support body being provided with a plurality of bolt receiving positions aligned with the bolt holes of the connecting flange, and - moving means configured to move the support body in the vertical direction toward the connecting flange, such that a number of bolts arranged in the bolt receiving positions are collectively arranged through the bolt holes, said moving means comprising a first part connected to the support body, a second part connected to the inner wall of the seafastening ring, and means for moving the first part with respect to the second part under the influence of a mechanically, electrically, pneumatically and/or hydraulically generated force. - at least a support body received in the seafastening ring as to substantially overlap with the connecting flange of the seafastening ring in the vertical direction, the support body being provided with a plurality of bolt receiving positions aligned with the bolt holes of the connecting flange, and - moving means configured to move the support body in the vertical direction toward the connecting flange, such that a number of bolts arranged in the bolt receiving positions are collectively arranged through the bolt holes, said moving means comprising a first part connected to the support body, a second part connected to the inner wall of the seafastening ring, and means for moving the first part with respect to the second part under the influence of a mechanically, electrically, pneumatically and/or hydraulically generated force.