The invention relates to a boat or ship's hull comprising a composite material with an electrically conductive reinforcement. The hull, preferably of reinforced plastic, is arranged with predetermined properties in respect of shielding against electromagnetic radiation and possibly radar reflection. The hull is formed with hatches which can be closed by means of e.g. covers and doors, provided with electrically conductive seats in respect of the radiation leakage round the hatches. The invention also concerns a method of fastening the seals.
PRIOR-ART TECHNIQUE
Modern warships have to an increasing extent hulls that are built in consideration of radar reflection and shielding against electromagnetic radiation. The former can be intended to direct the radar reflection. The latter can be intended to reduce the emission of revealing signals and to protect the equipment from electronic radiation from outside. On ships with a hull made of a composite material, e.g. a plastic hull, this has been carried out according to prior art by providing the outside of the hull with an electrically conductive layer of e.g. glass fibres, whose surfaces have been coated with a conductive material, e.g. aluminium, in these hulls, aluminium covers contained in aluminium frames are fastened. The seals between the frames and the covers are designed according to prior-art technique for seals between metal parts. A putty containing metal particles has been used between the hull and the frames to obtain a satisfactory electric seal and a connection between the frames and the layer, said connection being unbroken along the fastening of the frames. For, inter alia, the putty to obtain sufficient conductive properties, metal particles of silver have been used. The thus achieved composition of metals, which from the viewpoint of the chain of stress is poor, has been devastating. The aluminium surfaces which have been in contact with the putty, i.e. surfaces of the frames and the fibres of the layer, have corroded significantly, which has caused the connections between the surfaces to be cut off, resulting in leaks in the shielding and great costs of repair and maintenance. This technique also suffers from the drawback that the shielding has not been satisfactory also because of disconnection caused by temperature stress, and therefore it has been necessary to shield much equipment in the ships individually. As a result, the manufacture and maintenance of the ships have become expensive.