A shading device of a water vehicle, having a roller blind web, a winding unit, onto which the roller blind web can be wound or unwound and which, in relation to a longitudinal center plane of the roller blind web, is borne on both sides so as to be rotatable, and comprising, in relation to the longitudinal center plane of the roller blind web on each of its two sides, a telescopic tube arrangement having a bearing tube that is fixed relative to the vehicle and having at least one first pull-out tube and one second pull-out tube, which are displaceable between a slid-in position, the roller blind web having been wound up onto the winding unit when being in said position, and a pulled-out position, the roller blind web having been unwound from the winding unit when being in said position.