Abstract: The present invention provides a service buoy for performing direct wireline maintenance of a subsea well. The buoy is maintained in position over the well by a rigid riser kept under tension and which allows for the well re-entry. The primary buoyant body of the buoy is maintained permanently submerged and a truss structure presenting the minimum surface area to the action of wind and waves extends above the sea level to support a small deck from which the wireline work can be performed. The centers of gravity and buoyancy for the buoy are in close proximity so as to minimize lateral surge and sway motions of the installed buoy.