A mobile welding system that does not rely exclusively on a track to define the path of the welder. The present invention generally provides a mobile welder adapted to move along a work piece, the mobile welder including a chassis supporting a motor assembly; a travel assembly attached to the chassis and adapted to support the chassis over a portion of the work piece, wherein the motor is coupled to the travel assembly to selectively cause the chassis to move relative to the work piece; a controller connected to the motor assembly to control movement of the chassis relative to the work piece; a chassis holder connected to the chassis, the chassis holder being adapted to provide a force holding the chassis a selected distance from the work piece; and a welder supported on the chassis, the welder including an implement adapted to perform a welding operation, wherein the implement is supported on the chassis at a location where the implement and the chassis define an uninterrupted line of sight from the implement to the work piece, wherein the chassis holder is spaced from the line of sight a distance sufficient to prevent the chassis holder from interfering with the welding operation.