Another consideration is the distinction between a "real" museum ship, and a ship replica. As repairs accumulate over time, less and less of the ship is of the original materials, and the lack of old parts (or even "appropriate" work tools) may lead to the use of modern "short-cuts" (such as welding a metal plate instead of riveting it, as would be the case during the ships' historical period). Visitors without historical background are also often unable to distinguish between a historical museum ship and a (more-or-less historically relevant) ship replica, which may serve solely as a tourist attraction.