Europe’s inland waterway transport sector must decarbonize by 2050, creating urgent demand for sustainable fleet retrofitting. This study using interviews, surveys, field visits, and capacity analysis found most suitable shipyards are clustered in the Netherlands and Belgium. To meet targets, 36–54 mid-sized shipyards must work year-round on retrofits and new builds, but current capacity may fall short due to unknowns like workload and future demand. Of 57 identified shipyards, many may lack the scale required. Closing this gap will require new facilities, standardized retrofitting methods, EU policy support, and subsidies. Without coordinated action, decarbonization goals are at risk.