This study determined the ship replacement life expectancy from an economic perspective. There are many ambiguities in the cost for calculation of economic lifespan, and these were expressed as fuzzy numbers. Also, a fuzzy cost model using fuzzy numbers was developed and suggested as a more practical analysis method than the existing cost model. And the suggested fuzzy model was used to determine the economic lifespan for various types of container ships. As the result, Without fuzziness, the economic lifespan of 5000 TEU Ships was found to be 19 years. it was found that the greater the container ship, the greater the economic lifespan was.