Potential transmissibility of asymptomatic 2019 Novel Coronavirus infection and a substantial asymptomatic ratio have been reported in clinical studies. Employing a statistical modeling analysis, we derived a delay-adjusted asymptomatic ratio of the positive 2019-nCoV infections onboard the Princess Cruises ship along with the timeline of infections. We estimated the percentage of cases that are asymptomatic to be 34.6% (95% CrI: 29.4%-39.8%), with most of the infections occurring before the start of the 2-week quarantine.