While a mainstream view for these disappearances is that they were due to poor sailing, Arikiyo SAEKI says that it was due to the fact the boats got larger and Haruyuki TONO argues that it was due to the diplomatic conditions of the missions to Tang China.
この原因を航海技術が未熟であったためとする見方が主流であるが、佐伯有清は遣唐使船の大型化、東野治之は遣唐使の外交的条件を挙げている。