Commentary Par XI 118-123

Now our archimandrita, Francis ([Par XI 99]) is placed in relation to Thomas, a patrïarca.  It is probably not accidental that Peter, referred to as archimandrita in Monarchia (see C.Par.XI.99), is mentioned here, as Dante obviously sees the first archimandrita and the second (Francis), as well as the new patrïarca (Dominic), as all playing a major role in the shaping of the Church, past and present, when the weakness and corruption in the papacy made the mendicant orders especially necessary in his eyes.

The whole metaphorical passage is developed in nautical terms, in which Peter is the first captain, followed by Francis and Dominic as co-captains, of the Church.  She is portrayed as a merchant ship (surprisingly, perhaps, until one thinks of the commercial metaphors that are present in some of Jesus' parables), with a precious cargo in its hold, the true believers who (we must assume) will be numbered among the saved.