If I take hanniabu's numbers, that ends up with 8000 ft. zeppelins--the length of airport runways. That's probably not going to be operationally viable: going by the space the largest seaports take up today, you have space to berth only a few of them--maybe 5 at best--at the very largest of them. There's therefore going to be very poor operational flexibility for choosing routes, and with the sheer size and capacity, multi-destination itineraries are going to struggle with long dwell times to partially load/unload them.