I would like to address two problems of the Jaredite's ocean voyage: drinking water, and space and feed for the animals.
First, potable water for humans and animals. The ocean voyage of the Jaredites lasted for 344 days-a long time to depend on a limited supply of water. It is unlikely that they were able to carry enough water with them to supply all their needs. Several possiblities suggest themselves. They could have stopped along the way and replenished their water supplies. This is unlikely as it is not mentioned in the text and they would have had difficulty getting back into the ocean currants that were carrying them to the New World.
Another possiblity would have been to use sea water. This is normally considered impossible as it is lethal over time. However, Thor Heyerdahl, during his voyage on the Kon Tiki, found that they could mix 40% sea water with their fresh water and use it with no ill effects. As long as the Jaredit's fresh water held out, they could have extended it in this way. It is also likely that being in the dark, humid environment that they were, they did not require as much water.
A third possiblity would have been to harvest the rainwater. The text mentions fierce and tempetuous weather during their voyage. There must have been many opportunities to harvest rainwater, but how? One possiblity comes to mind. The roofs of the barges must have been flat, slopping surfaces. If a slightly raised ridge had been constructed along the lower edge, it would have served as a gutter to catch the rainwater. They could have had periodic holes in the trough of this gutter which could have been opened at appropriate times to collect the rainwater.
There may have been other possiblities, but these are the ones that come to mind.
The other problem was space and food for the animals. The Jaredite experience was a mirror image of Noah's challenge, but with more people, more boats, and a longer voyage. Both groups had to plan for an extended time and provide enough food for man and animal. But the Jardites voyage was longer and thus required more provisions. One solution for both the Jaredites and Noah would have been to carefully select animals that would minimize space and the need for food. Such could have been accomplished selecting recently weaned animals that could be self supporting but were still growing and small in size. Such an approach could have reduced the space and feed requirements by up to 2/3rds. Another approach could have been to take pregnant females which would have given them two animals for the space of one.
If the Jaredites were technologically advanced, as some have suggested, they might even have been able to artificially insemminated their animals to get twins and triplets, but that is being too speculative. But the entire adventure of the Jaredites was miraculous, so we should not be surprised if the Lord did provide them with unusual means to accomplish His ends.