Originally Posted by crazyoldboatguy
Early Egyptians sailed the Nile River for millennia. It is suggested that they even transported much material involved in the construction of their monuments and other stone structures. The river was too wide to allow for the use of animals
for towing. Too deep for punting. Quite swift during the annual floods. Lateen rigs were their motive power.
The OP clearly stated that he was writing about a fictional river. He used the Mississippi as a proxy in order to ask his questions. Unless I am mistaken, he is not writing a historically-accurate account. But, the story does require moving a boat upstream on a fictional river not named the Mississippi, and in order to keep the number of characters to a manageable level, he would prefer to use sail power.
In that regard, I think Crazy Old Boat Guy gives a great example of a large river that has been, and still is, sailed regularly. To the OP, some study of the types of boats and sailing rigs that are used on the Nile may give you exactly what you are looking for. The dhows had a simple lateen rig, and the hulls were full keel
. Lots of good internet
info out there to help you flesh out your story.
With the Nile as a model, and going back to your original question, you could allow a believable time for a trip of 250 miles in five or six weeks. That would allow for a couple days spent going aground and having to kedge off, time spent on repairs
do tear and chafe), and time spent waiting on weather
A suggestion I may offer is to have a small rowing dinghy
for three people that is used to scout ahead or ferry
people to shore. It would offer some options for story plot.