Moshe, the "book of Jasher" has been cited on this forum by others in the past. The Bible does refer a couple of times to a "book of Jasher". Because of this, multiple authors have seen this reference and called their book the "book of Jasher" to make it sound more genuine - there are about 5 completely different "books of Jasher" in existence.
I assume you are referring to the Sefer haYashar midrash when you say the "book of Jasher". This is the least-discredited one, the most widely accepted, but it also may just be a 17th century forgery as no earlier copies exist. It parallels Genesis but with a load of added details, which sound fascinating but include a number of clear disagreements with the Biblical account, making it less likely to be authentic scripture. It may be interesting but I wouldn't be basing any theology on it.
http://en.wikipedia.org/wiki/Sefer_haYa ... midrash%29
However as far as I can see, the Sefer haYashar only states that Noah had one wife (naming her as Naamah, daughter of Enoch). So either I've missed something or you may be referring to a different book by the same name. Please clarify which of the several books of Jasher you are referring to if it isn't this one:
http://www.sacred-texts.com/chr/apo/jasher/
Genesis 7:7 tells us that Noah, his sons, his wife, and his son's wives went with him into the ark. Note that Noah is said to have a "wife", not wives.
1 Peter 3:20 states that 8 people were saved in the ark. This number is confirmed in 2 Peter 2:5. Given there were 4 men, there is no space for any of them to have had more than one wife.
Although it is plausible that Noah married one of his granddaughters following the flood, so could have ended up a polygamist, this is rather wild and pointless speculation. Unless he did that, he had only one wife. Any book that claims otherwise is in disagreement with scripture.