“Many creationists believe that every present day species descended from those few “kinds” that could fit on a boat of known dimensions a few thousand years ago.”
No, that’s not even an accurate statement of the beliefs of young earth, biblical literalist creationists. So, maybe you aught to obtain a rudimentary knowledge of their beliefs before you take it upon yourself to define them for others?
Well then go ahead. Here is your opportunity to discuss a matter you are fully qualified to discuss.
Here I went with what answers in genesis says - a rather mainstream creationist source.
http://www.answersingenesis.org/articles/nab/really-a-flood-and-ark