I had not checked out the USOM class page on AMYA in some time. They have posted a bunch of plans that you can download. From my limited knowledge it seems most are from well known people in the class. Great idea, wish more classes would do it.
I looked a while back and there are a few plans on the web. Marine Modeller International published plans now and then. They published a nice set of plans for “Little Wing” with details a few years ago. I think there are some pretty big differences, the IOMs tend to displace a good bit more to fit the rules.