There are a lot of hull shapes that use tumblehome. Shouldered tumblehome is actually a flared hull with an abrupt tuck for the last two inches just below the sheer ( the gunwales). These hulls have a lot of secondary stability
Then thee is tumblehome where the hull is flask shaped. The wide part is down low and there is less stability if the hull is heeled.
I don't understand what you mean by use to gunwale. Are you getting pinched? Or are you hitting your hand? What boat are you in?