You are right Paul. They are pretty flexible. There's nothing on the model to hold them, except a layer of walnut on the outer and inner hull over the 1st planking. There is a top rail which will stiffen them, but I won't put these on until I planked the 2nd layer on the outside. Maybe I'll stop planking the hull for a day or two and trim these down lower where they should be and then add the walnut planking on the inside.
Actually, I wish I hadn't decided to build this kit. I found a set of written directions online for the ship, but they don't really fit this ship. The directions have the same Mantua model # Art 769, but it's single planked and other things are different. The included photos in the build booklet and the printed diagrams that came with the kit are different in some places. I'm just kind of winging it as I go. Was thinking about trashing the hull and use the wood somewhere else. But, decided to finish the build. Think I may make it rough looking - like a pirate ship. Don't know yet.
I think a modeler could put their money to better use on another ship.