Some models, such as the 38 Open, came from the factory with a rub rail on the swim platform. Take a look at some pictures online to see where you'd end up.
I just replaced the platform rub rail on my Sovran. Tiara sourced the 2” ss rail from an outfit called Marine Industries in northern Michigan. Tiara customer service provided the dimensional drawings and Marine Industries still retained the tooling to radius the corners. Not sure if they also provided the platform rail for the open but I’m sure a note to Tiara customer service will help you out.
Marine industries website is: [Only registered and activated users can see links Click here to register]