I have two Boat trailer frames which are brand new and galvanised. They were made for the Mitcham Spitfires and Almarine boats, but easily adapted for similar boats.
The first picture is a finished one with a Mitcham OB on it. They tow like a dream and easy to handle, plus the tow bar is removable.
The attached second picture shows the frame and they are sold as the second picture displays, no wheels etc. I am asking £160 for each trailer frame. Email me using the letter under my name on the left.