If you have the old washboard for a pattern then take it to a company that sell plastic sheeting material. Ask if they can cut it to your shape as some just supply sheet material. I found a company in Portsmouth but that may be a bit far for you to go. It was a lot cheaper than any boatbuilder quoted me. The material they used was far stronger than the original. If you have the same lock as I had (I assume they are fairly standard) then it is very easy to fit it to the new washboard.