New washboards can be made from plywood or from plastic. For ease of handling and storeage it is usual for the washboards to be in two parts although a one part washboard is sometimes used for winter.
Wooden washboards are best made from teak faced marine ply with a solid piece of timber along the bottom edge and ideally a drip rail on the outside lower edge of the upper board. Suitable marine ply can be purchased from Robbins Timber in Bristol and is available in quarter and half full sheets. Finish the washboards in polyurethane varnish to withstand knocks and protect the wood. Alternatively formica sheet can be bonded to the outside surface to give a very hard wearing surface although it does add weight to the washboard. A ventillator can be fitted in the upper washboard.
Teak faced marine ply with drip rail and solid lower edge
These are very strong and should be made from acrylic which can be a dark neutral tint or a translucent white. The tint prevents people from looking into the yacht. Polycarbonate is not recommended as it is less resistant to UV and scratches more easily.
If you want perspex washboards to remain pristine then you need somewhere safe to keep them when you are on the boat. Perhaps a canvas bag for each half? The wooden washboards take a lot of knocks when stowed below with other stuff but don't show the abuse like Perspex.
Teak faced marine ply from Robbins Timber
Plastic from here The Plastic Man