This dolly sits perfectly under the mainhull of your Windrider trimaran. It's size is big enough to support the entire boat, but still small enough to be placed on the trailer with your Windrider on top. Making launching your boat even easier. 
It's very easily disassembled so you can even take it aboard or store it somewhere safe when you are on the water sailing.

 These pictures are of the dolly with optional big balloon wheels for on the beach. Extra price for the bigger wheels and bigger axle is Euro 250,-.