Why dont you stick 1 or 2 longitudinal spars down the length of the mast the help with siffness?

Something like this where he fits the spars..... https://www.youtube.com/watch?v=NxUQJls26OQ

Pics/posts by Mark_australia from seabreeze.com.au Before the epoxy/microballoon paste is applied.... https://www.seabreeze.com.au/Img/Photos/Windsurfing/13310021.jpg Here you can see the microballoon and epoxy paste being applied to the surface. https://www.seabreeze.com.au/Img/Photos/Windsurfing/1...

That's what I mean. ( I build boards). Add glass balloons to epoxy to make a puddy. It's like mayonnaise. Easily sanded and lighter. This. Its microballoons and epoxy that gets pasted over the board to fill any uneveness and pinholes from the epoxy degassing etc. Its easier to sand and gives a real...

Just get an eps blank and go for it, you will not regret the feeling of cruising on a sled you built yourself. The reward and satisfaction is immense and addictive. For inspiration, if you are on Facebook join Backyard Surfboard Shapers.... you will be amazed at what some of the new guys are produci...