It’s a 3mm Perspex sheet. I was a bit suprised how flexible it is, I was expecting more rigidity. But it’s okay, I will (try to) glue it on the EPS floatability block or add a spar. The final frame is 150×50 cm, the upper triangle base bisector is 50cm (1/3) high. The solar panel is at the stern to put the weight there. The motors are positioned at 50 cm from the stern (1/3 of the hull), which is very forward, but it should be reminded that direction is obtained by applying differential power to the motors, so moving the motors forward makes them closer to the rotation center.