I contacted the German boater for information abouth the lengt and propeller:
This boat is 42cm long (with Rudder 51cm)
and 6cm/20,5cm wide.
The weight is 450g complete with full Tank and RC Components.
The Engine ist the 0,8ccm Cox and i use a GAUPNER 29 Prop.
For the Hull i use only ply wood, the cavities are filled with
polyurethane foam.
I also post him he link of this topic...
It´s funny to see my Vid on this forum.
and they learned a new german word.
It looks like he is a great guy
Here are the pictures of the boat on the upper video: