Takayama Model T design investigation

Hey All,

Had a look at the Model T - Takayama , impressive.

So am I right, the rails are 60/40 but really soft and rolled into the bottom ?

How do these reails compare to 50/50 and equally soft ?

How is the bottom configured?

Im planning on making something like this but need to get my head around the bottom contours and where the rolled vee might start ?

Where to put the fin and what type of fin ?

Any help would be great.