I dont know is tunnel concave right word what i mean, concave edges goes parallel to tip to tip.
I have made my boards "normal" concave, edges follows outline shape flat section 2-5 cm. These board are smooth to ride at chops, and i think they plane better than flat bottom.
Now i am thinking to remod my two years old 170 x 42 lightwind weapon. Shorten it to 135 cm and put fliptip to ends if needed.
But what if i change 5 mm concave to 5 mm tunnel concave and put only one fin per end midle concave, to reduce drag? Les fin and straight tunnel.
Has someone test both type concaves, if yes please let us know what you think.
Thank 4 advance, Tom