In this type of hull 25 to 30 mph it would be wanting to be on top of the water planning as speed increases then the tunnel is compressing the air and the faster its goes the higher its will climb out and on top and at 70mph its would be literally flying !! the optimum angle of attach would be built as to the same as the planes some where in 3 to 5 degrees so everything all works together at the same time ! With this type of hull form all of the hulls bottom surfaces contribute to lifting water doesn't climb any where even inside the tunnel !! the pressure of the air is slowing gaining pressure and being compressed till it finally reaches the transom ! Yes all this has been describes more than once and still no one has spent enough time looking ! Its not a catamaran !! because cats by nature have narrow hulls they provide little in the way of lift ! because the tunnel between there hulls is much bigger and higher it also contributes almost nothing to lifting the cat so they plough through the water and ride much deeper . Think how many racing cats are seen out on the water?? non at all ,because they are not the same as a tunnel , they are slower and DO NOT PERFORM WELL!!!