It would appear that the dead rise is around 10ish degrees
With 400 available hp, this boat should fly. our 28 foot aluminum with twin 250’s, pilothouse, 9000 pounds does 54 mph, full cabin, estimated deadrise over 20 degrees.
There are 2 tunnel issues. (These issues may not manifest but we have seen the following occur albeit with slightly different
parameters)
1) At a high speed the wetted area, depending on trim, may be very short. About a 1/4 to 1/3 of the way back from the leading edge of wetted surface there is a high pressure area, the stagnation line. If at high speed the tunnel reaches this area, there is a good chance that the boat may begin to porpoise.
2) Our very first 6 degree outboard jet we installed a tunnel, we did not install lift strakes as we decided that with that shallow of V they may not provide additional lift. We did not realize the importance/significance of of keeping the boat from sliding in a turn. During a tight turn to say starboard the port edge of the tunnel would ventilate from the air from the transom, ie become part of the trailing edge and the pump intake would suck air. I would predict that this interrupted air entrained flow to your prop inlet water could cause issues even though your motor is set back off on a bracket
The consensus appears to be “lose the tunnel”.
With 400 available hp, this boat should fly. our 28 foot aluminum with twin 250’s, pilothouse, 9000 pounds does 54 mph, full cabin, estimated deadrise over 20 degrees.
There are 2 tunnel issues. (These issues may not manifest but we have seen the following occur albeit with slightly different
parameters)
1) At a high speed the wetted area, depending on trim, may be very short. About a 1/4 to 1/3 of the way back from the leading edge of wetted surface there is a high pressure area, the stagnation line. If at high speed the tunnel reaches this area, there is a good chance that the boat may begin to porpoise.
2) Our very first 6 degree outboard jet we installed a tunnel, we did not install lift strakes as we decided that with that shallow of V they may not provide additional lift. We did not realize the importance/significance of of keeping the boat from sliding in a turn. During a tight turn to say starboard the port edge of the tunnel would ventilate from the air from the transom, ie become part of the trailing edge and the pump intake would suck air. I would predict that this interrupted air entrained flow to your prop inlet water could cause issues even though your motor is set back off on a bracket
The consensus appears to be “lose the tunnel”.
