boat physics question

When you suddenly take off in a speed boat (ski boat...whatever you want to call it) the front-end raises up from the torque. When you gain enough speed, the boat levels out. We used to call that "planing" when we'd be out on a boat fishing or water skiing. Heck, my father's old 17' v-bottom boat with a Johnson 80hp outboard could plane.

What's going on from a physics standpoint? I'm trying to emulate it with Newton but I'm having a rough time.

Here's an interesting bit of info on planing:

http://www.bluejacketboats.com/planing_boat_theory.htm

It's the way the boat is built and the friction with the water that will make it behave as it does. I've implemented water physics for a sphere with Newton, works pretty well. Yet, in newton, you have to define the center of the 3D model so it knows where it's the heaviest. It's probably akward the way newton works... Maybe there are more tricks to making a proper floating object.

This is about all I can do with my shabby self. Have fun lol.

Arrows to control and mouse to look around.

Graphics3D 1024,768,32,2
SetBuffer BackBuffer()

SeedRnd MilliSecs()

light=CreateLight()

AmbientLight 100,100,100

Global boatpiv=CreatePivot()
PositionEntity boatpiv,0,700,0

Global boat = CreateCube(boatpiv)
ScaleMesh boat,8,4,16
PositionEntity boat,0,10,0

Global thrust#
Global roll#
Global planed

Global camera=CreateCamera(boat)

CameraRange Camera,1,100000
CameraZoom camera,1.6
PositionEntity camera,5,10,-5

Type buoy
	Field mesh
End Type

buoy = CreateCube()
ScaleEntity buoy,4,16,4
HideEntity buoy

For i = 1 To 30
	b.buoy = New buoy
	b\mesh = CopyEntity (buoy)
	EntityColor b\mesh,Rnd(0,255),Rnd(0,255),Rnd(0,255)
	PositionEntity b\mesh,Rnd(-6000,6000),700,Rnd(-6000,6000)
	EntityAutoFade b\mesh,6000,7000
Next

Type thing
	Field mesh
End Type

thing = CreateCube()
ScaleEntity thing,120,120,120

For i = 1 To 10
	t.thing = New thing
	t\mesh = CopyEntity (thing)
	RotateEntity thing,0,Rnd(1,100),45
	EntityColor t\mesh,0,100,0
	PositionEntity t\mesh,Rnd(-6000,6000),700,Rnd(-6000,6000)
	EntityAutoFade t\mesh,6000,7000
Next

tex = CreateTexture ( 256, 256, 11 )

SetBuffer TextureBuffer ( tex )
For i = 0 To 4
	Rect i, i, 256 - i - i, 256 - i - i, False
Next
For y = 5 To 250
	For x = 5 To 250
		WritePixel x, y, 0
	Next
Next

SetBuffer BackBuffer ()

CameraClsColor camera,100,100,255

ground = CreatePlane()
PositionEntity ground,0,650,0
ScaleTexture tex,5,5
EntityTexture ground,tex
EntityFX ground,9

water = CreatePlane()
EntityColor water,56,200,56
EntityAlpha water,.8
PositionEntity water,0,700,0

MoveMouse GraphicsWidth()/2,GraphicsHeight()/2

Const FPS=60
period=1000/FPS 
time=MilliSecs()-period

While Not KeyHit(1)
Repeat
	elapsed=MilliSecs()-time
Until elapsed
	ticks=elapsed/period
	tween#=Float(elapsed Mod period)/Float(period)

	For k=1 To ticks
            time=time+period

KeyControl()

Next

RenderWorld()

mouselook(camera)

Text 10,40,EntityX(boatpiv)
Text 10,60,EntityY(boatpiv)
Text 10,80,EntityZ(boatpiv)

Text 5,130,"acc: "+thrust
Text 5,150,"planed: "+planed

Flip 0

Wend

End

Function mouselook(ent)

	mxspd#=MouseXSpeed()*0.25
	myspd#=MouseYSpeed()*0.25

	MoveMouse GraphicsWidth()/2,GraphicsHeight()/2	
	
	campitch#=EntityPitch(ent)+myspd#
	
	If campitch#<-85 Then campitch#=-85
	If campitch#>85 Then campitch#=85
	
	RotateEntity ent,campitch#,EntityYaw(ent)-mxspd#,-roll*4
	
End Function

Function KeyControl()
	
	If KeyDown(200)
		thrust = thrust + .06
	EndIf
	
	If KeyDown(208)
		thrust = thrust - .04
	EndIf
	
	If thrust > 8 Then thrust = 8
	
	If thrust < 0 Then thrust = 0
	
	MoveEntity boatpiv,0,0,thrust
	
	If KeyDown(203)
		If roll < 5 Then roll# = roll + thrust * .004
	Else If KeyDown(205)
		If roll > -5 Then roll# = roll - thrust * .004
	Else
		roll = roll * .94
	EndIf
	
	If planed = True
		RotateEntity boat,EntityPitch(boat)*.994,0,0
	Else
		RotateEntity boat,-thrust*1.6,0,0
	EndIf

	If thrust > 7.0
		planed = True
	Else If thrust < .5
		planed = False
	EndIf

	RotateEntity boatpiv,0,EntityYaw(boatpiv)+(roll*.4),roll*6

	TurnEntity boatpiv,Sin(MilliSecs()/5)/5,0,Cos(MilliSecs()/5)/5
	
	For b.buoy = Each buoy
		TurnEntity b\mesh,Sin(MilliSecs()/5)/8,0,Cos(MilliSecs()/5)/8
	Next
	
	If KeyHit(16)
		PositionEntity camera,5,10,-5
	Else If KeyHit(18)
		PositionEntity camera,5,16,-5
	EndIf
	
End Function