Paravane or Toy Boat?

I bought a piece of aluminum and was about to start making a paravane.  But I don't really know how fast the boat will go with the electric motor or how big the paravane should be to give me 50 or 100 lbs pull at that speed.

As I thought about what the paravane should look like so it would stay near the surface and off to one side I realized that it should look very much like my boy Amoni's toy sailboat.  So I explained to him that I could figure out better how big my paravane should be if I did some tests with his sailboat with the sail off and he agreed.  I put on 3 strings tied together and will do a long string from that to  the scale (in Teryn's hand).   The strings should hold the boat at the right angle, like strings to a kite.   If we can walk at 3, 4, or 5 MPH we can see how much the boat will pull on the string.  Then I can have some idea what size the paravane should be.   Plan is to head to the dock after school gets out.  

We put the model in the water and measured 3 to 6 lbs force on the string with probably 3 or 4 MPH.  It works!

You can see more pictures.