Hello Mark...
The "notches" are there for a couple of reasons. "Traping" is a bad word in my vocabulary. The notches relieve the air from the bottom of the boat, make the stance of the boat wider than what it looks, and also narrows the ride pads. If you wanted to trap more air under the boat, thus making the boat flightier, you can fill in the notches and extend an air trap back further. I am no expert by any means though. These engines put out so much power now, lift is not necessary. For those who don't know, this design holds the IMPBA SAW record. Oh yeah....plans and kits are available. (shameless plug)
Brian
Blazer Marine