Reese
Junior Member
Sorry to jump in....what you guys are talking about is called a "notched transom". As previously mentioned, it does help to get a cleaner stream of water to the prop helping efficiency, but the real purpose is to increase the fulcrum effect at top speed without sacraficing hole shot.
For example a 20 ft. bass boat with a notched transom of 10" along with a setback plate of 10" will have a total setback of 20". Upon take off, the notched section is under water and the boat behaves as if it only had 10" of setback. Once the boat plans the flat keel begins to raise the boat and the CG begins to move towards the transom near the notched section.
At speed, this setup will require less trim from the outboard allowing greater power to be directed towards forward motion. This also explains why 280 hp outboard bass boats routinely hit 100 mph.
For example a 20 ft. bass boat with a notched transom of 10" along with a setback plate of 10" will have a total setback of 20". Upon take off, the notched section is under water and the boat behaves as if it only had 10" of setback. Once the boat plans the flat keel begins to raise the boat and the CG begins to move towards the transom near the notched section.
At speed, this setup will require less trim from the outboard allowing greater power to be directed towards forward motion. This also explains why 280 hp outboard bass boats routinely hit 100 mph.
