Well I surmise it's a typical case of the faster you get the boat to go, everything changes. When the hull first came out all of the gas scale boats were slower and they worked fine. As more horsepower and better props are developed and speeds picked up the hull was packing more air in the tunnel and the frontal area of the sponsons had more aero drag that was pushing the nose up and so the same hull became a little flighty, and consequently required strut adjustments and more nose weight to stay stable and on the water. Better to have weight that's actually doing something than just adding dead weight like lead. Notice how shallow the modern unlimted's sponsons are compared to boats like the Dayton Walther you want to build. The faster you go then the more the aerodynamics have to altered for the stability of the boat ride. Remember, the center section is a wing.
An example is the scale roundnose nitro boats I built had radio boxes that came up from the bottom in front of the motor rather than adding lead for nose weight.
