The Dumas I had took a .60, twin rudders. Not a puny .10 - .15 sized airboat for swimming pools. For more information,
http://www3.towerhobbies.com/cgi-bin...P=ML#technotes \
The .19 Swamp Buggy that I started in RC back in 1977 with (2 channel radios were all I could afford as a teenager), also had a flat bottom. Removing the
strakes on the hull really made it slide. It was more fun than the BSB, especially with a .32-.40 on it. Kept it until 2005 when I ditched my fins for wings.
Edit:
Pictures added of the .60 that was converted over to a better hull. I also covered the "bird bath" on the top deck as it serves no purpose but to catch more water, if you use a .60 that is. Height changes aren't needed with a 10X8 prop. As I recall raising the height of the rudders did a better job. I used a Webra Speed .60, today you'll just have to settle for O.S.