For some reason I forgot about modifying my Graupner Wiesel schnellboot almost 15 years ago. I built it according to the plans but then found out the the boat had four shafts and two rudders (see photos). I removed most of the aft bottom with a hole big enough to easily slide one's foot through, sealing it with styrene and a lot of JB Weld.
For the past few years I have been buying the JB Weld in the large tubes five ounces each (pack of two for mixing). Quite a bit cheaper! That is what I plan on using for the current project.