Originally Posted by manyboats
Sounds like some of the gears that were available for the war stuff to multiply the power of DD that powered almost everything at the time.
A back yard twin shaft single engine arrangement could be cobbled together w toothed belts like the HTD. One would probably need to do w/o counter rotating props though.
Don't believe there's an issue with counter rotating as the input shafts on most transmissions are in one direction...rotation direction of the prop is handled by the gearbox....at least that how the Twin Disk in our boat work.