Yes, what is so "sooper sekrit" about this hovercraft project that we have to practically torture you to get any information? You mention instructions. There must be a name for this hovercraft written on the instructions, the name of the person who designed it, etc.. Such information might be helpful.

I agree with Steve. It's probably a "380" motor because a 6x3 prop is about right for that motor at 7.2V.