I have yet to search the Eggcorn database for this, but I not infrequently on Mudcat see something like the following:

"The ship raised her sails and got under weigh."

Of course "under way" is the expression, and "way" has to do with motion. "Way enough" means at least that amount of motion (and probably not much more) necessary to maintain the power to steer the ship.
The mistaken speaker or writer has probably been led astray by the expression, "to weigh anchor", which I suppose one must do before one can either get way enough or get under way.

Dave Oesterreich