FWIW, Isp is measured in seconds and by multiplying it times gravity, you get the exhaust velocity. I believe this was done to more easily compare rocket efficiency regardless of units of gravity.

It looks like you're doing this calculation:

Isp * Gravity / Gravity

If you're trying to predict the hover duration, that will depend on the delta V of the vehicle. Then, a hover duration would be:

Delta v / Gravity

Not sure what the expected delta V is for the Dragon though.