In one word, Don't.
You use a pump when you have been rolled and have been unable to right yourself. Since you mostly roll because the conditions are too difficult for you to handle, if you are able to get back in and upright you need maximum stability immediately. A full cockpit is a liability for that and so must be emptied as quickly as possible.
The electric pump isn't there for laziness reasons, but for speed of emptying. In Australia most people use them in preference to hand or foot pumps for their speed and the ability to get both hands on the paddle at once and one's feet employed for balance.
JohnK

: Has anyone ever tried using a solar powered fountain pump like these: They
: can handle 160litres/hr and have a battery backup.

: I don't want to spend ages trying to hand pump in bad weather, and I'm too
: tight to spend a fortune on a "proper" kayak pump