Launching Ramp

Hellol

It would be a gradual accelleration. The size of the max payload would be
governed by the mass of the water. Other considerations are whether the
payload had a booster attached.

Manned payloads sounds a bit ambitious for a first try. I am not advocating
that right now. Ask me after some unmanned payloads are launched
successfully. ;)

Where the electricity comes from is irrelevant for a pumping operation.
Windmills might be adequate.

The Savage design was in an evacuated tube, as i understand. I don't think
they ever worked out how to get the payload out of it and into the thinner,
but still present, air over MT. Kilamonjaro. OTEC is a great idea but is it
necessary to transmit power over 3000 miles.

I think the Andes would be a great location. High and on the equator with
lots of water nearby.

I concede this would be a massive civil engineering project but it is all
low-tech so it becomes just a matter of time and money.