Big, Dumb, heavy lift boosters.

>
> With regards to sea launch, what sort of size range of booster, can be
> practically launched rfrom sea? Could we launch a Saturn-V from a sea
> platform?
>

It depends on the size of the platform. Theoretically thewy could be
built any size, it is simply a matter of money.

The thing that made Sea Launch attractive was that there already existed
a proven design for an oil platform which was big enough to launch a
Zenith - the company Kvaerner built it with no difficulty
and for an attractive cost. I doubt if anything much larger than that
is currently available. Also, the bigger they are, the more difficult
(read more expensive) to move around.