[luv-talk] Bouncing engines

An engineering problem to exercise the intellect: I have a water pump powered by an air cooled diesel, all mounted in a frame which in turn sits on two skids parallel to the crankshaft. Air cooled diesels are noisy and leap up and down, a lot, and the pump likes to wander around. I wish to make an earthen pad to sit this on, but I would prefer not to tether it to stakes with bungee cords, as keeping a stake in the ground without the use of a concrete pad is iffy. So, what profile should this pad have, bath tub or mound? I think mound is the likely answer, but before I move the dirt I thought I'd throw it open for debate whilst I try searching on line for it.