Absolutely, the shock wave is more "spread out" in the deep ocean. The disturbance at the surface (the wave) is only, say, a foot high (and many miles wide) in the open ocean.

As the shock wave approaches the shore it "piles up" on itself and forms the tsunami. But with only eight hours warning, you'd have to have a fast boat to get far enough off shore to be safe. You'd probably spend half the time just trying to get out of the harbor.

But a boat would be your best option if you've actually got one.