Bed shakers on waterbeds, futons and other surfaces that aren't a standard mattress
Short answer: the instinct is to assume anything unusual — a waterbed, a futon on the floor, a low platform bed — will swallow a bed shaker's vibration the way a thick memory foam mattress does, and for at least one of those the instinct is backwards. A futon or thin mattress laid directly on a hard floor or platform often transmits vibration better than a conventional bed, not worse, because there's less foam in the way and a rigid surface underneath to carry the signal further. A waterbed is the genuinely different case, because the pad is shaking fluid instead of a solid structure. None of this means a shaker won't work on your setup — it means the placement advice written for a standard mattress on a standard frame doesn't automatically transfer, and it's worth five minutes to work out what does.
How a bed shaker actually moves you
A quick recap of the mechanism, since the rest of this page is about how different surfaces change it: a bed shaker's pad contains a small motor with an off-centre weight, which wobbles the pad's casing when it spins. That casing is pressed against whatever you're lying on, and the vibration transfers into that material as mechanical energy before it ever reaches you. Rigid materials pass the vibration along efficiently; soft, absorbent materials convert more of it into heat instead, which is why the same shaker can feel strong on one bed and muted on another with nothing about the device itself changed. How bed shakers actually work covers this in full, and why mattress type changes shaker strength applies it specifically to foam versus innerspring. Everything below is that same physics applied to surfaces those two pages don't cover.
Waterbeds: fluid changes the signal, it doesn't kill it
A waterbed replaces the springs-or-foam structure of a normal mattress with a bladder of water, and water behaves very differently from either. Vibration entering fluid spreads outward as pressure waves rather than staying localised the way it does in a solid structure, which means a shaker pad placed directly against the bladder can end up diffusing its energy across the whole waterbed rather than concentrating it where you're lying. In practice this tends to show up as a broader, sometimes vaguer sensation rather than a sharply localised buzz — some people find this perfectly effective, others find it too diffuse to register clearly.
The more reliable placement on a waterbed is between the bladder and any solid deck or frame component underneath, if your waterbed has one, rather than floating the pad directly on the fluid surface. A rigid contact point gives the vibration a more direct path than fluid alone. If your waterbed is a soft-sided model with a foam surround rather than a hard deck, treat the foam layer the same way you would on a conventional mattress — it will damp the signal the same way any foam does — and consider testing the pad under a pillow instead, which keeps it out of the water question entirely.
Futons, tatami and platform beds: often stronger, not weaker
A futon or thin mattress on a low platform, a tatami mat, or directly on the floor is usually a better transmitter than people expect, for a simple reason: there's less material between the pad and the rigid surface underneath. A thick pillow-top mattress on springs has multiple layers of foam and padding to travel through before hitting anything solid. A futon a few inches thick, resting on a hard platform or floor, has almost none of that — the shaker's vibration reaches the rigid base quickly and that base, being a large connected surface, can carry the vibration across a wider area than a soft, absorbent mattress would.
This is good news if you've been told bed shakers don't suit minimalist or floor-level sleeping setups — the opposite is usually true. Placement is still worth being deliberate about: under the futon, pressed against the platform or floor rather than sandwiched in the futon's own filling, gets you the rigid-surface advantage; buried inside a thick, quilted futon layer gets you something closer to the foam-damping problem a conventional mattress has. If you sleep directly on a tatami mat with a thin cover, treating the mat itself as the "mattress" and placing the pad underneath it, against the floor, tends to work well precisely because tatami and the floor beneath it are both relatively rigid.