Every question, answered.

That's the surface it's built to answer first. The wide flexible base spreads across the cushion instead of sinking a point into the foam, and the fins keep the drink from rattling loose as the boat moves. Bump it and it settles back instead of tipping.

Movement is the whole design brief — a boat is never actually still. The base flexes with whatever it's sitting on and brings the drink back level when a wake rolls through or the hull comes up on plane. It resists tipping; a direct hard hit still gets through, but a rolling wake is exactly what it's built to shrug off.

Measure the bottom, not the rim. A base of 2 to 3 inches across fits — the 40 oz Stanley does. Handled travel mugs don't; the handle sits where a fin needs to grip.

No. Nothing drills, clamps, or suctions to anything on the boat. It sits on top of whatever's flat-ish nearby — the cushion, the cooler lid, the dash — and moves seat to seat in a second.

No — it sinks, the same as almost anything else that goes overboard, and it's worth saying plainly. Soaking it in spray, rain, or a hosed-down deck doesn't bother the material at all. What it can't do is come back up on its own if it goes over the gunwale into open water, so keep it inboard the same as you would a phone.

Rinse it with the hose along with everything else that came off the boat, or run it through the dishwasher. It's one piece of flexible material with nothing to come apart and nothing for salt to work into.

It's not the rigid plastic that goes brittle after a summer in the sun — one piece of flexible material, no metal fittings exposed to spray, nothing to rust. It stows however you already stow your gear.

Yes — that's a moving, crowded, uneven situation, and this handles all three. It grips the vinyl, the gunwale, or the cooler lid the same as it does underway, so a bump from the boat tied up next to you doesn't end the drink.

It's called the Steadi, molded in small runs in Orange, California by Steadi Labs. Every order ships free from steadilabs.com, with 30 days to change your mind.

Most boats do fine with one or two for the seats people actually use — the bow lounge and the cooler lid see the most action, since the factory holders already cover the helm. Add a third for the sandbar raft-up if the boat regularly hosts a full crew; since nothing clamps or mounts, it moves seat to seat in a second instead of needing one per fixed spot.

It's a practical one — most boat owners already know their factory holders are too few and too small for a 30 to 40 oz tumbler, and this solves that the moment it's out of the box, no drilling or installing required. It also travels: the same base works the boat, the dock, and the tailgate at the ramp.

A gimbaled holder is a real fix for one specific problem — a sailboat heeling under sail — and it does that by staying bolted to a rail or bulkhead, one holder per seat, wherever it's installed. This doesn't mount to anything, so it isn't limited to the one seat it's fastened to; it settles a drink back level through a wake or a turn the same way, but it goes wherever you set it down.

Alongside. The helm holders are fine for what fits in them — leave those as they are. This covers everywhere the boat didn't build a holder at all: the vinyl cushions, the cooler lid, the gunwale, the dash, anywhere someone's actually sitting.

Both ends of that range fit. A standard 12 oz can runs about a 2.6-inch base and a slim seltzer can — White Claw, Truly — narrows to about 2.3 inches, both comfortably inside the fins. The same base also takes the 40 oz Stanley tumbler at the wide end, so it's not sized around one drink.

A smooth-bottomed travel mug or thermos without a handle fits and stays put the same as any other container in the 2 to 3 inch range — no more walking across the dash with the engine vibration. A handled version is the one honest exception: the base is the right size, but the handle sits exactly where a fin needs to close around it.

Neither bothers it. It's one piece of flexible material with no metal fittings for salt to work into and nothing that corrodes, so it works the same tied up on a saltwater flat as it does on a freshwater lake. Rinse it with the hose along with the rest of the boat at the end of the day.

Yes — there's nothing mounted to remove and nothing that rusts or seizes sitting in a hatch or a rod locker between outings. It's ready to set back down the next time the boat comes off the trailer.

Any handleless kid's bottle or cup with a base in the 2 to 3 inch range fits the same as an adult's — run the sticky-note check against the specific bottle if you're unsure, since kids' bottles run narrower than a standard can on the small end.