Shock-Absorbing Boat Seats and Pedestals: Choosing, Installing and Adjusting

Remove the old seat and pedestal and look at the floor. It must be solid. Probe around the old holes for soft, wet or rotten core and check the old fasteners. A shock-absorbing seat passes big loads into the floor, so a weak spot will crack or pull out. Our seat pedestal mounts guide covers repairing a soft floor and making backing plates.

Boating Magazine's installers checked under the deck first so no wires, hoses or other parts would be damaged by the drill. Use a flashlight and mirror through hatches or access plates. Mark anything that runs under the new footprint. Plan how you'll reach the nuts from below; if you can't, see our through-bolting guide for options. BoatUS suggests that if there's no access at all, a deck inspection port nearby (not right next to the seat footprint, which would weaken the deck there) lets you look underneath and reach the nuts. Bolting into a structural beam or stringer under the deck, where there is one, beats relying on thin deck alone.

Most pedestals and bases come with a template. Center it over the old footprint (reusing old holes only if they line up and are sound), orient it the way the maker shows (usually square to the boat's centerline), and mark the holes. Fill and seal any old holes you won't reuse so water can't get into the core. Don Casey, writing for BoatUS about replacement seating on plywood or wood-cored decks, prefers epoxy filler for the old holes (sealant also works) and explains why a screw alone doesn't seal a hole: the loads on a seat slowly crush the wood fibers around the threads, opening a gap that lets water in and starts rot, and he notes it tends to happen quickly. That's one more reason to through-bolt a suspension seat and seal every fastener.

Before marking, sit in the seat position and stand in front of it: BoatUS reminds installers that the driver should reach the wheel and throttle comfortably both ways on a center console. A marine tech's trick from the same article keeps the base from shifting while you drill: drill one hole and fit a fastener, then drill and fasten the hole directly opposite, drill the rest, and only then lift the base off to clean up and seal. The result is straight fasteners that load the deck evenly, which helps the sealant last.

Drill with a sharp bit; a right-angle drill guide keeps holes square to the deck, as in Boating Magazine's install. On a cored deck, seal the exposed core in each hole (our deck hardware rebedding guide explains how) so water can't soak in later.

Bed the holes and the base flange with marine sealant. Through-bolt with stainless bolts long enough to pass through the base, deck and backing plate (or large washers), with nylon-insert lock nuts fully engaged. Use threadlocker if the maker calls for it, and tighten to the maker's spec. Wood screws into a deck are not enough for a suspension seat.

Air-spring pedestals and suspension bases are adjusted through a valve like the one on a car tire (a Schrader valve). Boating Magazine positioned its pedestal so the side fill port was easy to reach, and notes that remote fill kits exist when the valve ends up hidden. Think about this before you tighten everything down.

Bolt the seat to the top plate or adapter with the hardware and threadlocker the maker specifies. Check that swivels, slides and height locks work. On height-adjustable pedestals, Boating Magazine notes you may need to lift the seat while the pin is released, then bounce in the seat to make sure the pin has locked.

A suspension seat moves. Shockwave, for example, says its base moves the seat about 1.5 inches forward when fully compressed. Push the seat down through its full travel (or sit and bounce) and check it can't hit the console, steering wheel, throttle, a cooler or a passenger's knees, and that the driver can still reach every control.

This is the step most owners skip, and it decides how well the seat works.

• With the usual driver sitting normally, check the maker's indicator. Boating Magazine's pedestal uses an O-ring on the shaft that should sit at or below a marked line with the rider seated; if not, you add air in small steps until it does.
• Shockwave says the shock should be pressurized to match the occupant's weight, aims for a set amount of "sag" (its FAQ gives about 20 to 25 percent when set correctly), and suggests starting on the soft setting.
• Use a pump with a gauge, add or release air in small steps, and check again after each change.
• Remove the pump before riding. Shockwave's how-to videos specifically warn about this.

Too soft and the seat bottoms out with a bang; too hard and it barely moves. Follow your own seat's instructions for the exact procedure and pressures.

Shockwave recommends keeping a pump aboard and readjusting when someone much heavier or lighter than the usual rider (more than about 50 pounds difference) uses the seat. Mark the usual settings on a small tag or in BoatMend so it's quick to switch back.

Take a short run in moderate conditions first. Listen for knocks or creaks from the base, watch for the seat bottoming out, and feel whether it's too bouncy. Adjust and repeat. Check the mounting bolts again after the first few outings.

Shockwave's cleaning routine for its bases, which suits most suspension seats:

• Wipe or rinse the base with fresh water after use.
• Wipe metal and painted parts, bolt heads and nuts with a corrosion inhibitor on a cloth.
• Give the shock shaft only a thin film and wipe off the excess so grit doesn't stick to it.
• Repeat after every trip, or about every 30 days.

Shockwave recommends checking shock pressure at least once a year. If a seat keeps losing pressure, spray soapy water on the valve and air fittings and look for bubbles; the valve stem is a common leak point and can usually be replaced with the maker's part and tool. A shock that leaks oil, sticks or clunks needs the maker's service or replacement.