Attwood SL36-40-1 Gas Spring Lift Support, 40 lb

When a hatch won't stay up on its own, or slams down on your fingers, the gas spring behind it is usually the culprit. The Attwood SL36-40-1 is a gas-charged lift support built to hold and cushion the lids, hatches, and covers you open a hundred times a season. It puts out 40 pounds of force, extends to 17.2 inches, and compresses down to 10.2 inches, so it does its work over 7 inches of travel.

A gas spring is a sealed cylinder with pressurized gas and a little oil inside. Push the rod in and the gas compresses, push back and it wants to extend again. That's what holds your hatch open and keeps it from dropping. This one runs an 8 millimeter rod inside an 18 millimeter cylinder body, which is a common mid-size strut on plenty of boats. The 40 pound output force is the number that matters most when you're matching a replacement. Too little and the lid drifts shut. Too much and it fights you when you try to close it.

Both ends use eyelet mounts, so you're bolting through a loop rather than snapping onto a ball stud. That makes it a straightforward swap on any bracket already set up for eyelet ends, and it gives you a solid, rattle-free connection. The socket measures 10 millimeters, so size your hardware to match. If your old strut used eyelet ends too, this drops right in.

Where does a strut like this earn its keep? Think engine hatches on a center console, the lid on an in-deck fish box or ski locker, a livewell cover, a rear-facing seat base, or a console access door. Anywhere a lid needs to stay put in the up position and close gently instead of guillotining down. Boaters also grab these for anchor lockers and battery compartment lids. If you've got a hatch that used to hold itself open and now flops around, a tired gas spring is almost always why.

Sizing a replacement is mostly about three numbers. Extended length sets how far the lid opens, compressed length has to fit the space when the lid is shut, and output force decides whether it actually holds the weight. This SL36-40-1 gives you 17.2 inches open, 10.2 inches closed, and 40 pounds of push. Measure your old strut end to end in both positions before you order, and check the force rating stamped on the cylinder if you can still read it. Match those and you're set.

Installation is about as simple as boat projects get. Most struts mount with the cylinder body up and the rod pointing down, which keeps the internal oil where it belongs and helps the seal last. Support the hatch while you swap the strut so nothing drops on you. Snug the eyelet bolts, cycle the lid a few times, and you're done. No charging, no adjustment, nothing to maintain. When it eventually wears out, you just replace it.

Attwood has been building marine hardware for over a century, and their gas springs are a common sight in boat lockers and transoms across the country. This one ships in bulk packaging, which keeps the cost down when you're buying a functional replacement part rather than a boxed retail item. It's the kind of unglamorous piece of gear that you never think about until it quits, and then it's the only thing you care about. Keep a spare aboard if you've got a hatch you rely on.

A quick word on what this isn't. It's a lift support, not a locking gas strut, so it won't lock rigid in place at a set point. It holds by gas pressure, which is exactly what you want for a hatch or lid. If your existing mounts use ball studs instead of eyelets, you'll want a strut with matching ends or a set of eyelet brackets to convert them.