Attwood SL37-120-1 Gas Spring Lift Support, 120 lb

A gas spring is one of those parts you never think about until it quits. Then every time a hatch drops on your fingers, you remember it exists. The Attwood SL37-120-1 is a marine gas spring, also called a lift support or gas strut, and its whole job is to hold a hinged lid open and lower it down under control. It's rated at 120 pounds of output force, extends to 26.3 inches, and compresses to 16.1 inches when the lid is shut. That works out to 10.2 inches of travel between fully closed and fully open.

Gas springs like this one show up all over a boat. Engine compartment hatches, in-deck fish boxes, livewell lids, rod locker doors, seat bases, and console access panels all lean on a strut to stay up while your hands are busy with something else. Over time the pressurized gas inside starts to weep past the seal. The lid gets heavy, opens slowly, or won't stay up on its own anymore. That's the signal to swap it out, and honestly it's usually a five-minute job with a couple of clips or bolts.

Both ends of this strut use eyelet mounts. That means it pins onto eyelet-style studs or clevis brackets rather than the snap-on ball sockets you'll find on some other configurations, so check which style your boat uses before ordering. The rod measures 8 millimeters and the cylinder body is 18 millimeters, with a 10 millimeter socket sizing. When you're ready to replace an old one, measure it end to end while it's fully extended, note the mounting style, and match those to this unit.

Here's the thing about gas springs. They're sized by three numbers: extended length, compressed length, and force. Get all three right and the new one behaves exactly like the one that came off. Force matters as much as length. Too little and the lid sags shut. Too much and it fights you on every close, or it can even push the lid up on its own. The 120 pound rating here suits a medium to heavy hatch. If your original carried a different number, match what the boat builder spec'd, because that rating was picked for the weight and hinge geometry of that exact lid.

For the longest life, mount it with the rod pointing down when the lid is closed. Rod-down keeps the internal oil sitting against the seal, which is what keeps the strut from drying out and losing pressure early. On wider hatches these run as a matched pair, one on each side. If one side has gone soft, do both at the same time. The other strut is usually not far behind, and matched springs keep the lift even so the lid opens straight instead of racking to one corner.

The SL37-120-1 comes with a black finish that blends into most hatch openings and stands up to the damp, salty air these parts live in day after day. Keep in mind it's a replacement strut, not a full hinge kit, so you'll reuse your existing brackets, studs, and hardware. And if you're hunting for a specific factory part number that's no longer listed, don't get hung up on the label. Match the extended length, the compressed length, and the force rating instead. Those three numbers are what actually decide whether a gas spring holds your hatch the way it should.

Not sure yours is done? Open the lid halfway and let go. A healthy gas spring holds it right there without creeping. If it drifts closed, feels spongy, or slams down, the seal is giving up and it's time for a fresh one. Replacing a worn strut before it fails completely saves you a pinched hand and a lid that won't stay put while you're reaching for gear.