Attwood Marine ST31 Gas Spring, Stainless Steel, 7.5 in Extended, 5.25 in Compressed

Overview

The Attwood Marine Stainless Standard Series Gas Spring is a stainless gas spring for supporting boat hatches, lids, access panels, and storage compartments where controlled lift and hold-open support are needed. This series uses an 8 mm rod and 18 mm cylinder, with a 7.50 in extended length, 5.25 in compressed length, and 2.25 in stroke.

Its stainless steel shell and rod help it stand up to damp, salty, and exposed marine locations better than painted or plain steel supports. The 10 mm socket style is suited for common gas spring mounting hardware, making it useful for hatch support replacements or new installations where the mounting geometry matches the listed compressed and extended lengths.

Key features

• Stainless steel shell and rod for better corrosion resistance around bilges, lockers, cockpit hatches, and other wet areas on board.
• 7.50 in extended length and 5.25 in compressed length, with a 2.25 in stroke for compact hatch and lid applications.
• 8 mm rod and 18 mm cylinder size for standard-duty marine hatch support use.
• 10 mm socket ends for use with compatible ball studs and mounting brackets.
• Available in several output-force ratings so the same body size can be matched to different hatch weights and opening angles.
• Helps lift, support, and control movement on access panels where a loose lid could be inconvenient or unsafe during maintenance or storage access.

Variants

This product is offered in multiple output-force configurations within the same Stainless Standard Series format. The variant range covers lighter and heavier hatch-support needs while keeping the same listed 7.50 in extended length, 5.25 in compressed length, 2.25 in stroke, 8 mm rod, 18 mm cylinder, and 10 mm socket style.

The force rating is the main difference across the variants, with options ranging from 20 lb up to 80 lb. In practical terms, the correct force depends on the hatch weight, hatch size, hinge position, mounting points, and desired opening feel, so matching the existing gas spring rating is often the safest path when replacing an original support.

Installation and fit

Fit should be checked against the existing gas spring or the planned mounting layout before installation. The extended length, compressed length, stroke, socket size, and output force all matter, especially on boat hatches where a small change in geometry can affect how far the lid opens and how firmly it stays raised.

For replacements, compare the printed force rating on the old spring when it is still readable. When adding a support to a new hatch, the hatch weight and bracket location should be considered together, since the same force rating can feel different depending on leverage and opening angle.

Use cases on board

This gas spring is a good match for boat owners replacing worn hatch supports or building out access lids in areas such as cockpit storage, deck compartments, console access panels, engine-room covers, and cabin lockers. The stainless construction makes sense where the support may see spray, moisture, washdowns, or regular temperature changes.

It is a practical choice for small powerboats, fishing boats, cruisers, and other vessels where a hatch needs to open smoothly and stay supported while gear is loaded, systems are checked, or routine maintenance is handled.

Maintenance and care

Rinse the spring and socket area with fresh water when it is exposed to salt spray or washdown chemicals. Keep the rod clean and avoid scoring or clamping it, since damage to the rod surface can shorten seal life and reduce holding performance over time.

Mounting hardware should be checked periodically for looseness, especially on lids that are opened often or exposed to vibration underway. Replace the gas spring when it no longer supports the hatch safely or when movement becomes uneven.