attwood adjustable boat seat extension post, 13" to 19" height, 2-3/8" diameter, marine-grade aluminum

The Attwood SP-37904 is a 2-3/8" diameter adjustable boat seat extension post that raises seating between 13" and 19" for secure, wobble-free passenger seating on open-water boats.

Replace or upgrade your boat’s passenger seating hardware with a corrosion-resistant, precision-fit extension post engineered for marine conditions. The SP-37904 uses a satin-anodized, marine-grade aluminum shaft, a proprietary wedge bushing and crush-rib bearing system to lock the post rigidly into the base while allowing smooth height adjustment. It’s certified to ABYC Code B for passenger seating hardware and includes a positive locking tab to prevent accidental detachment. This post is not intended for helm or driver seating.

How does this post adjust from 13" to 19"?

The post features a built-in height adjustment mechanism that telescopes within the 2-3/8" diameter tube, letting you set seat height anywhere between 13" and 19". Adjustment is smooth and secure so you can change seating height quickly without compromising stability.

• 13"–19" adjustable range for flexible seating positions
• Telescoping inner tube with positive stop locations
• Easy manual adjustment—no special tools required

What keeps the post stable and wobble-free?

Stability comes from an advanced peripheral bearing system with individually sized crush ribs that create a tight, exact fit inside the base. A secure wedge bushing further locks the post into place and an integrated locking tab prevents unexpected disengagement, so seats remain solid while underway.

• Peripheral bearing with crush ribs eliminates play
• Wedge bushing secures the post into the base
• Locking tab provides positive retention for safety

Is this post durable in saltwater and harsh weather?

The SP-37904 is machined from high-strength marine-grade aluminum with a satin anodized finish designed to resist corrosion from salt, sun and spray. That finish plus robust construction reduces long-term wear and preserves a clean appearance on exposed deck installations.

• Marine-grade aluminum core for structural strength
• Satin anodized surface for enhanced corrosion resistance
• Designed to withstand repeated marine exposure and weathering

Does it meet safety standards and where should it be used?

This extension post is fully certified to ABYC Code B for passenger seating hardware and is intended for passenger seats on open-water boats. It is explicitly not rated for helm or driver seats; use it only on approved passenger seating mounts.

• ABYC Code B certified for passenger boat seating hardware
• Not intended for helm or driver use
• Compatible with bases designed for 2-3/8" diameter posts

Who this is for: Boaters who need a dependable, adjustable seating post for passenger stations—fishing and recreational vessels, charter operators, and anyone replacing worn or corroded passenger seat posts. If you want precise height control, a secure locked fit and long-lasting corrosion resistance in a compact 2-3/8" diameter package (model SP-37904), this post is built for that purpose.