Discover the Sleek Performance of the Lewmar Size 40 Low Profile Hatch

Engineered for modern sailboats and yachts, this Size 40 low profile hatch flange base delivers a seamless blend of style and functionality. Its ultra-slim 1-inch height creates a streamlined deck appearance without sacrificing the essential ventilation and light your vessel needs during long voyages. Crafted with precision, the smoke grey acrylic offers superior UV resistance, ensuring clarity and durability even under intense sun exposure. Weighing just 10.1 pounds, it's a lightweight powerhouse that won't bog down your boat's performance.

Boat owners rave about how this hatch transforms cabin access—quick to open, secure when closed, and built to handle the rigors of offshore conditions. Whether you're upgrading an older setup or outfitting a custom build, its self-supporting design means no extra framing hassles, letting you focus on the water ahead.

Key Features That Set It Apart

• Low Profile Design: Only 1 inch high for a flush, aerodynamic look that reduces wind resistance and enhances aesthetics.
• Smoke Grey Acrylic: 5/16-inch thick window provides natural light filtering and long-lasting protection against yellowing or cracking.
• Self-Supporting System: Stands firm without additional props, ideal for quick access in tight spaces.
• Robust Construction: 9/16-inch lower frame built from marine-grade materials to withstand salt spray, waves, and heavy use.
• Generous Opening: Square 19 5/16 x 19 5/16-inch footprint with rounded corners for safe, comfortable entry.

Detailed Specifications

Precise Dimensions for Perfect Fit

These measurements ensure a hassle-free installation. Note the generous radii for curved deck integrations.

Effortless Installation Guide

Designed for DIY enthusiasts and pros alike, this hatch mounts cleanly to flat surfaces with up to +/- 1mm tolerance. Use M6 (1/4-inch) fasteners at the hinge points for rock-solid security. For the lower frame, opt for 5mm countersunk screws in No.10 UNC or 2 BA sizes. Seal all edges with marine-grade sealant to prevent leaks, and torque evenly to avoid warping. Pro tip: Dry-fit first to confirm alignment, especially on gelcoat decks where minor sanding can perfect the seal.

Why Proper Install Matters

A snug fit not only boosts watertightness but also preserves the hatch's smooth operation over years of use. Skip the guesswork—measure twice, cut once, and enjoy peace of mind on every trip.

Real-World Benefits for Boaters

Beyond specs, this hatch shines in ventilation: the low profile allows 90-degree opening for maximum airflow, keeping cabins fresh without bulky intrusions. Its lightweight build improves stability, crucial for racing or coastal cruising. Smoke grey tint cuts glare for safer navigation below decks, and the thick acrylic shrugs off impacts from errant dock lines or gear. Many skippers pair it with Lewmar's Quick Action arms for even faster handling, but it stands strong solo.

Maintenance Made Simple

• Wipe acrylic with mild soap and microfiber—never abrasives.
• Lubricate hinges annually with PTFE spray for whisper-quiet action.
• Inspect seals seasonally; replace if hardening occurs.
• Avoid prolonged full-open exposure in high winds to prevent stress.

With basic care, expect decades of reliable service, outlasting cheaper alternatives that fog or warp prematurely.