Freeman Marine Aluminum Deck Rings & Coamings (2400 Series)

Technical Installation Guide: Fitting Freeman Aluminum Coamings

Freeman marine-grade aluminum deck rings are unique in supporting two distinct vessel integration methods: direct welding into structural aluminum decks and mechanical bolt-in fastening on non-metallic structures. Following proper yard procedures ensures continuous watertight integrity and prevents distortion.

1. Welding into Aluminum Decks (5083 / 6082 Marine Alloys)

• Cutout Tolerances: Prepare the deck cutout according to Freeman's official template schedule, allowing a root gap of 1.5–3 mm for full-penetration welding. Align the top coaming flange flush with the finished deck plane.
• Mitigating Thermal Warpage: Aluminum dissipates heat rapidly and distorts easily under uncontrolled thermal input. The ring must be tack-welded in a balanced cross-staggered sequence. Weld out using short, alternating passes while maintaining strict interpass cooling.
• Use of Jigs or Dogged Covers: Keep the hatch cover lightly dogged in place or secure a rigid timber/steel strongback fixture across the ring during welding to maintain coaming planarity and diagonal squareness.

2. Bolt-in Installation on Fiberglass (GRP), Composite & Timber Decks

For composite vessels, sailing yachts, and fiberglass workboats, the aluminum coaming is the exclusive recommended factory frame:

• Fastener Layout & Pitch: Coamings are supplied pre-drilled or drilled on-site by the boatbuilder to match structural frame spacing for 316 / A4 stainless through-bolts.
• Bedding Compound: Thoroughly clean and degrease all mating surfaces. Apply a generous continuous bead of marine polyurethane adhesive/sealant (e.g., Sikaflex 291i) along the cutout flange and around fastener holes to prevent core moisture intrusion.
• Mandatory Isolation with Tef-Gel: Dissimilar metals in marine saltwater environments trigger severe galvanic cell reactions. Always coat stainless steel fastener threads, shanks, and washer contact faces with Tef-Gel anti-corrosion barrier paste. This prevents galvanic oxidation and galling, ensuring fasteners remain serviceable for future refits.

3. Sealing Profiles: Compression vs. Knife-Edge

• Compression Coamings: Feature a raised solid spigot without outer collection gutters. Zero drainage plumbing required. The ideal solution for working decks where fast hose washdown is prioritized.
• Knife-Edge Coamings: Feature a machined knife-edge rim. Requires drainage tubing directed overboard or to deck scuppers. Delivers maximum resistance against heavy green-water seas.