Freeman Marine Steel Deck Rings & Coamings (2400 Series)

Technical Guide: Welding Freeman Steel Coamings into Steel Decks

Freeman structural steel deck rings are engineered exclusively for weld-in installation into steel hulls. They cannot be bolted. To ensure the coaming maintains perfect planar alignment during and after welding, standard shipyard welding procedures must be strictly observed.

1. Fit-up and Deck Cutout Tolerances

• Close Cutout Tolerances: Cut the opening in the deck plating as close to the coaming dimensions as practical. Excessive gaps requiring heavy weld buildup introduce unnecessary heat into the structure, which is the primary cause of coaming warpage.
• Planar Alignment: Align the coaming so that the top edge rests flush with the finished steel deck surface. Account for any deck camber or sheer to ensure the sealing plane remains unstressed.

2. Recommended Welding Sequence

• Tack Welding Sequence: Working from below deck, place a 25 mm (1-inch) tack weld at one point on the perimeter. Place the second tack weld as far as possible on the opposite side (180 degrees). Continue tacking in a cross-staggered sequence until welds are approximately 150 mm (6 inches) apart along the entire coaming perimeter. This alternating sequence prevents localized heat buildup.
• Final Full Penetration Welds: Once tacking is completed and verified, fully weld the perimeter from the topside using short, balanced passes with adequate interpass cooling.
• Strongback Fixturing: Keep the hatch cover lightly dogged in place or clamp a rigid steel strongback across the coaming during welding to ensure the sealing surface remains completely flat.

3. Sealing Profiles: Compression vs. Knife-Edge

• Compression Coamings: Feature a raised solid spigot without an outer collection gutter. Requires zero drain plumbing and is the proven choice for working decks where fish debris, grit, and ice must be washed off effortlessly.
• Knife-Edge Coamings: Feature a machined knife-edge rim flanked by an integrated perimeter drainage gutter. The gutter captures deck runoff, allowing the boatyard to install a drain fitting in the gutter base if desired to discharge standing water before the hatch is opened.

4. Hinged vs. Lift-Out Steel Coamings

If your hatch is hinged (suffix -H or -HK), the steel ring incorporates integrated mounting lugs to secure Freeman's heavy-duty marine hinge pins. The hinge mechanism allows the cover to open past 180 degrees, resting flat against the deck plating to prevent heavy seas or wind gusts from slamming the hatch shut.