Sea-Dog 316 Stainless Steel Fixed Flange Antenna Base

The Sea-Dog 316 Stainless Steel Fixed Flange Antenna Base is a permanent, deck- or surface-mount antenna base for VHF, GPS, TV, Loran, and radar arch antenna installations. Investment cast from 316 stainless steel for maximum corrosion resistance in saltwater environments, it accepts any standard 1"-14 threaded antenna and features a through-base cable routing channel that eliminates the need for a separate cable grommet or deck penetration.

Key Features

• Investment cast 316 stainless steel — superior corrosion resistance for saltwater and offshore use; stronger and more precise than fabricated or cast 304 SS alternatives
• Through-base cable routing — antenna coax feeds directly through the base, eliminating the need for a separate cable grommet and providing a cleaner, more watertight installation
• Integrated silicone sealant recess — the base is designed with a recessed channel that, when filled with silicone sealant, forms a watertight deck seal around the cable exit
• Standard 1"-14 thread — compatible with the industry-standard antenna thread used by virtually all marine VHF, GPS, and AIS antennas
• Fixed flange mount — installs flush to deck, hardtop, or arch surface with three ¼" flathead fasteners (not included) for a low-profile, permanent installation
• Suitable for: VHF, GPS, AIS, TV, Loran antennas, and radar arch applications

Compatible Antennas

• Shakespeare 5309R Galaxy VHF Marine Antenna
• Shakespeare 5226XT Galaxy VHF Marine Band Antenna
• Shakespeare 5218 Black 19" VHF Marine Antenna
• Shakespeare Galaxy 65" Broadband VHF Antenna

Other Sea-Dog Antenna Mounts

• Sea-Dog 316 SS Lever-Action Rail Mount Antenna Bracket — 7/8" to 1" Rail — for rail mounting instead of deck/surface mounting
• Sea-Dog 316 SS Lever-Action Rail Mount Antenna Bracket (Bulk)
• Sea-Dog Nylon Rail Mount Antenna Bracket — 7/8" to 1" Rail — lightweight nylon option for rail mounting
• Sea-Dog Nylon Antenna Stand-Off Bracket — stand-off mount for offset positioning
• Sea-Dog 316 SS Antenna Mount Extension — 12" — raises antenna height above the mounting surface
• Sea-Dog 304 SS Fixed Flange Antenna Base — 1-1/2" — shorter fixed flange base in 304 SS
• Sea-Dog 304 SS Fixed Flange Antenna Base — 4-1/2" — taller fixed flange base in 304 SS
• Sea-Dog Stainless Steel Fixed Antenna Base — 4" H x 2-7/8" Base
• Sea-Dog White Nylon Fixed Antenna Base — 2-13/16" — nylon fixed base for non-corrosive applications
• Sea-Dog 316 SS Adjustable Deck Mount Antenna Base — adjustable angle version for non-horizontal mounting surfaces

Parts Desk Insights

Best use case: This fixed flange base is the right choice when you want a permanent, flush-mounted antenna installation on a flat horizontal surface — hardtop, cabin top, radar arch, or deck. The through-base cable routing is the standout feature: it keeps the coax run clean and eliminates a separate deck penetration, which is particularly valuable on fibreglass decks where additional holes mean additional sealing points. The integrated silicone recess makes achieving a watertight seal straightforward. For installations on a stainless rail rather than a flat surface, the lever-action rail mount bracket is the better fit. For non-horizontal surfaces or angled mounting locations, consider the adjustable deck mount base instead. Note that mounting fasteners (¼" flathead) are not included.