Mercury – Inner Helm Extension Harness | 60-Foot Extension | 84-8M0173575

Overview
This 60-foot inner-engine extension harness is built for larger triple- and quad-engine boats where the normal harness simply won’t reach. When the run has to travel through long rigging channels or wrap around multiple bulkheads, this extension keeps you from stretching the wiring or forcing it into awkward bends. It lets the harness follow an easy, natural path so the controls stay steady. On big offshore rigs, that extra length makes rigging and later service a whole lot simpler.

Key Features
    • 60-Foot Extension – Long reach for extended inner-engine routing.
    • Inner-Engine Use – Designed for the inner engines on triple and quad DTS layouts.
    • OEM Connectors – Factory plugs that lock in securely and stay tight.
    • Smoother Routing – Helps avoid sharp corners, pinch points, and rubbing spots.
    • Reliable Signal Path – Keeps throttle and shift communication consistent.

Engine & Boat Compatibility
    • Triple engine
    • Quad engine
    • Inner-engine helm pathways

Performance & Practical Benefits
With this much length to work with, the harness can run cleanly across the boat instead of getting wedged into tight spaces. Controls tend to feel smoother because the wiring isn’t kinked or under tension. It also leaves more room to work when you’re doing maintenance—something that makes a big difference on wide-beam or deep-hull boats. Everything ends up looking cleaner and feeling more predictable.

Why Buy OEM
OEM harnesses handle vibration, heat, and saltwater far better than generic cable. The connectors match Mercury’s system exactly, which helps prevent loose plugs and the weird glitches that come with mismatched wiring. It’s dependable rigging built for real marine use.

FAQ
Q1: How do I know I need the 60-foot version?
A: If the inner-engine run still feels short or forced even with a 50-foot harness, this is the safer and cleaner choice.

Q2: Any setup required?
A: None—just plug it in and route it.

Q3: Good for saltwater boats?
A: Yes. Rinse the area now and then and check the connectors.

Q4: Any install tips?
A: Give it wide, smooth curves and avoid rubbing points to prevent wear.

Q5: What are signs the harness may be wearing out?
A: Hesitant controls, intermittent signals, or visible jacket scuffing along the run.