Mercury 30 HP EFI Outboard, Tiller, Manual Start, 15-inch Shaft (Model 30MHGA)

Power your aluminum fishing boat, jon boat, skiff, or small inflatable with the Mercury 30 HP EFI FourStroke Outboard in its tiller-steer, manual-start, short-shaft configuration. Built around Mercury’s modern 500cc inline three-cylinder FourStroke platform, this engine combines battery-free electronic fuel injection with a lightweight package designed for simple ownership, dependable starting, and efficient performance on small watercraft.

This configuration is made for boaters who value simplicity: no starter motor, no battery requirement, and direct, hands-on tiller control. It is an ideal repower for 14- to 16-foot aluminum boats, car-top and trailer boats, and fishing rigs that run from standard 15-inch transoms.

Battery-free EFI inline three-cylinder power

The heart of this outboard is Mercury’s 500cc inline three-cylinder SOHC FourStroke engine. Unlike a carbureted small outboard, its electronic fuel injection meters fuel precisely across the full operating range, supporting easier starts in cold or hot conditions, smoother idle, and consistent throttle response. Because this EFI system requires no battery, manual-start models gain modern fuel-injection reliability without adding a battery, cables, or a starter motor to the boat.

The engine’s single overhead camshaft drives two valves per cylinder, and CDI ignition with electronic spark advance adjusts timing for strong acceleration across the 5800–6200 RPM full-throttle range. Mercury’s Engine Guardian warning system monitors the engine and alerts the operator to low oil pressure, overheating, over-rev, and sensor issues.

For customers comparing small-outboard options, our guide to Mercury 25 HP versus 30 HP outboards explains the real-world differences in weight, thrust, and boat match.

Key engine features

• 30 HP inline three-cylinder SOHC FourStroke
• 500cc displacement
• Battery-free Electronic Fuel Injection (EFI)
• Full-throttle operating range: 5800–6200 RPM
• CDI ignition with electronic spark advance
• Engine Guardian operator warning system (low oil pressure, overheat, over-rev, sensor failure)
• 2.17:1 gear ratio with forward-neutral-reverse shift
• Through-propeller exhaust
• Water-cooled with thermostat
• Runs on 87-octane unleaded fuel, compatible with up to 10% ethanol
• Three-star CARB ultra-low-emissions rating
• Phantom Black corrosion-resistant finish

Simple tiller control and manual starting

The integrated tiller handle puts throttle, shift, and steering in one hand. The twist-grip throttle includes adjustable friction to hold trolling speed, and the stop button is positioned at the grip for quick shutoff. Forward-neutral-reverse shifting is selected at the tiller, keeping the rigging clean and the cockpit uncluttered.

Manual start on this engine benefits from EFI priming—no choke knob routine—so a firm, even pull is typically all that is needed. Manual-start models keep overall weight down to approximately 145 lbs, making this one of the lighter 30 HP four-strokes available and easier to carry, mount, and stow. Manual-start versions do not include the charging system fitted to electric-start models; an alternator kit is available if you need to power electronics. Browse our outboard rigging and charging accessories.

Need rigging help? Our service team handles full installations, propeller selection, and sea trials—see our outboard services for installation and setup.

15-inch short shaft for standard transoms

This model uses a 15-inch (short) shaft, which suits the standard transom height found on most jon boats, aluminum utility boats, and small skiffs. Correct shaft length keeps the anti-ventilation plate aligned with the hull bottom for proper cooling-water pickup and efficient thrust; running a shaft that is too long or too short can cost speed and, in the worst case, cause overheating.

The gearcase includes shallow-water drive positions, allowing the engine to run tilted up in thin water. If your boat has a 20-inch transom, choose the long-shaft version instead—our guide on how to measure outboard shaft length walks through it step by step, or browse our Mercury 30 HP outboards to compare shaft and start options.

What is included?

The Mercury 30 HP EFI (30MHGA) package includes:

• Mercury 30 HP FourStroke EFI outboard, Phantom Black
• Tiller steering handle (attached)
• Manual (pull) starting system
• 15-inch short-shaft gearcase, 2.17:1 ratio
• Gas-assist tilt with shallow-water drive positions
• Remote 6.6-gallon (25 L) fuel tank with fuel line
• Owner’s documentation and Mercury warranty coverage (3-year limited warranty, extendable with Mercury Product Protection)

The package does not include:

• Propeller (select pitch to suit your boat—see our propeller guide or propeller service)
• Battery, starter motor, or electric-start wiring (not required on this model)
• Remote steering or control box (tiller only)
• Fuel-water separating filter (recommended add-on)

If you are building a complete small-boat rig, explore our Mercury outboard motors range to compare configurations.

Mercury 30 HP EFI versus a conventional carbureted 30 HP

For help choosing the right horsepower class, read 20 HP vs. 30 HP: which small outboard do you need and our outboard buying guide FAQ.

Transom height and fitment

A 15-inch shaft matches a standard 15-inch transom, but transom height alone does not guarantee a perfect setup. Hull deadrise, engine height adjustment, propeller pitch, and load all affect performance.

Before purchasing, check:

• Transom height measured from the hull bottom to the top of the transom
• Boat horsepower rating on the capacity plate
• Transom thickness and mounting-clamp surface condition
• Weight capacity, including fuel, gear, and passengers
• Propeller clearance in turns and at full tilt
• Fuel-line routing to the remote 6.6-gallon tank
• Whether your boat requires a tiller or remote steering setup

Need help confirming compatibility? Contact our marine-engine specialists with your boat’s make, model, transom height, hull material, and typical load, or submit a product inquiry.

Installation, break-in, and safety information

Outboard installation and initial setup should be performed by a qualified marine technician. After installation:

• Verify mounting-clamp fasteners are torqued to specification.
• Check fuel-line connections and primer-bulb orientation.
• Confirm cooling-water flow from the telltale at idle.
• Follow the Mercury break-in procedure for the first hours of operation.
• Test steering swing and throttle/shift operation at the dock.
• Fit the propeller matched to your boat’s weight and use.
• Complete your warranty registration after delivery.

Do not operate the engine if the telltale shows no water flow, fuel is leaking, or any control does not move freely. For scheduled care, see our maintenance schedule by model and winterization service.