Mercury 300CXXL 300HP Outboard – 30in Shaft, Counter Rotation, DTS, V8
For deeper transoms, Mercury 300CXXL produces 300 horsepower. Counter-rotating gears pair with a standard twin, both on 30-inch shafts. Part of the Verado lineup. Owners choose it for steady output without excess weight.
- Rated at 300 horsepower
- 30-inch shaft, standard fit
- Counter-rotating gears for twin engines
- DTS digital throttle and shift
- V8 engine, proven configuration
Description
Deploy the battery-free, 500cc Mercury 25MLH to eliminate heavy starter batteries on remote camp skiffs. The 20-inch shaft block forces aggressive low-end torque, pushing heavily loaded utility boats upstream against morning river currents. Measuring your hull geometry ensures this manual start long shaft mercury outboard fits perfectly.
Clear underwater debris safely in shallow creeks by utilizing the manual tilt bracket as a direct physical fix. You simply grab the rear cowl grip and pull the gearcase upward to prevent impact. Engineers build the 62 kg assembly with low-copper marine aluminum. This physical barrier stops galvanic decay when repowering tall transom utility boats in brackish water.
Key Features of Mercury 25MLH
- Battery-Free EFI: Atomizes fuel perfectly using internal magnetic power, guaranteeing reliable cold-weather pull starts without requiring a 12-volt battery.
- 20-Inch Long Shaft: Places the anti-ventilation plate deeply beneath tall utility transoms, preventing water pump starvation in heavy chop.
- Manual Recoil Starting: Strips heavy starter motors and battery cables completely from your boat, maximizing available gear payload capacity.
- Multi-Function Tiller Handle: Puts throttle, shift, and steering inputs directly into your operating hand for immediate physical obstacle avoidance.
- 17-Amp Charging Alternator: Outputs constant electrical current while running, keeping small deep cycle batteries topped off for fish finders.
- Manual Tilt Bracket: Features a rigid mechanical lock, safely holding the gearcase out of the water physically while docked.
- 500cc Inline-Three Block: Produces massive low-end torque internally, lifting heavy aluminum work boats onto plane much faster.
- Through-Prop Exhaust: Channels toxic combustion gases directly underwater, keeping the aft operator station completely free of smoke.
- Accessible Oil Drain: Simplifies routine crankcase lubrication changes, saving significant time during seasonal maintenance prep without specialized tools.
- 2.17:1 Gear Ratio: Multiplies engine torque effectively, pushing heavily loaded hunting boats upstream against strong river currents.
Why Choose Mercury 25MLH
This specific build fits only 20-inch transoms requiring direct physical tiller control. The extended shaft creates massive drag if mounted on a standard 15-inch boat. You cannot wire this to a forward console steering wheel. Procuring a reliable manual start long shaft outboard secures off-grid independence.
- Confirm a 20-inch vertical measurement from the transom top to the keel.
- Verify the tiller handle sweep path clears your rear bench seating completely.
- Avoid oil slicks on the water utilizing modern four-stroke internal lubrication.
Ideal Application and Vessel Fitment
This 20-inch manual-start tiller engine is engineered specifically for tall-transom aluminum work skiffs, heavy fiberglass camp boats, and commercial river-running hulls. By stripping away heavy electric starter motors and 12-volt battery banks, operators gain maximum payload capacity for remote area fishing gear. The advanced battery-free EFI guarantees this 20 hp long shaft tiller outboard fires instantly in freezing weather, making it the ultimate off-grid power plant for rugged backcountry exploration.
Warranty, Support and Maintenance
Authorized recreational operation receives a 3-Year Limited Warranty alongside a 3-Year Corrosion Warranty. Registered commercial applications fall under a strict 1-Year Limited Warranty with zero corrosion coverage applied to the block. Scheduled maintenance requires replacing gearcase lubricants and changing oil filters at manual-specified intervals. Always save all physical service records. Your engine serial number acts as the only way to source exact genuine replacement parts. Mulmotor provides product-information support before purchase and assistance with order-related questions.
Mercury 300HP 300CXXL Verado Specs
| Brand | Mercury Marine |
| Full Model Code | 300CXXL Verado (Counter Rotation) |
| Engine Type | V8 4.6L 32-Valve DOHC |
| Displacement | 4600 cc |
| Horsepower | 300 HP |
| Full Throttle RPM Range | 5200-6000 RPM |
| Midsection | Advanced MidSection (AMS) |
| Alternator Output | 115 Amps |
| Gear Ratio | 1.85:1 (5.44" Gearcase) |
| Shaft Length | XXL (30 inch) |
| Dry Weight | 272 kg |
| Steering System | Integrated Electro-Hydraulic Power Steering |
| Application | Large Multi-Engine Offshore Vessels, Luxury Cruisers |














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