6 Best Short Shaft Outboard Motors For Small Fishing Boats
Find the ideal short shaft outboard for your fishing boat. We compare top models based on reliability, fuel efficiency, and weight for your next trip.
Selecting the right outboard motor can transform a modest utility boat into a highly capable fishing machine. Whether navigating shallow marshes, exploring remote lakes, or setting up a compact dinghy for a liveaboard sailboat, weight and shaft length dictate success. Finding the perfect short shaft motor requires balancing portable design with raw, reliable performance.
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Suzuki DF2.5S: Best Lightweight Pick
The Suzuki DF2.5S stands out as the ultimate lightweight champion in the portable marine market. Tipping the scales at a mere 29 pounds, this four-stroke motor is light enough to carry in one hand down a steep, slippery riverbank. For solo anglers using small inflatables or square-stern canoes, it eliminates the back-breaking strain of traditional motor transportation.
Despite its featherweight design, the engine offers robust features like water cooling and a full 360-degree steering capability. Because it lacks a dedicated reverse gear, drivers must rotate the entire motor 180 degrees to back up, a minor tradeoff that keeps the overall build incredibly simple. The integral one-liter fuel tank keeps the deck free of clutter and external hoses.
This motor is the ideal choice for solo adventurers and kayak anglers who prioritize portability above all else. If carrying capacity is limited or every pound counts on a fragile transom, this ultra-light option is the absolute winner.
Yamaha F6SMHA: Most Reliable Workhorse
The Yamaha F6SMHA represents the gold standard of durability and smooth operation in the portable class. Weighing in at 59 pounds, this single-cylinder, 139cc engine delivers a substantial power upgrade over ultra-light models without becoming too heavy for one person to mount. Its reputation for bulletproof reliability makes it a favorite among off-grid cabins and remote wilderness guides.
Operating this motor is an exceptionally smooth experience thanks to Yamaha’s advanced dampening system, which absorbs vibrations before they reach the tiller. The motor also features a convenient three-way fuel storage system, allowing easy switching between the built-in tank and an external tank for longer journeys. It also includes an oil leak prevention system, meaning it can be stored on either side without oil escaping.
This is the motor for anglers who demand absolute reliability in remote waters where towing help does not exist. If peace of mind and legendary starting reliability are the primary goals, this workhorse is the perfect investment.
Mercury 9.9MH: Best for Speed and Power
The Mercury 9.9MH delivers the muscular acceleration and torque required to get heavy utility hulls up on a plane. Weighing 84 pounds, this twin-cylinder, 208cc machine is at the upper limit of portability but compensates with incredible power-to-weight performance. It turns a standard 12-to-14-foot aluminum Jon boat into a fast, highly responsive fishing craft.
The standout feature of this motor is Mercury’s exclusive multi-function tiller handle. This design integrates shifting, throttle control, stopping, and steering into a single, intuitive handgrip, allowing operators to keep one hand free for casting or navigating. The manual tilt system offers multiple positions, making it easy to run through shallow flats without damaging the propeller.
Choose this motor if speed, load-carrying capacity, and rapid displacement are the primary requirements. It is the definitive choice for those who need to cover large bodies of water quickly before the weather shifts.
Honda BF2.3DHSC: Easiest to Maintain
The Honda BF2.3DHSC offers a unique approach to portable power by utilizing an air-cooled system rather than water cooling. This design eliminates the traditional water pump, impeller, and cooling passages, which are notorious for clogging with sand, mud, and salt. It is an exceptionally smart option for shallow estuaries, muddy rivers, and weedy shallows.
Another distinct advantage is the centrifugal clutch, which allows the motor to idle without spinning the propeller. Twist the throttle to engage the prop, and release it to stop, making docking maneuvers and tight-space trolling incredibly precise and stress-free. The lightweight 31-pound build ensures easy transport and mounting.
While the air-cooled design does produce a slightly louder hum than its water-cooled competitors, the maintenance-free peace of mind is an excellent trade. This motor is perfect for shallow-water anglers who want to spend their time fishing rather than cleaning out clogged cooling lines.
Tohatsu MFS20ES: Best EFI Option
The Tohatsu MFS20ES brings modern fuel-injection technology to the portable outboard market without requiring a heavy starter battery. Its battery-less Electronic Fuel Injection (EFI) system ensures quick, reliable starts in freezing weather or high altitudes. This design eliminates carburetor issues entirely, which are the most common source of small-engine failure due to ethanol fuel degradation.
With a weight of 95 pounds, this 20-horsepower powerhouse is designed for semi-permanent installation on robust aluminum utility boats or small skiffs. The twin-cylinder configuration runs exceptionally quiet and delivers smooth, vibration-free trolling at incredibly low speeds. The EFI system also optimizes fuel consumption, squeezing maximum distance out of every drop of gasoline.
This motor is the ultimate match for serious anglers who demand top-tier fuel efficiency and modern starting reliability on larger, heavy-duty fishing boats. If pull-starting a cold carburetor is a chore of the past, this EFI model is the right call.
ePropulsion Spirit 1.0: Best Electric
The ePropulsion Spirit 1.0 Plus redefines portable power with an eco-friendly, virtually silent electric propulsion system. Equivalent to a 3-horsepower gasoline motor, this unit produces zero emissions and requires no gas cans, oil, or winterization. It is an exceptionally clean solution for small spaces where fuel odors are unwelcome.
The crown jewel of this motor is the integrated 1276Wh lithium battery, which actually floats if dropped overboard during installation. The digital display on the tiller provides real-time updates on battery percentage and remaining run time, eliminating range anxiety on the water. Its modular design allows the battery to be easily detached from the shaft for lighter carrying.
While long-distance touring requires planning for recharging cycles, the silent glide is unmatched for stealthy shallow-water fishing. This is the premier option for anglers operating on motor-restricted lakes or storing their gear inside living spaces like RVs and vans.
How to Measure Your Boat for a Short Shaft
Using the wrong shaft length on a small boat leads to poor performance, excessive drag, or engine overheating. A standard short shaft outboard has a length of approximately 15 inches, designed specifically for low-profile transoms. Measuring the boat accurately before making a purchase ensures the propeller sits at the perfect depth.
To find the correct measurement, park the boat on a level surface or trailer and locate the centerline of the transom. Measure vertically from the top edge of the transom board, where the motor clamps down, directly to the bottommost point of the hull keel. This distance dictates the shaft length required to submerge the propeller and cooling inlets properly.
For optimal performance, the anti-cavitation plate (the flat metal wing directly above the propeller) must align correctly with the bottom of the hull. Ideally, this plate should sit even with the lowest point of the boat, or up to one inch below it. If the plate is too high, the propeller will suck in air; if it is too low, the extra drag will slow the boat down.
Keep these key sizing risks in mind: * Shaft too long: Creates unnecessary drag, increases the draft, and risks hitting bottom debris. * Shaft too short: Causes cavitation, loses thrust in choppy water, and can lead to engine overheating from dry water intakes.
Matching Horsepower to Your Boat’s Weight
Overpowering a small fishing boat is a dangerous mistake that can swamp the transom, while underpowering makes navigating currents incredibly difficult. Achieving the right balance requires evaluating the combined weight of the hull, passengers, fuel, and gear. A heavy load demands more displacement power to lift the bow and reach a comfortable planing speed.
As a general rule, small utility boats require approximately one horsepower for every 100 to 150 pounds of total operating weight to move efficiently. However, getting a boat to “plane”‚Äîwhere it glides on top of the water rather than pushing through it‚Äîdemands a higher concentration of power. A heavy hull with a small motor will plow through the water, consuming excessive fuel while traveling slowly.
Distribution of weight is just as critical as the total poundage. A heavy motor on a light transom pulls the stern down, raising the bow and dangerously limiting forward visibility. Selecting a motor that matches both the boat’s rating plate and your realistic payload ensures stable, level tracking.
Use this quick reference guide for proper power matching: * Under 150 lbs (Canoes, small inflatables): 2 to 3.5 HP provides plenty of speed without overwhelming the light transom. * 150 to 300 lbs (Jon boats, small utilities): 5 to 9.9 HP delivers the necessary power to plane with two occupants and fishing gear. * Over 300 lbs (Heavy skiffs, deep-V aluminum): 15 to 20 HP ensures safe navigation in open water and strong currents under heavy payloads.
Storing Your Outboard Motor in Tight Spaces
For those living in tiny homes, RVs, or boats, storing a gas-powered outboard presents unique spatial and safety challenges. Gasoline fumes can quickly overwhelm a small living area, and leaking engine fluids can ruin interior finishes. Managing space constraints requires strict adherence to proper storage protocols.
Four-stroke outboards contain engine oil in the crankcase, which will seep into the cylinders if the motor is laid down incorrectly. Most manufacturers stamp a small graphic on the engine cowl indicating which side must face upward during horizontal storage. Storing the motor on the wrong side leads to oil-soaked spark plugs and costly hydraulic lock.
To eliminate fuel odors and carburetor gumming, always run the engine dry before taking it off the boat. Disconnect the fuel line and let the motor run until it starves itself of gas, ensuring no fuel remains in the lines or carburetor bowl. This simple step keeps living spaces smelling fresh and ensures the motor starts easily next season.
Implement these storage best practices to maximize safety and space: * Use a folding engine stand to keep the motor vertical and minimize its footprint in a closet or shed. * Drain the carburetor bowl manually if storing the motor inside a vehicle to prevent any residual fuel leakage. * Store the fuel tank separately in a well-ventilated exterior compartment or rack to prevent dangerous fume buildup indoors.
Gas vs. Electric: Which is Best for You?
The choice between gasoline and electric outboard motors hinges on how you travel, where you fish, and your tolerance for maintenance. Gas engines offer unmatched range and raw power, making them indispensable for remote expeditions where extra fuel can simply be carried in plastic jugs. However, they demand routine oil changes, spark plug replacements, and winterization.
Electric outboards provide near-silent propulsion, zero emissions, and instant torque without the hassle of pull cords. Because they have no internal fluids or combustion chambers, they can be stored in any orientation without leaking oil or emitting toxic fumes. This clean profile makes them incredibly attractive for tiny home and RV dwellers who must store gear indoors.
The trade-off lies in energy density and recharging logistics. A gas motor can be refueled in seconds, while an electric motor requires access to shore power, a generator, or a robust solar array to recharge its heavy lithium batteries. Anglers must weigh the convenience of silent running against the logistical challenge of off-grid battery management.
Consider this simple framework when making a final decision: * Choose Gas if you fish in strong river currents, travel long distances from charging sources, or require high top-end speeds. * Choose Electric if you fish on protected, motor-restricted lakes, store your equipment inside your living quarters, or prefer low-maintenance machinery.
Finding the ideal short shaft outboard motor is about aligning your boat’s specifications with your unique storage and travel needs. Whether choosing the lightweight simplicity of the Suzuki 2.5, the robust power of the Mercury 9.9, or the clean efficiency of the ePropulsion electric, the right choice will keep you safely on the water for years to come. By prioritizing correct measurements and realistic horsepower, you can confidently embark on your next fishing adventure.
Frequently Asked Questions (FAQs)
What is considered a short shaft outboard motor?
A short shaft outboard motor has a shaft length of approximately 15 inches measured from the mounting clamp bracket down to the anti-cavitation plate. This configuration fits small watercraft with transom heights between 15 and 16 inches, such as aluminum jon boats, tenders, and small inflatables. Installing this motor on a matching transom ensures the propeller sits fully submerged at the correct running depth without creating excessive drag.
What does the cavitation plate do on a short shaft outboard motor?
The anti-cavitation plate on a short shaft outboard motor blocks surface air from getting sucked into the spinning propeller blades during operation. When air reaches the propeller, the blades lose grip, engine RPMs spike, and forward propulsion drops dramatically. Position this flat horizontal plate flush with, or up to one inch below, the lowest point of the boat hull to maintain steady water pressure around the prop.
How do I measure boat transom height for a short shaft outboard motor?
Measure your boat transom by running a tape measure vertically down the center from the top edge to the very bottom of the hull. For a short shaft outboard motor, the distance should fall between 15 and 16 inches. Keep the tape perpendicular to the water line rather than following an angled transom slope. If your measurement reads closer to 20 inches, your boat requires a long shaft motor instead.
How do I break in a new 4-stroke short shaft outboard motor?
Follow the manufacturer ten-hour break-in schedule by varying engine speeds and avoiding sustained full-throttle runs on your new four-stroke short shaft outboard. Run the engine at fast idle for the first 15 minutes, keep it below half-throttle for the next two hours, and run below three-quarter throttle for the subsequent eight hours. Change the crankcase oil and lower-unit gear lube after the first 10 or 20 hours to remove initial metal shavings.
Short shaft vs long shaft outboard: which is better for a shallow water jon boat?
Short shaft outboard motors are better for shallow water jon boats because standard 10-foot to 14-foot jon boats are built with 15-inch transoms. Using a short shaft keeps the lower unit higher in the water column, preventing the propeller and skeg from striking submerged rocks, stumps, or sandbars. Installing a 20-inch long shaft on a 15-inch transom creates extra underwater drag and significantly increases your draft in skinny water.
How much does a new short shaft outboard motor cost for a small boat?
Prices for a new short shaft outboard motor typically range between $900 and $3,500 depending on horsepower, fuel system, and brand. Portable 2.5 HP to 3.5 HP four-stroke models from brands like Tohatsu or Mercury cost between $950 and $1,300. Higher-output 6 HP to 9.9 HP engines with external fuel tanks and electronic fuel injection range from $1,800 to $3,200, while lightweight electric outboards cost between $1,200 and $2,500 without high-capacity batteries.
Why is my short shaft outboard motor cavitating when turning or accelerating?
Cavitation happens when your short shaft outboard motor is mounted too high on the transom, letting air reach the propeller blades under load. Check your motor height so the anti-cavitation plate sits level with the boat bottom. Alternatively, a trim angle set too far out or a nicked propeller blade can pull air downward. Lower your trim pin position by one hole closer to the transom to correct the thrust angle.
Is a short shaft outboard motor safe for coastal bay fishing?
Operating a short shaft outboard motor in coastal bays is safe only in protected waters and calm conditions on boats with 15-inch transoms. Low 15-inch transoms sit close to the waterline, making small fishing craft vulnerable to swamping if a following sea or heavy wake washes over the stern. Anglers should stick to sheltered estuaries, monitor wind forecasts below 10 knots, and carry a manual bilge pump or bailer along with Coast Guard-required safety gear.
