Any given boat will be tagged or engraved with the manufacturer’s maximum recommendation for outboard motor power, based on the craft’s size, weight and structural design. Exceeding this maximum poses a safety hazard and is a punishable offense in some jurisdictions. Any motor of lesser power can be attached to the boat, but speed and performance is proportionally diminished by the motor’s power relative to the weight of the boat.
And 8hp outboard motor is an engine that generates 8 horsepower of energy. They are available in both 2-stroke and 4-stroke designs. The latter design is akin to a small car engine, while the former to that of a motorcycle. Most models employ an extending tiller for steering and accelerating. Many have hydrofoils designed into the shafts to improve the propeller’s thrust dynamic.
The choice between 2-stroke and 4-stroke is mostly a matter of preference and function. If an 8hp outboard motor is the boat’s main propulsion secured to the center of the rear transom, the 4-stroke might be the right choice. It burns fuel relatively quietly, efficiently, and cleanly. Most have an electronic ignition switch to start and stop it.
The generally less expensive 2-stroke motor is smaller and simpler in design. It has better acceleration and more power relative to its weight. A mixture of gasoline and a motor oil additive is required to fuel it. Some models have electronic ignition, but most have starters that are engaged by spring-loaded rip cords. If the 8hp outboard is an emergency backup motor, a “kicker” for stability and drift control, or a separate motor dedicated to trolling fishing lines, this might be the right choice.
The 8hp outboard motor is ideal for trolling both live bait and lures to angle for a variety of fish species. At maximum thrust, even on a 20-foot ocean craft, it can attain enough speed to entice aggressive pelagic predators. It can also throttle down a ski or bass fishing boat to slowly track the contours of a dammed impoundment for suspended schools of panfish.
A boat with a gross weight of a half-ton, such as a small pontoon party boat, is approximately the upper limit of practicality. An 8hp motor will labor to budge a boat this heavy and, in any case, a manufacturer will have specified a minimum power recommendation. For the lower limit watercraft suitable for an 8hp outboard engine, the important factor is not so much the weight of the boat but rather its structural design, especially its hull. The key here is whether the craft is capable of, and stable when, “planing.”
When a boat reaches planing speed, the bow will lift above the surface of the water. As the boat returns to level, the only point of contact becomes the propeller just under the surface. In a real sense, the boat flies. An 8hp outboard motor has sufficient power to push a small craft up to 20 miles per hour and bring it to a plane.
Any watercraft with a V-shaped hull will plane well. An 8hp motor is, thus, the most popular outboard for aluminum johnboats, or dinghies, up to 14 feet (4.27 m) long and weighing up to 300 pounds (136 kg). Round-bottom hulls, such as canoes, are less stable on a plane, and a motor that strong is arguably ill advised.
Boats with flat hulls, such as skiffs, cannot plane. An outboard motor rating of more than 4 horsepower should not be paired with a small skiff. One exception to this rule is the inflatable. Its light weight and buoyancy mean a large inflatable powered by an 8hp outboard motor may perform quite well.
Lastly, for maneuvering dockside and for emergency propulsion, a motorized propeller is essential for sailboats. With their shallow draft hulls, sailboats 25 feet (7.6 m) and more are suited to an 8hp outboard motor. Optimally, the versatile motor is likely to be a perfect fit for most V-hulled boats that best accommodate two passengers and can be carried by two people.