While it is important to match the proper-sized large outboard motor to a boat, it is just as important to match the proper-sized boat to a 4hp outboard motor. The 4hp outboard may seem too small to use as a primary motor on a boat, but for some types of craft, it is just right. Many canoes have a flat stern that is designed for an outboard motor, and in this type of craft, the 4hp outboard is a perfect match. It will not overpower the canoe, yet it can save much paddling especially if going against the current. Other vessels, such as certain inflatable boats, small dinghies, sail boats and Jon boats, also can be the perfect match for a 4hp outboard.
By mounting a 4hp outboard on a small inflatable watercraft, the vessel is provided with a power unit that makes going against the current a much more pleasurable endeavor than attempting to paddle or row the boat back to port. If using a small Jon-boat type craft to fish, the small 4hp outboard is the ideal size to troll baits in search of fish. It also allows a fisherman to venture farther out than paddling would allow without becoming too tired to fish. When using a canoe to trek into the back country for a camping expedition, mounting a 4hp outboard on the canoe allows the users to load much more gear into the canoe than could be comfortably hauled by paddling. The small motor will also require a much smaller fuel tank than a larger outboard, thereby taking up less cargo area by using a smaller fuel tank.
There is also a very logical reason to use a 4hp outboard on a much larger boat. While the small outboard is a perfect primary power unit on a smaller craft, it can be just as useful as a backup or reserve trolling motor on a much larger craft. Many fishing boats use outboard motors that are much too large to be used in a trolling capacity. The large motors will not run smoothly at very slow speeds and often overheat due to the failure of the water pump to move the proper amount of coolant at such slow speeds. By using the small outboard as a kicker motor, the boat is able to troll all day without overheating or fouling out spark plugs in the larger motor.