A Complete Guide: Multi vs. Single Outboard

Boat design and power requirements have come a long way in the last 50 years. Outboard motors have progressed from the simple, single-cylinder engines of the past to the modern, multi-cylinder engines of today.

Fishing boats have also evolved, from the small, open boats of yesteryear to the large, multi-purpose fishing boats of today. So, what is the best option for powering your fishing boat? Should you go with single or multiple Yamaha outboards?

Buyers face this question daily, and the choice can be difficult. Of course, some of the considerations will influence the decision more than others. But ultimately, the choice of single or multiple outboards depends on the boat's specific needs and its owner.

Factors to Consider When Choosing Outboard Power

Cost of the Boat Engine

The cost of the boat engine is one of the most important considerations when choosing outboard power. A single outboard motor will typically cost less than half of what a comparable multi-outboard system would cost.

This is because a single outboard only has one engine, while a multi-outboard system has two or more engines. Also, the cost for rigging controls, wiring harnesses, cables, instrumentation, and labor nearly doubled with multi-outboard setups. The same applies to regularly scheduled maintenance.

Boating Safety

A belief exists that having multiple outboards provides a greater margin of safety than having a single outboard. If one engine fails, the other(s) can get you back to shore. This may have been true in the past when outboard motors were less reliable than they are today. But, with the modern-day reliability of outboard motors, this is no longer a valid concern.

In fact, having multiple outboards can create new safety hazards. For example, if one engine fails and the other is still running, the boat will be unbalanced and could capsize. The boat will be difficult to control and is not a true safety measure.

There is no difference in safety between a single and multiple engine setup for an outboard motor. Know about how many hours are too much for an outboard motor.

Boat Speed

Regarding speed, a single outboard should outperform two inboards because the water resistance of a single gear case and propeller is less than that of two. The weight of two small outboards outweighs that of one large motor.

A Yamaha F250 weighs 619 pounds, and a pair of Yamaha F115s has a combined weight of 772 pounds with 386 each. The extra weight can affect the boat's speed, fuel efficiency, and handling.

When you observe the performance of Yamaha boats in real life, you will notice that multi pairs, owing to extra weight, have low speed. But it also indicates that a single outboard might not always be faster than two. The factors such as propping and engine height can affect the performance.

Speed of Hole Shot

With speed, acceleration time is also an important consideration. A multi outboard must achieve a faster hole shot than a single outboard. Because multis have a larger blade area to punch out of the hole, and drag is less of a problem during early acceleration than at higher speeds, they can reach their top speed more quickly.

On the other hand, single outboards have a smaller blade area and, as such, take longer to plane. But once on a plane, they have less drag and can achieve their top speed more quickly than multis.

Fuel Efficiency of the Boat

A single outboard is a way to go if your goal is to maximize fuel efficiency. A multi-engine setup will burn more fuel than a single-engine because each engine must overcome the drag of the other.

When you buy a new boat, you must also calculate the number of hours you will use it. Therefore, fuel efficiency may not be a big concern if you don't use it that often. But, if you plan to use your boat a lot, fuel efficiency should be a major consideration.

In Yamaha's performance testing with the popular 19-foot center console boat, the fuel efficiency of the F250 was about 20 percent better than that of the multi F115s.

Easier Boat-Engine Setup to Use

Maintaining a pair of multi outboards in sync was previously difficult, but technology improvements have made it much easier. Although multi-engine boats come with multi throttle controls, it's now possible to get a single binnacle control that will operate both engines.

Power assist hydraulic steering is also available for multi-engine boats, making it much easier to maneuver the boat. Gone are the days when you required two people to operate a multi-engine boat. The days of fighting with the wheel to turn the motors are long gone. Consequently, multi outboards are no more challenging to manage than a single-engine.

Boat Handling

With outboard lower units that provide an effective pair of directional thrust vectors, the maneuverability race is taken totally by multi engines. A multi-engine boat can spin on its axis like a pinwheel, turn very tightly in length, and back into a slip with ease. All these maneuvers are more complicated with a single-engine boat.

multi gives you the edge when you try to jockey a boat into a tight slip at the fuel dock or when you have to back down on a fish in a crowded marina. Also, because each engine can be operated independently, you can make excellent adjustments to your speed and position.

Conclusion

Weigh all these factors carefully in deciding whether a single or multi Yamaha outboard is right for you. Consider your boating needs and how you will use your boat. If performance is your primary concern, a single outboard is a way to go. If you want the ultimate in maneuverability, choose multis.