How to choose the right boat engine?

Choosing your boat engine is not easy. What type of power supply will work best: electric or thermal motor? It all depends on the use you plan to make of your boat. Then choose between an inboard motor (inside the hull) or an outboard (outside, on the rear deck). Without forgetting the power which must be adapted to your activity, to your needs, to the weight of the boat. Side brands, the choices are vast but remember to check that there is a dealer near your home port. It is convenient for maintenance and possible repairs. And then, you must know what type of motorboat will suit you best.

What are the different types of engines?

There are two main types of boat engines: heat engines and electric motors. Your choice will depend on the use you want to make of your boat. Be aware that there are more and more places where heat engines are prohibited.

The electric motor

The electric motor has certain advantages. Quiet, clean, odorless, it requires little maintenance, and its operating cost is low, whether for propulsion or maintenance. It can also offer some energy independence with rechargeable batteries.

The energy source is formed by electric accumulators, batteries. It is therefore necessary to come and recharge regularly in a port.

There is no fuel tank but batteries which can be quite bulky depending on the engine power. The recharge time is necessarily longer than just filling up with gasoline.

Autonomy is an essential criterion, but it depends a lot on the use you plan to make of your boat. Nothing prevents you from planning a backup battery.

Lithium batteries are light and practical, but expensive; open leaded ones are inexpensive but be careful with the complete discharge. Gel batteries have a shorter lifespan. This type of engine must be chosen according to the weight of the boat, the weight of the equipment on board, the weight of the passengers and the length of the boat. It can be installed at the bow, on the transom or on a base.

As a rule, the electric motor is mostly suitable for boats under 3 meters, but manufacturers are constantly improving their offer.

It is a perfect engine for those who are environmentally conscious, who like calm, cover short distances and for whom speed is not a priority.

The heat engine

The heat engine is generally more powerful than the electric motor, but its efficiency is less good. It is suitable for navigation in waters with strong current, for large boats, for long distances or for going fast.

It will have a shorter lifespan than an electric motor and noise pollution is often significant.

The heat engine can be two or four-stroke. Two-stroke engines require an oil / gasoline mixture while for four-stroke engines oil and gasoline are separated, allowing the oil to be recycled. These are less polluting because they do not release oil into the air or into the water. However, the maintenance of a four-stroke engine is more important, and its weight is more substantial.

Outboard motor or inboard: which one to favor?

The inboard engine is placed in the hold or in an engine room. Transmission, rudder, and various equipment are in the hull and under the boat. It can be a gasoline, diesel, single-engine, or twin-engine engine. The inboard engine can be combined with different propulsion systems (shaft line, Z-Drive, Sterndrive, IPS, Zeus).

The outboard motor is a compact rear mounted motor with transmission and propeller. It acts as a rudder.

It all depends on the type of boat you choose, its size, the navigation program.

Outboard motor

The outboard motor is mounted on the cross member of the boat, outside the hull and aft. When it is not working, it can be lifted out of the water. This limits corrosion and dirt, allowing navigation in both fresh and salt water. The maneuvers are facilitated because the engine is pivoted on its assembly to direct the thrust of the propeller. Power ranges from 2.5 to over 350 hp.

This type of motor is perfect for small boats but is not suitable for boats that are flush with the water because the anti-ventilation plate should be just on the surface.

It offers ease of maneuvering and maintenance.

Outboards are generally four-stroke gasoline engines (cleaner than the two-stroke engine but, with direct injection, the two-stroke engine becomes less polluting while remaining efficient).

For small boats, whether open, semi-rigid or helmsman, outboard motorization is perfectly suited because it is more economical, easy to maintain and to transport.

For larger boats, outboards may be suitable for open hulls like Fishing or RIBs, inflatable boats, canoes and tenders.

Even for boats of more than seven meters, this engine is increasingly appreciated because it facilitates transport on trailer and allows to choose the power adapted to the navigation program at the time of purchase. Size and power of outboard motors keep increasing while having more and more sophisticated piloting aids systems, not to mention the aesthetics which also evolve.

The inboard engine

With an inboard model, the engine and transmission are mounted inside the hull. The driveshaft passes through the hull. A propeller is attached to it to provide propulsion. The maneuvers are done via a rudder. It works a bit like a car engine adapted to the sea.

There are different types such as the Hydro jet with turbine instead of the propeller for fast boats or the perfect swivel pod for speedboats. The shaft line is the oldest propulsion system with the propeller installed at the end of a shaft linked to the motor in a straight line. The V-Drive allows the engine to be pushed back, especially for water skiing, while the Z-Drive combines the advantage of the base and the inboard.

Inboard engines are recommended for medium speed boats but are more difficult to maintain.

These are heavy engines that run on diesel, but torque remains available at all speed ranges. As it is installed at the bottom of the hold, its center of gravity generates less pitch and offers greater maneuverability. Autonomy is important and the engine can run at high speeds for long periods. The service life is also greater. However, maintenance is more restrictive, and it remains noisy.

It is a good solution for habitable boats like speedboats or helmsmen or if the annual navigation time is important.

The different engine powers

To choose the right power, it is essential to know the total weight of the boat and its dimensions. In the weight, it is necessary to include that of the passengers, the material, the fuel, the batteries, the various material. For a boat sailing often loaded, it is advisable to approach the maximum power authorized by the manufacturer. If the engine lacks power, it will run too hard, resulting in higher fuel consumption and higher maintenance costs. If it is too powerful, the maximum safe speed may be exceeded. A less powerful engine may be sufficient if you are still sailing light.

The CV or horsepower correspond to the administrative power. This is calculated according to the number of cylinders in the engine, the bore, and the stroke. To know the power required, you must consider the weight of the loaded boat. When we talk about a 50 HP boat engine, 150 HP boat engine or 200 HP boat engine, it is really the engine displacement.

For an electric motor, the power measurement is given in English pounds (lbs.) or Kw. It is a thrust that can vary from 45 to 214 lbs. or from 3 or 4 HP to 9.9 HP for the most powerful. There are motors with a power ranging from 30 lbs. to over 100 lbs. for motors that operate at 36 Volts.

There are 24- or 36-Volt motors which are ideal for boats over 500 kg.

But power is not everything. You also must consider the propeller, shaft line and other essential “details”.

In any case, be aware that the delivery of your engine is often free.

Which motorboat to choose?

There are many categories of motorboats. The choice is made according to the use you want to make of your boat.

The cabin cruiser

The cabin cruiser allows you to spend several nights on board for small cruises. The engine can be inboard or outboard.

The open hull

The open hull, with open deck plan, has no living space or cabin. The engine is generally outboard. It is ideal for daytime coastal navigation.

The Day cruiser

The day cruiser has a front deck, a small cabin, an outboard or inboard motor. It allows coastal navigation with the possibility of spending one or two nights on board.

The Dinghy

The dinghy is a small open pleasure boat with an outboard motor for daytime coastal cruising.

The Fishing

The fishing is a boat for sport fishing, big game fishing. It can have a cabin, is comfortable for several nights on board. It is equipped with an outboard motor.

The Jet-boat

The jet boat , propelled by water jet ejected from the back of the boat, is very fast, sporty and easy to maintain. It is a hydro jet engine for sport navigation and the practice of water sports.

The motor yacht

The motor yacht has several decks and a luxurious layout (swimming pool, jacuzzi, swim platform…) for several people. The inboard engine is essential for long-term offshore navigation.

The offshore

The offshore is a powerful racing boat with inboard engine. It is designed for competition and speed.

The fishing trip or the helmsman

are equipped with a wheelhouse for the cockpit, bed, small kitchen, WC… with large cockpit aft for fishing. They are propelled by an inboard or outboard motor and are perfect for fishing and small coastal cruises.

The inflatable and the semi-rigid

have an outboard or inboard motor for large models. The smaller ones are often used as annexes. The larger ones are suitable for coastal navigation and short cruises, in sheltered basins as well as at sea.

The Runabout

The runabout is a very fast motorized dinghy with windshield and an often decked bow with inboard or outboard motor for fast coastal navigation.

The Trawler

The trawler is a travel boat for long trips at low speed. Very comfortable for a long life on board, it is equipped with an inboard engine.

The cruiser

The cruiser is livable and comfortable with several versions: open, flybridge , hard-top. We opt for an inboard engine for offshore cruises.

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