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How Much Horsepower Do I Need for My Boat?

Do you want to buy an outboard? The good news in advance: All manufacturers today have mature engines in their program. The market is very competitive and vendors simply can not afford to offer inappropriate models. However, they differ in the details, and so the purchase will be thoroughly considered. Before buying, some basic questions should be clarified:

1. How strong should the engine be?

That depends primarily on the boat. The manufacturers have to indicate with how much horsepower the model may be driven maximum. This depends on the design, the length and of course the stability. Even a minimum specification is usually missing. A big engine is heavy, expensive and consumes a lot of gas.

Nevertheless, the boat should not be motorized too weak. First, this is at the expense of driving comfort, and second, the purchase may even be worthwhile in the long run. A small machine that constantly runs at full throttle at the stop usually consumes more gasoline than a larger model in the medium speed range. Also, engines that are constantly working at the limit wear out faster. Therefore, one should move in the selection in the upper third of the recommended range. However, some boat manufacturers with the highest figures are very cautious, others – especially American vendors – are less modest. Therefore, I strongly advise you to consult a specialist who knows the peculiarities of the boat. If you want to buy your desired outboard motor then you should read our review on it.

2. four- or two-stroke?

The gas-guzzling, smelly and loud two-stroke is a thing of the past. Not least the European emission standard contributed to this. Because of them, many two-stroke engines have disappeared from the market. Two manufacturers have responded to the requirements with direct-injection two-stroke engines. So Evinrude has brought the E-Tec and Tohatsu the TLDi on the market. They are compared to corresponding four-stroke low maintenance. If you put the lever on the table, something happens! The driving pleasure is bought at a higher volume and a certain odor nuisance. Especially with slow driving and tailwind, one occasionally sits in the exhaust fumes. The fuel consumption, the weight and unfortunately also the price, both variants take nothing. So the decision is ultimately a matter of taste. With one exception: If you want to haul or troll a lot, I’d rather recommend a four-stroke. Even with the direct-injection two-stroke engines, the spark plugs grunted relatively quickly. Also, they run on a slow ride comparatively restless. However, it must be said that the engines with the durable Untertertigen driving a lot. This is not without a trace on four-stroke cars. In our trolling engines, for example, we’ve found that over time, gasoline penetrates into the oil, diluting it and thus worsening lubrication. So the ideal towing engine has yet to be invented … Also, they run on a slow ride comparatively restless. However, it must be said that the engines with the durable Untertertigen driving a lot. This is not without a trace on four-stroke cars. In our trolling engines, for example, we’ve found that over time, gasoline penetrates into the oil, diluting it and thus worsening lubrication. So the ideal towing engine has yet to be invented … Also, they run on a slow ride comparatively restless. However, it must be said that the engines with the durable Untertertigen driving a lot. This is not without a trace on four-stroke cars. In our trolling engines, for example, we’ve found that over time, gasoline penetrates into the oil, diluting it and thus worsening lubrication. So the ideal towing engine has yet to be invented …

3. What about the service?

Before making a selection, check the local dealer network. Is there a specialist workshop that can repair my engine in an emergency? Dealers do not have all the brands in the program. If I come with a “foreign brand,” it can be problematic. This is very important especially for warranty cases and complicated repairs. So do not immediately buy the bargain from the Internet, but first, check whether the prescribed maintenance can be carried out on site.

4. Which shaft length do I need?

Please note the shaft length of the motor! They are made with normal shank, long shank and ultralong shank. Which variant you need can be found in the boat documentation, or you can ask your dealer. Otherwise, you run the risk of making a bad purchase. Some notice that only on the maiden voyage, when the engine suddenly takes a breath.

Afterward, I divided the engines according to PS into different classes and described the special features. This gives you a quick overview of the peculiarities and areas of application of the machines.

2 to 6 hp

Previously could be driven up to a power of 3.68 kW (five hp) in the USA without a license. Therefore, the small engines enjoyed great popularity. They are ideal for inflatable boats and smaller boats. Mostly they are quite light and thus quickly attached to a small boat. Now there’s the only four-stroke in the USA since the two-stroke engine does not meet the emission standards. On the second-hand market, however, many two-strokes to get, which may also be traded freely. These are especially interesting because of the lower weight. The slightly higher fuel consumption is hardly negative in this class. But if you tow a lot, a four-stroke engine is better for you. Most engines have built-in tanks, but only one to two liters. Therefore, an external tank should be connectable. This saves us and the environment from refueling on the water. It usually goes something wrong. Often, the engines in this class are single cylinder carburetors. This technique is robust and with some maintenance, you rarely have trouble with the models. It is important to find out exactly about the cold start. Mostly the engine has to be started with the help of a choke and warm up for a few minutes before it can start. When transporting in the trunk, care must be taken to place the engine on the right side. Otherwise, the oil runs out. This technique is robust and with some maintenance, you rarely have trouble with the models. It is important to find out exactly about the cold start. Mostly the engine has to be started with the help of a choke and warm up for a few minutes before it can start. When transporting in the trunk, care must be taken to place the engine on the right side. Otherwise, the oil runs out. This technique is robust and with some maintenance, you rarely have trouble with the models. It is important to find out exactly about the cold start. Mostly the engine has to be started with the help of a choke and warm up for a few minutes before it can start. When transporting in the trunk, care must be taken to place the engine on the right side. Otherwise, the oil runs out.

The smallest outboards start at 2.5 hp. These small power plants weigh between 12.4 and 18 kilograms and are either air-cooled (Honda) or water-cooled.

The 4.5-and-6-horsepower engines consist of identical engine blocks for many manufacturers, which were installed only different carburetors, which bring more or less power. For whom the weight does not play such a large role, which should consider the purchase of a larger two-cylinder engine. These six to 15 hp engines can be throttled and thus drive without a license. They score with high smoothness and pulling power. The latter allows even with throttled engines, the installation of a larger thrust propeller. So even with license-free engines for larger boats, good results can be achieved. The smallest two-cylinder Yamaha has with its 6/8-PSER in the program. Until recently, Honda also had a 6-hp two-cylinder engine on the market. This engine is very robust

8 to 30 hp

In this class, many boat owners move with companions from 3.5 to 5 meters. With an engine of 15 to 30 hp, you can reach speeds of up to 20 knots, depending on the size of the boat and the load. In recent years, quite a few new models in this class have been launched by most manufacturers. I particularly like the light and compact Honda engines with eight to 20 hp. But also Yamaha has a rich selection in the field. Mercury has very robust engines on offer. For those looking for a good cold-start performance,
a direct-injection engine like the Mercury 25/30-HP EFI is well-advised. Turn on and drive off is the motto here. Competitors in this class only offer carburetors that need to run a bit warm.

40 to 60 hp

Anyone who regularly drives to a large lake or the sea and is the proud owner of a boat 4.5 to six meters long, needs a powerful engine. Most models have 800 to 1200 cubic centimeters and three to four cylinders. Depending on the manufacturer, the weight varies between 94 and 112 kg for a 50 hp engine. The Honda is the lightest and even beats the two-stroke Evinrude and Tohatsu. With the Suzuki 50 hp, I have had very good experiences. For five years this was mounted on one of our guiding boats of the team Bodden-fishing. Since he was in extreme conditions in summer and winter in use. He performed 3,900 operating hours without major problems. That’s about 50,000 kilometers on the water. Today he is not broken but is still running in private hands. An average user rarely gets more than 100 hours of operation a year. The engine should, therefore, keep the whole life with appropriate maintenance and the associated oil changes.

A special feature of this class is the already mentioned two-stroke models by Tohatsu and Evinrude. They score especially regarding torque. These engines are very low maintenance and sometimes consume even less fuel than the four-stroke engine. This is especially the case in the lower speed range. However, they are not fully suitable for frequent trolling missions. The oil in the exhaust gases also leads to an odor nuisance. Here decides the personal taste.

Also noteworthy is the Suzuki 60 hp engine, which is the largest 60-horsepower engine with a displacement of nearly 1300 cc. As far as the performance is concerned, he does not have to shy away from the comparison with a 70- or 80-hp engine. However, the weight is quite high at 149 kilograms.

70 to 150 hp

Engines of this strength usually power larger boats over six meters. This area is considered a prestige class, in which the manufacturers must not be naked. Accordingly, one obtains consistently sophisticated, reliable models. At prices of up to $17000 you can expect that too. It is fair to say, however, that they have a high life expectancy and rarely technical problems. Depending on the manufacturer, they have a displacement of around 2,000 cubic centimeters and weigh between 130 and 230 kilograms. In the four-stroke, all engines are equipped with modern electronic direct injection systems. Suzuki and Mercury rely on displacement, Honda on the innovative, speed-oriented V-Tec technology. Very popular and often seen is the 140-hp Suzuki, which was developed on the basis of the 115-horsepower engine. It impresses with a lot of power and comparatively low weight. Worth mentioning is the Verado from Mercury, with which the com press technology was introduced to the boat engines. However, the consumption levels in tests were quite high. Evinrude and Tohatsu also have modern two-stroke engines in this class.

Over 150 hp

These engines are rare on fishing boats, so we do not consider them in our overview table. The mission is likely to be limited to larger trolling yachts beyond seven meters. There are sometimes even two large engines operated side by side. The currently largest outboard comes from Yamaha and makes 350 hp. It has 5330 cubic centimeters, eight cylinders and weighs 365 kilos. There are several 300-horsepower engines. There would be, for example, the 300-hp Suzuki with 4028 cubic inches of displacement, six cylinders and 274 kilos. Also a considerable chunk! Evinrude also has a two-stroke on the market here. What this E-Tec releases in terms of torque and power is enormous. There should really be left only an experienced boat driver behind the wheel. Whether such engines are reasonable? Of course not! They cost about the price of a good compact car and I’m no known anglerischer use, which requires these caliber mandatory. But it’s fun to be so fat
To drive machines!

Please note!

Where wood is chopped, splinters must fall. So there are problems with the outboards again and again. With so much electronics and the sometimes very hard use, this is no wonder. The engines are built to protect themselves from major damage. Too little oil or lack of cooling water are the most common causes of failure. Alarm signals and red lamps warn against it. In addition, many engines have emergency programs. As soon as a damage occurs, the machines can only drive at low speeds and thus can no longer be overloaded. Thus, a total loss is avoided and at the same time ensures the return home to the port. Once there, you should visit a workshop as quickly as possible.

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