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Engines

Which Engine Brand should I choose?

Firstly let’s make it clear that all the major outboard engine manufactures produce excellent products. At Wills Marine we specialise…

Firstly let’s make it clear that all the major outboard engine manufactures produce excellent products.

At Wills Marine we specialise in the following three internationally respected brands Evinrude, Mercury and Yamaha,.

Evinrude

Ole Evinrude is credited with the invention of the outboard engine. It was a single cylinder water cooled 1.5hp unit and following its introduction in 1909 was an immediate success.

More recently Evinrude were delighted to announce the introduction of their second generation E-TEC G2. These outboards were developed in conjunction with the University of Wisconsin using state of the art combustion analysis software.

The Evinrude E-TEC was the first outboard engine technology to win the American Environmental Protection Agency 2004 Clean Air Excellence Award, and all our Evinrudes remain fully compliant with current emissions regulations. In addition they offer superior fuel efficiency, no scheduled dealer service for 3 years, excellent torque & acceleration characteristics and are of course light in weight.

We keep a wide range of Evinrudes in stock for immediate fitting to your boat.

Mercury

Mercury offers a good range of smaller engines which we can normally supply from stock.

Small and portable, the Mercury range provides smart, simple-to-use features plus clean, quiet, fuel efficient four-strokeperformance makes them the obvious choice in engines up to 20hp.

Yamaha

Marine technology has moved on tremendously in recent years and Yamaha have been at the forefront of this innovation. Yamaha engineers and commercial staff share the passion of the millions of Yamaha customers, listening to what they have to say and understanding how their products are used.

Whether it is a fisherman in Indonesia or a family on the Norfolk Broads, a Yamaha outboard motor will be a reliable partner that meets their boating needs - with a worldwide support network which has been developed and matured since 1960.

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What size outboard will be right for my boat?

Here are some things to consider. Suitability for use If you want to potter around the estuary in a small…

Here are some things to consider.

  • Suitability for use
  • If you want to potter around the estuary in a small boat then you can choose the minimum size of engine recommended by your boat manufacturer. If you want the boat to 'plane'(skim along the surface at close to horizontal aspect) then you will need more power so you will need at least 6hp, even for an inflatable and of course more for a traditional fiberglass boat. If you want to waterski then you will need to get over 20 mph and will need at least 25hp, even in a relatively lightweight boat.
  • Suitability for your boat
  • Usually you will have a range of size choices for your boat up to a maximum that is dictated by weight. If you are buying a Grand RIB for example the manufacturer will specify a recommended range of sizes you can consider.
  • Ability to carry
  • Outboard engines are awkward to carry and you probably won't want to carry anything above 10hp on your own and even a 4hp engine starts to weigh heavy if you have a bad back or have to go up steps or any distance to your car on your own. Remember that for any given horsepower 4 stroke engines are usually a lot heavier than 2 stroke.
  • Ability to transport

This of course depends on the size of your car boot but a mid size car will probably take up to 15hp and an estate car might take up to 40hp, although handling such a heavy engine will make it awkward. Remember that 4 stroke engines can only be laid down one way, otherwise the oil will empty from the sump with potentially disastrous consequences all round!

CHOOSING THE RIGHT SHAFT LENGTH

This is dictated by depth of your boat's transom, as measured from top to bottom in the centre. If your boat is about 15"-16" you will need short shaft and if it is 20"-21" you will require long shaft. Small inflatables and dinghies tend to require 'short shaft' whilst larger boats usually require long or ultra long shaft. Auxiliary engines for yachts usually require long shaft. We are often asked if shaft length is really critical when people are changing boats and want to keep their existing engine. There's no doubt about it, you must have the right length for the engine to operate efficiently and safely.

CHOOSING THE RIGHT FUEL

Diesel outboards don't really exist and electric engines lack power and require a big battery. They are sometimes used on lakes but we don't recommend them for the estuary or open sea. All petrol engines run on regular unleaded fuel. Incidentally, fuel will go stale so get rid of it at the end of the season. The only exception to this is where you have a large boat with an integral on board fuel tank(for example on one of the larger Grand Ribs), in this case there is an additive that can be used to maintain fuel condition.

MATCHING THE ENGINE COLOUR

Not the most important factor when choosing an engine but Mecury engines are Black, Johnson are white and Evinrude Etec offer the choice of white or the graphite colour scheme which is new for 2015.

Our new Grand RIB's and Nordkapp sportboat packages are colour co-ordinated using the latest Evinrude Etec colour schemes.

CHOOSING BETWEEN 2 STROKE OR 4 STROKE

Everyone asks and everyone has an opinion! With the emissions control legislation in effect since 2007 all new outboard engines must comply with the standards set by the Environmental Protection Agency.

Since carburetted 2 stroke engines were traditionally less environmentally friendly these are now only available for commercial applications.  But there are some very real advantages in 2 strokes and manufacturers have made huge steps in direct injection 2 stroke technology to match and now vastly exceed the advantages of 4 strokes, so the choice now is for 4 stroke engines from 2.5 to 20hp, with 25hp and above direct injection 2 stroke. Contact us or call us on 01548 852424 and we can talk you through the options.

  • The argument for 2 strokes is as follows

They are usually lighter, which is an advantage in terms of power to weight ratio. Since boats have horsepower and engine weight limits it may mean a more powerful engine can be fitted to the boat.

They are somewhat easier to handle. 2 strokes are quite forgiving in terms of handling but 4 strokes are best kept upright and can only be laid down one particular way. This sounds easy but the day will come when someone else does this for you and gets it wrong…with disastrous consequences!

2 stroke offers faster acceleration, which is great if you want to water ski or you are a speed freak!

2 stroke engines are much less expensive to run and maintain. The new generation Evinrude Etec outboards have 3 or 5 year dealer service schedules and are more economical than the equilivent 4 stroke and with less emmissions the greenest outboards available!  

  • The argument for 4 strokes is as follows

There is no argument.

SINGLE OR TWIN RIG

The modern outboard engine is very reliable and for inshore boating a single main engine with a small auxillary is quite adequate and a lot cheaper in terms of initial purchase and ongoing servicing. However, if you are in the habit of going a long way offshore on your own you may consider it prudent to have twin engines if you have the space on the transom, or at least an auxiliary to back up your main engine.

If you are choosing twin rig remember that the props must counter-rotate, otherwise you will be fighting to keep the boat in a straight line.

REMOTE CONTROL

Tiller steering control is almost universal on smaller engines but manufacturers do offer conversion kits, but they're expensive to buy and install. From about 10hp manufacturers offer the option of tiller control or remote steering (using a driving wheel like a car). You can operate a boat on tiller steer up to about 40hp although we do not recommend children operate tiller steering outboards above 10hp, especially if they are going to go flat out. Another factor to consider is that if the boat is tiller steer then the weight of a larger engine, plus battery, plus fuel and of course plus you is going to weigh down the rear of the boat and make it more difficult to control and get on the plane. In much larger size engines remote control is the only way to go and you may also require hydraulic steering above 115hp.

HYDRAULIC STEERING

This is a personal choice but we believe that hydraulic (power) steering isn't essential up to 100hp. Above this the need becomes increasingly obvious and at 150hp and above probably essential. Installed cost will be between £500 and £1000. It's expensive but the difference is very much like power steering on a car, once you've had it you won't want anything else!

MANUAL OR ELECTRIC START

Smaller engines are all manual pull but from about 15hp you can get electric start. The bigger the engine the more effort required and this will be a real limitation for children, the less energetic and anyone with a back problem. Remember, you are doing this at the back of a boat, possibly in choppy water, so you don't have a nice stable platform on which to work!

POWER TRIM AND TILT

Every time you moor up, or when you want to remove your boat from the water you will have to 'tilt' the engine. This usually requires flicking a release switch and pulling the engine forward until it clicks into the raised position. If a boat is left with its engine down when the tide goes out it may cause considerable damage, so this is not a matter of choice. This process is quite easy up to about 10hp but gets increasingly difficult thereafter and once again depends on age, agility and fitness. By the time you get to 25hp the engine is quite a lump to raise manually so you should definitely consider power trim and tilt, which does all the above for you electronically and hydraulically. In summary, for 20hp and above we think that most people will be most comfortable with remote steering, electric start, and power trim and tilt. On manufacturer's specification and price lists this is often abbreviated, for example as 'TL', which means electric start, power trim and tilt, generally on remote control although also available on 25/30hp tiller control motors.ave a nice stable platform on which to work!

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Why are all small outboards 4-stroke configuration?

It is quite simply because this is the lowest manufacturing cost option that meets the emission regulations. Whilst Evinrude have…

It is quite simply because this is the lowest manufacturing cost option that meets the emission regulations.

Whilst Evinrude have developed highly successful outboard designs based on the 2-stroke philosophy the cost of incorporating this technology in the 2.5 to 20hp range would make these engines rather expensive.  It would be quite feasible to manufacture a small 2-stroke that would meet the emissions regulations but the cost of the associated fuel injection equipment and dry sump lubrication system would make them significantly more costly to produce. High-tech 2-strokes also have a relatively high compression ratio and this means a little extra muscle would be needed in order to hand start them.

Small 4-strokes can be designed to meet emissions regulations using a relatively low compression ratio, wet sump oil lubrication and a carburettor fed inlet manifold. They are a little heavier that the old 2-strokes due to the valve gear but gone are the days of blue smoke every time you started them.

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What fuel should I use in my outboard?

Well, Diesel outboards don't really exist and electric engines lack power and require a big battery; they are sometimes used…

Well, Diesel outboards don't really exist and electric engines lack power and require a big battery; they are sometimes used on lakes but we don't recommend them for the estuary or open sea, so we are left with gasoline or petrol as it is known in the UK.

All petrol engine outboards, both 2-stroke and 4-stroke run on premium unleaded fuel.

Incidentally, fuel will deteriorate over time. The most volatile components may evaporate depending on the storage conditions and this may lead to issues with starting at the beginning of the new season. It therefore pays to use up as much of the old fuel as possible prior to laying up.

Where you have a large boat with an integral on board fuel tank (for example on one of the larger Grand Ribs); in this case there is an additive that can be used to maintain fuel condition.

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Do I need a Short or Long Shaft Outboard?

The correct length for the outboard engine drive shaft is determined by the height of your boat's transom, as measured…

The correct length for the outboard engine drive shaft is determined by the height of your boat's transom, as measured from top to bottom in the centre. This distance is generally referred to as the “Transom Height”

If your boat has a Transom Height 15"-16" you will need short shaft and if it is 20"-21" you will require long shaft engine.

Small inflatables and dinghies tend to require 'short shaft' engines whilst larger boats usually require long or in some cases special ultra long shaft versions.

Auxiliary engines for yachts usually require a long shaft engine so as to make sure the propeller remains well submerged when the boat is in a seaway.

We are often asked if shaft length is really critical when people are changing boats and want to keep their existing engine. There's no doubt about it, you must have the right length for the engine to operate efficiently and safely.

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Should I Buy a Two Stroke or Four Stroke Outboard Engine?

All the major outboard manufacturers claim their products are superior and each brand offers a unique technological slant that seeks…

All the major outboard manufacturers claim their products are superior and each brand offers a unique technological slant that seeks to put its products above the competition. Of course, they would do that wouldn’t they? So our job is to put the plain facts in front of customers in order that they can make an informed choice.

For engines of 25hp and up the primary decision will be between the two and four stroke configuration, so what’s the essential difference?  The two/four stroke terminology refers to the number of strokes the piston makes to complete a single power cycle. Both two and four-stroke engines are based on the same thermodynamic principles of combustion but are engineered very differently. Each has its advantages and disadvantages.

Historically two-strokes were said to be a bit noisy, had poor performance at speeds below 1000 rpm, were not very fuel efficient and had relatively high emissions. On the other hand they were very responsive, fast, powerful, light and simple to maintain. Four-strokes were heavier than two-strokes, less responsive off the starting line, more complicated and more expensive to maintain. However they were generally quieter than two-strokes, more fuel efficient and had better emissions characteristics. Whilst all these statements applied to a greater or lesser extent the position today is very different.

So, what’s changed?

The answer is quite a lot but one area in particular is responsible for the very substantial improvement in performance and emissions control. In order to obtain high efficiency combustion within the cylinder and minimize emissions it is important to very accurately manage the air/fuel ratio that enters the cylinders for combustion. It needs to be as close to what’s called the stoichiometric ratio as possible, that’s about 15 parts of air to 1part of fuel. In the past the carburetor was responsible for maintaining the air/fuel ratio and in smaller outboards these will still be found. However for larger, (25hp +) high performance engines the solution has been to use programmed electronic fuel injection. However to work at the kind of speeds these engines run at needed a sophisticated control system and hence the introduction of the microprocessor controller. This allowed environmental conditions such as air temperature and pressure together with the conditions experienced within the engine to be monitored in real time and thus to inject precisely the correct amount of fuel to achieve complete combustion over a range of engine speed and load conditions.

This was the breakthrough and it was first fitted to outboard motors in the late 1990s, to be frank…… with varying degrees of success. The good news is that over the past 20 or so years these marine based systems have been developed and improved and are now highly reliable and efficient pieces of kit.

So far so good but for two strokes there was another issue to deal with, that of the need to mix oil with the fuel. The reason for this was that in a two stroke the crankcase formed part of the air/fuel induction process so having lubricating oil mixed with the fuel was a convenient way of getting lubricating oil to the crank shaft, small end bearings and cylinders. However, the resulting blue-tinged combustion products were a feature of this process, especially at start up. Fuel/oil ratios reduced from 25:1 in the 1960s to 100:1 in the 1990s but as long as it was necessary to mix oil with the fuel two strokes were never going to meet the 2006 emissions regulations. So something had to go and that was the oil. The solution was the introduction of dry sump lubrication, a process in which lubricating oil is fed under pressure to the bearing and cylinder surfaces. Job done!  

Evinrude introduced the E-Tec system in 2003. In 2004, they received the EPA Clean Air Excellence Award for their outboards utilizing the E-Tec system.

Yamaha also has a high-pressure direct injection (HPDI) system for two-stroke outboards. It differs from the E-Tec direct injection system because it uses a separate, belt driven, high-pressure, mechanical fuel pump to generate the pressure necessary for injection in a closed chamber.

So, with both two and four stroke outboards able to meet the emissions regulations it really comes down to individual preference. For many people the thing that tips it towards the two stroke is the matter of engine weight. For a given hp the less weight there is hanging off the transom the better.

Looking at engines in the 90 to 150hp range we see that:-

Mercury 100 (four-stroke)   163kg, 150 (four-stroke)   206kg

Yamaha F90 (four-stroke)   167kg,  150 (four-stroke)  218kg

Evinrude E-Tec 90 (two-stroke) 148kg,  150 (two-stroke) 190kg

The Evinrudes come with quite a significant saving of between (15kg and 19kg for the 90hp and 16 to 28kg for the 150hp units) compared to the Mercury and Yamaha units.

outboard engine performance graph

On another practical note comparing performance information between two and four strokes throws up some interesting information.

From the graph opposite “Comparison of 150 HP Outboard Motors from Published Data” we see that for a given rpm the Evinrude two stroke engine has a higher output than either of the four stroke units. That’s not surprising really because the two stroke produces power on every stroke whilst the four stroke produces power every other stroke so we would expect to see such a difference.

Fuel economy is a tricky one but we can compare engines at wide open throttle setting with the following results:

Mercury 100 (four-stroke)  37.9 litres/hr  

Mercury 150 (four-stroke)   58.6 litres/hr 

Yamaha F90 (four-stroke)   34.4 litres/hr 

Yamaha150 (four-stroke)  58.6 litres/hr 

Evinrude E-Tec 90 (two-stroke)   29.1 litres/hr 

Evinrude E-Tec150 (two-stroke) 57.0 litres/hr 

So, what does all this mean in practical terms? Well based on this analysis we can say that, for a given power output two-strokes appear to be significantly lighter with a higher output level throughout the rev range.

At wide open throttle the two stroke also appears to have a small advantage in terms of fuel consumption.

Hope you found this useful!

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Can I match my engine to the boat’s colour scheme?

The answer is yes, you can now! Though perhaps not the most important factor when choosing an engine but the…

The answer is yes, you can now!

Though perhaps not the most important factor when choosing an engine but the new Evinrude E-Tec G2 engines (200-300 hp) recently upgraded with further enhanced performance are now available with five colour co-ordinated options to match any boat!

Meanwhile, Mercury engines are Black, Johnsons are white and the smaller Evinrude E-Tecs offer a choice of a white or a graphite colour scheme.

Our new Grand RIB's and Nordkapp sportboat packages are also colour co-ordinated using the latest Evinrude E-Tec colour schemes.

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What about other engine options and arrangements?

SINGLE OR TWIN RIG? The modern outboard engine is very reliable and for inshore boating a single main engine with…

SINGLE OR TWIN RIG?

The modern outboard engine is very reliable and for inshore boating a single main engine with a small auxiliary is quite adequate and a lot cheaper in terms of initial purchase and on-going maintenance. However, if you are in the habit of going a long way offshore on your own you may consider it prudent to have twin engines if you have the space on the transom, or at least an auxiliary to back up your main engine.

If you are choosing twin rig remember that the props must counter-rotate, otherwise you will be fighting to keep the boat in a straight line.

REMOTE CONTROL?

Tiller steering control is almost universal on smaller engines but manufacturers do offer conversion kits, but they're expensive to buy and install. From about 10hp manufacturers offer the option of tiller control or remote steering (using a driving wheel like a car). You can operate a boat on tiller steer up to about 40hp although we do not recommend children operate tiller steering outboards above 10hp, especially if they are going to go flat out.

Another factor to consider is that if the boat is tiller steer then the weight of a larger engine, plus battery, plus fuel and of course plus you is going to weigh down the rear of the boat and make it more difficult to control and get on the plane. In much larger size engines remote control is really the only way to go and you may also require hydraulic steering above 115hp.

HYDRAULIC STEERING?

This is a personal choice but we believe that hydraulic (power) steering isn't essential up to 100hp. Above this the need becomes increasingly obvious and at 150hp and above probably essential. Installed cost will be between £500 and £1000. It's expensive but the difference is very much like power steering on a car, once you've had it you won't want anything else!

MANUAL OR ELECTRIC START?

Smaller engines are all manual pull but from about 15hp you can get electric start. The bigger the engine the more effort required and this will be a real limitation for children, the less energetic and anyone with a back problem. Remember, you are doing this at the back of a boat, possibly in choppy water, so you don't have a nice stable platform on which to work!

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Should my outboard have with Power Trim and Tilt?

Every time you moor up, or when you want to remove your boat from the water you will have to…

Every time you moor up, or when you want to remove your boat from the water you will have to 'tilt' the engine. This usually requires flicking a release switch and pulling the engine forward until it clicks into the raised position. If a boat is left with its engine down when the tide goes out it may cause considerable damage, so this is not a matter of choice. This process is quite easy up to about 10hp but gets increasingly difficult thereafter and once again depends on age, agility and fitness.

By the time you get to 25hp the engine is quite a lump to raise manually so you should definitely consider power trim and tilt, which does all the above for you electronically and hydraulically. In summary, for 20hp and above we think that most people will be mote comfortable with remote steering, electric start, and power trim and tilt. On manufacturer's specification and price lists this is often abbreviated, for example as 'TL', which means electric start, power trim and tilt, generally on remote control although also available on 25/30hp tiller control motors.

 

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