When choosing a diesel or gasoline engine, you need to know not only the size and type of vessel, but also how, where, why and with what intensity it will be used.
It's simple: if you've got a fast gliding boat up to 35 feet, you definitely need gas. If you have a displacement boat or a large gliding boat, a diesel is a more interesting option.
Each one of them...
If your choice has fallen on a small gliding boat where weight matters, the petrol engine is definitely the most logical complete set.
If a diesel engine is installed on such a boat, it will be possible to sail it no more than 2000-3000 rpm without an opportunity to go to the glider and develop at least some decent speed. This is a particular sin for Europeans, who have nowhere to go for a garza, and there is no need to - a small boat at sea will not cut the wave, and the lakes are not the scales and distances to accelerate. They do not need maximum speed, they have other tasks. It's like the Mercedes s-class with a three-liter diesel engine: beautiful, statuesque, but very economical and slow. You can, of course, original and set something like the Volvo Penta D11 at nine metres. On the glider, of course, he will throw the boat, and even the speed will develop a decent. Only its weight and dimensions, which are twice as large as those of gasoline with similar characteristics, will become too heavy a ballast for a lightweight boat. Without logic, any originality becomes a foolishness and a waste of money. That's why for owners of small gliding boats, who are happy for speed, the question of choice is not developed. It is definitely gasoline.
And here comes the nuances and personal preferences.
On any disposable boat it makes sense to put a diesel engine, if you do not chase the speed and walk in a season not less than 200 hours.
A planing boat over 36 feet long will also enjoy the diesel engine. Its weight and dimensions make it possible to take on board an economical heavyweight.
As everyone knows, a diesel engine costs much more than a petrol one. Maintenance, replacement parts, even the work of mechanics - all prices are much higher.
And in Russia, where the cost of diesel fuel was equal to the price of gasoline (and sometimes exceeds it, if compared with the 92nd), you must first calculate well that the savings were really «economical .
If the boat goes a lot and often, the diesel engine will take away its cost. For rare pleasure cruises, when the reel for a season does not exceed 200 hours, gasoline will be a more advantageous option even despite its good appetite.
The perpetual motion machine has not yet been invented. But if a diesel unit is not started and serviced on time, it will last twice as long as a similar petrol unit. Large and powerful marine engines are especially durable and reliable. Or at least modernized tractor - with thick-walled spare parts - which will take more than one thousand hours to wear out.
In pursuit of speed and in an effort to reduce weight, manufacturers reduce the thickness of diesel engine parts. And it is especially important that the block and cylinder heads are thick-walled. A huge amount of thermal energy released inside the cylinder heats the parts, and if the wall thickness is not enough, then due to the high stress deformation of the parts: crankshaft, bearings, pistons and cylinder walls change their geometric shape. They start to work improperly, with high overloads, and fail early. That's why converting automobile engines into marine engines is rarely successful. In any case, such engines serve on courts much less term, than on cars for which they have been designed.
A very important point is the absence of downtime in operation.
You should not assume that the small number of hours passed by the engine is an indicator of its large unused life.
As long as the boat remains motionless, the parts in the engine suffer corrosion, spoilage and deformation, which significantly reduces the life of the entire unit. Of course, there are cases when after years of downtime the engine has been started without a sneeze, but this is more the exception than the rule. A regularly running motor will last longer.
If we are talking about lightweight diesel engines convertible from automotive ones, their properties are very different from those of heavy tractor and ship engines. Highly accelerated, ideally suited for cars and roads, operating under constant load and with water resistance, without a gearbox, they do not withstand the task falling on them. The result is an overheated engine and a flushed oil film on the cylinder walls. The car engine has to be completely redesigned for new tasks, constant load, and not everybody does it or can do it. The automobile segment is widely moving in the XXI century, while the boat direction is only gaining momentum.
It is important to understand where you will operate your boat.
Why do Europeans love diesel engines so much? Because they take these engines for a long time, treat them with all the attention and care they deserve and maintain them in a specialized service that they have at every village. Their diesel is always of high quality and much cheaper than petrol. Therefore, the engine serves a long time, and the difference in price for fuel and economical consumption have time to pay off the high cost of the engine itself.
Doubt the choice of engine for displacement boat has to be in those regions where it is difficult to buy a diesel (such as in Venice) or where it is too cold. In the Baltic States, for example, walk to the last, and in the frost, as you know, diesel is much harder to start.
In Russia, if you walk only within the limits of your yacht club and the neighboring coasts, the question is usually solved with refueling. Even if you have canisters, there is still someone to drive from and where to go. But then it is immediately clear that your route is not far and the recoil at the end of the season is clearly no reason to brag. In this case, your choice is gasoline.
But for fans of the route, travelers in search of adventure and avid fishermen, occasionally seeking to find out where the fuel tank bottom, diesel can be a more reliable companion. Walking in maritime areas like Sochi, where gasoline in the water is not freely available at all, it is also better to choose diesel.
Besides refuelling, it is at tractor drivers and never refusing barges. You can pour it directly from the board. In addition, diesel is less explosive, so it is not a crime to smoke on board near the canister. The main thing is to remember that if you use plastic canisters, then let them be specialized canisters for oil products. Otherwise, the plastic dissolved in diesel will send your engine to the nearest service for a long rest.
As a diesel is good for fans of frequent nights on water, in which the generator is especially actively used. Exhaust gas of the gasoline engine is carbon monoxide gas and there is not enough pleasant in it. Diesel waste contains a small percentage of CO and is not dangerous for health. Although the presence of sulfur dioxide in them can cause slight headaches, even if there are no consequences.
Gasoline, as you know, can be found in the Russian expanses is very diverse: sometimes it is similar in quality to tea, brewed into three cups with one bag.
For the engine, no joy gasoline of this quality will not bring, make it and rest and increase, and the speed will take away. But it will work. So you can get to a good speaker on your own. At the very most, you'll have to blow out the candles and drain the water. That's not very good, but not as critical as a diesel.
Diesel mixed with water will silence the engine, and you - a lot of stress on the way to the workshop, where you will have to carry out overhaul of fuel equipment.
To avoid unpleasant moments, ideally it is necessary to get a separator, the filter with a settling tank and the sensor on water. And in very serious cases, when a tractor or a motor ship came out and something murky and unclear color is splashing in the container, it is better to let the fuel stand for at least a few hours: the top layer - in the tank, what is left - poured. «It is also» possible to stand up on an easy move, the decomposition process is faster due to vibration.
No gasoline engine will be happy if you need to carry a large heavy load: because of the hard work it will produce a lot of thermal energy, which will quickly lead to deformation of parts, and therefore to rapid wear of the engine itself. Diesel, in turn, does not like maximum speeds: working at the limit, parts are subjected to high loads, and thus, much faster failure.
Ideally, any engine should run at 80% of its capacity, that is, accelerate the boat to cruising speed, no more.
High speed engines live less. That's a fact you can't get away from. If a gasoline representative passes 900 motor hours before overhaul, the diesel can count on 1500 hours, or even more. Diesel, it is ship or converted tractor, and not converted from cars, have a motor resource and reliability incomparable to any modern gasoline. But they can be different as well. At almost eternal diesel engines the relation of a litrage to capacity aspires to value 1:2. That is the engine in volume of 650 cubic inches will serve infinitely long at capacity in 370 h.p., but will quickly «die» with capacity in 600 h.p. We will receive the strongly forced engine with short service life during which it besides will often ask for a date with the expensive mechanic.
But you should not rely only on the number of hours you have passed. If the engine with «infinite» resource will be idle and very occasionally (less than once a week) walk along the shore, it will not roll a lot of hours, but the corrosion during downtime will spoil the life of the internal components of the engine and will lead to wear of all systems much earlier than the due date. Therefore, a diesel tractor must be driven like a horse - all the time, so there was no stagnation. And, of course, in time to serve, and idle without movement - first of all. Then it will serve long and will not fail in the most necessary moment.
The main thing is to define the task that you set for your boat. And select the engine, taking into account all the nuances of size, weight, goals and expectations. For large and heavy displacement boats, rolling for a season of at least 250 hours, the diesel will be a good choice and will justify the hopes placed on it. For speed and lightness, for infrequent trips on a gliding boat, a gasoline engine will be the right and profitable solution. But whatever you choose, the most important factor in the end is your attitude. Timely MRO, quality service, care and attention - and your engine will walk long and like a watch.