|Coconut Hart Surgery|
Changing an engine is the equivalent of open hart surgery
for a boat. It is the steady beat of the diesel engine that brings you in
and out of port as well as rescue you when it is blowing too much
or too little. The steady thump of a reliable engine provides a great sense
of security as well as fill up your batteries and power other systems you
might have onboard. Our engine is getting old and has been giving us a few
headaches. The end result is that we have stopped trusting it and instead
are constantly listening out for something wrong. For a relaxed family
cruising lifestyle this is not a good situation to be in. So we decided to
blow our budget completely and invest in a new Yanmar. Even though our Volvo
is running nicely at the moment it is also a fact that it is 20 years old
and spare parts are getting scarce. Something mechanics all through Europe
has been reminding us of. This situation does not get any better as you
venture further a field.
After having made the decision to re-power we had to decide on what type of installation. I'll share some of those thoughts with you here, so this page is for the more technically interested yachties!
Deciding to re-power your yacht is a major decision as it has implications for other systems in your yacht and of cause requires a heap of money. But done right it will be an investment that will bring you many years of faithful service. We decided to go for a Yanmar. These engines have a great reputation among the cruising fraternity. Spare parts are available all over the world and they are very reliable. There are other makes as well and the difference between them might not be so large but choosing a power-plant for your boat you would have to consider the following;
1. Most diesel engines today are very reliable. As long as they get clean fuel, have their oil changed, get enough clean air and cooling ,they should provide years of faithful service. The servicing you have to do is not much really, but absolutely vital. It is not uncommon to end up with dirty fuel and if the contaminants make it all the way into the engine, notably the diesel pump, repairs can become very costly. It therefore important to install a good diesel filter/water separator in ADDITION to what is delivered with the engine. Racor make the best known filters. Make sure that you install it so that you can get to it easily and see it clearly so as to make visual inspection easy. Thinking through how your engine will be installed in the engine room will help you make up your mind on what engine to choose, and/or what changes needs to be made. You can e.g get external oil filters that you can place more conveniently for servicing.
One factor to consider is engine revs. Higher revs means a smaller lighter engine for the same output. But higher revs also means more wear and tear, shorter servicing intervals and a more fragile engine. On a sailing boat weight should not be a consideration. If the engine in a, lets say 40 foot 12 ton yacht, weights 350 or 250 kg does not matter much. Noise is also an issue as higher rev engines make a different and sometimes louder noise. We settled for a Yanmar which is rated 55HP at 3000 revs. This is today considered a medium rev engine. The Volvo we have today is rated 62 at 4500 revs! It is easy to convert this to wear and tear when you think of how many more rotations the high rev engine has to do for the same output. On the market today you will find engines with considerable lower revs than 3000. Most engines can even be downgraded to a lower rpm range. This is done by making adjustments to e.g. the diesel pump. The main engine stays the same.
Your engine will often have to do other jobs than powering your yacht through the water. Your batteries might have to be charged, the fridge or water-maker powered. Often the peripherals are the most critical for your engines reliability. Obviously if the component bolted to the engine are no good then it will create trouble and hassles. It is also true however that the installation itself can be influenced by the add-ons. Maybe the added weight and stress of pulleys and compressors will be too much. Is the engine prepared for it? Are the engine mounts sized for the extra weight and the shift in weight distribution?
Diesel engines like having work to do. Running it idle is one of the worst things you could do as it never get hot enough and the carbon build up can destroy the engine. It is therefore a good idea to make sure the engine works as hard as possible when e.g charging batteries by specifying the largest alternator and/or bolting on one extra (+100 amp for a mid size engine).
The engine will rest on flexible engine mounts that dampen the vibrations and transfer the power from the engine to the hull. This is a hard job and you rely on it. Imagine one engine mount breaking while powering in heavy seas! You need to choose the best engine mounts and make sure they are installed properly. A new engine might imply changes in the engine beds where the mounts are fixed. Don't save here. Get the job done properly.
Transferring the power from the engine to the propeller is the job of the coupling. There are roughly two types; flexible couplings and fixed couplings. The latter are cheaper and simpler. They also lasts longer. The flexible couplings swallows up vibration and are more lenient to misalignments. They do not last for ever however and you need to carry a spare.
2. Spare part availability is vital for the long distance cruiser. Too often we hear about crew having to spend weeks in the wrong locations waiting for parts. If you cruise in European waters this is not such a big issue. Going further a field it becomes critical. This would mean that you need to choose one of the well known brands. Many engines are based on the same basic diesels. This might be engines like Kubota that are used in many trucks and industrial applications as well as for marine use. Yanmar engines are found in many different applications world wide which was strong argument for choosing this engine for Coconut. The volume of their production is another strong argument. Someone said Yanmar produces more engines a week than Volvo does in a year. If that is true I do not know but with this type of distribution spare parts are likely to be found everywhere.
Do carry a good amount of the most common spares onboard. Depending on the age of your engine this might be e.g oil and fuel filters (lots!), fan belts and enough oil for at least one full change, injectors, an alternator and a starter motor. Consult with your engine supplier.
3. Maintaining your diesel is not difficult work, but it can be made difficult by a faulty installation or bad design. Major servicing points need to be easy to get at. If it is difficult to get to the impeller you might be less likely to check it. If the fuel filter is placed where you cant see it then how will you know what you are feeding your engine? Look for an engine where major servicing points (e.g. cooling water impeller, oil filter, dip stick, fuel filter, raw water strainer) are easy to get at and placed logically . A lot of thought has to go into placing all the auxillary systems. Where could the primary fuel filter be placed so that you can easily see it? Can you change filter without making a mess? How are you gonig to bring in fresh air to the engine room. Diesels are hungry for air and performance goes down if this is not provided. You also need to get rid of all that exess heat.
Going through the list above the Yanmar came out on top. The interesting thing is also to note that there is very little price difference between most brands. But you might be able to save quite a bit by shopping around and being flexible as to where your new engine is going to be fitted. We choose Waterline Yacht Services in Lanzarote. They where on the way, it's a beautiful location and they are well organised. It is also a help that the Canary islands enjoy a special economic status with lower taxes.
Getting that steel hart out of the boat can be a very complicated process where parts of the interior has to be dismantled even cut out to make it possible to lift the old engine out and get the new one in. Some even have to dismantle the engine and bring it onboard in parts! If you are in the market for a new (used) boat it will pay off to check this. Will the interior have to come out? Sooner or later you will have to do something with the engine that will require it removed from the boat.
Luckily Coconut is build the old fashioned way. Nearly everything can be unscrewed and removed. She also have a very large and easily accessible engine room. It occupies the full length of the cockpit. To get the engine out we simply unscrew the cockpit floor to expose a large hatch big enough for the engine to pass through without too much difficulty.
This site was last updated 18-11-2007 12:24:42