Arnot

I may be wrong here but I had the freewheeling pulley fail on my sprinter van and what I first noticed was a lot of vibration at low engine speeds. What I think was happening was that there was a mechanical resonance in the belt and a mechanical resonance in the alternator torque requirement and the two were beating against each other. It didn't stop charging but the engine did idle roughly and seemed harsh whilst pulling off. Replacing the alternator (which had done nearly 200,000 miles and was past it's best) immediately resolved the problem. So; my take is that as well as the possible flywheel effect, with larger alternators the freewheeling pulleys may be necessary to prevent belt/alternator resonance at specific speeds. Possibly the ECU controlled alternators that shut down at lower speeds do a similar thing. Regards Arnot

Hi Snib, Been away in Geneva myself for a day or two, nice break... FWIW I suspect that Charles's starter is an Iskra Bosch ripoff but they are generally well made. I suggested he just leave it a while to let the newness wear off to see what happens but I suspect he prefers a black and white world with instant answers. Anyway Charles, listen to Snib! The washers will cause more problems long term than they cure short term, the starting torque will almost certainly loosen them in a matter of weeks and then there will be a poor earth to the starter (unless in the unlikely event it has a dedicated earth to the comm end bracket)the washers will turn into sparklers and the smoke will generally escape from places it was never intended to be. This process will precipitate a VERY large bill unless you are lucky. I can laser cut a 1mm spacer but honestly think that a little patience will prove it unecessary Regards Arnot

Actually in practice although the advantages hold, the disadvantages you percieve are not bourne out in reality in my experience. It sounds like the OP has a Beta 43 As it happens I carried out a 2v cell installation for a couple who use their boat similarly and because of the low impedance of the cells, the high output of the alterantor could be maintained for longer and replenish the battery quite quickly up to 85% ish. What they have experienced is that during the two or three hours cruising they do most days they can more than top the battery up to a level whereby if they do want to moor up for a day or two they then don't need to run their engine for battery charging. This has resulted in a drop of about 40% in fuel usage according to the records they keep. Obviously any battery left discharged for long periods will sulphate but again the pracitcal experience is that this is less servere than with leisure batteries. The cells I used were a custom 600Ah low profile traction cell which seem to fit into the swim location used in many boats and tend to suffer less from stratification. I think I am persuaded but in 20 years we should know for sure... Regards Arnot

Sorry, I just re-read this and it seems unduly harsh, it was a sensible question and a condescending answer. You deserved better! Sorry again, Arnot

Well; because this generator is enclosed in a sound insulated cabinet and a side effect of this is that it will be thermally insulated as well. So, if as I suspect from your outline of the symptoms and in addition, the history of raw water pump impeller problems, what you have is a cooling problem, if you bypass or disable the automatic stop it will merely continue to run. As it runs, it will get hotter, as it gets hotter the oil will start to break down and the sliding clearances in the engine will tighten up. Because of this, it will get hotter quicker and so on ad (not quite) infinitum. Eventually the oil will thin so much that the pressure will drop and the clearances will tighten up so far that it will seize up and come to an abrupt halt. At this stage, the cylinder head will be almost glowing and the paint will burn off it along with any loose oil around the engine. Because the engine has stopped, there won't be any sort of air flow or circulation in the cabinet, the built up heat will rise to the top of the cabinet and the insulation will start to heat up. If you are lucky at this stage it will merely smoke you out of the boat, if you are not so lucky it will catch fire. Once the insulation catches fire two things are likely to happen. The first is that it will issue clouds of poisonous gas from the smouldering foam insulation and the second is that the already hot oil in the bottom of the engine will be smoking enough to catch fire as well. How does that appeal? Alternatively you could adopt the engineering approach, find out what the problem with the cooling circuit is and fix it. However, it is entirely your choice.... Sweet dreams Arnot edit - another saucer of milk please?

If you insist, then quite possibly but I do need the generator type to go any further. FWIW my guess on the lifespan of the converted item would be about 1 hour! Then use of fire extinguisher and new engine required. Arnot

I think that when it comes to working on boats, as well as the self appointed experts and autodidacts there are both craftsmen and engineers. Inevitably both have (and have to have) an understanding of the others role and often there is significant overlap. For my part I always treat information offered with vigilance, I try to understand why it is being offered and take it that context. Could it be that that the person genuinely wants to impart factual knowledge that they know will help me? Could it be that the person wants to help me actually understand a problem so that I can sort it out myself? Could it be that the person is conscious of deficiencies in their own knowledge and are being bombastic to paper over their own perceived or real shortcomings, both to me and to themselves? Could it be that they can see me heading towards an outcome that they don’t want me to arrive at, for benign, malign or purely commercial reasons? Could it be that the person is intent on a mission of self aggrandisement? It is fair to say however that in general, people who use their eyes, ears and mouth in the proportion they are naturally endowed with are preferable to those who adopt the converse. Regards Arnot

M35? Nice one, I did just the same, still do occasionally. A good source of usable batteries to give to nice people who need them but can't afford them. Arnot

Without knowing for sure, I strongly suspect that this generator is raw water cooled and in my experience, this could well be the problem. If there is an obstruction in the raw water circuit or a problem with the pump or filters this will lead to shutdown at about the interval you are getting. One way of finding out if this may be the problem is to let the generator cut out and then restart after a few minutes, if it then stops again in a much shorter time it will probably be a coolant thing. As you have gathered it seems, the safety cut outs are there for a reason and have probebly already saved you a very expensive repair. Perhaps if you post what generator it is, there may be more help available. Regards Arnot

Hi Col, Good point about the belts but there are now two belts and they are the later orangey plasticy type. I didn't notice but hopefully Dan will check the rotation out. Thanks for the info by the way, I didn't realise that these belts were directional but now you mention it, it does make perfect sense. My preferred method with these is to cut the buggers off with a sharp knife and consign them to the nearest bin. Regards Arnot

I fixed it! Not a classic wiring job but then on a steamer there isn't the same level of vibration to worry about. It turned out that there was a tri-diode and this makes the field polarity conscious when used with the Butec regulator. Swapping the wires solved the first part of the problem. Then it didn't start immediately and I suspect that this was due to the reversed residual magnetism of the rotor due to the swapped wires but just might be a portent of problems to come such as brushes. However the Ellesmere gathering wasn't the time or place to start stripping it down. The next part was the drive belts (there are now two of them). Those segmented belts really are not suitable for any decent sized alternator but tightening them up managed to get about 30A out of the system at moderate propellor speed so hopefully that batteries got some charge on the trip home. Regards Arnot

The alternator it an old Butec, they were built like a brick outhouse and had a good low speed ouput. There is no technical reason why reversing the field connections would do the alternator any damage but sometimes there was a tri-diode that would at least prevent it working the other way round. It's a long time since I worked on one of these but maybe if I saw it I would recall the detials. There is something in my distant memory telling me that the field might need flashed to get it working again. What are the symptoms? Regards Arnot

This is an interesting illustration of the problem you have in putting vintage engeines into a narrow boat other than by trial and error or duplication of an installation that seems to work. The graph only starts at 400rpm and the power curve starts at 850rpm. Who amongst us with a JP2 ever runs it at 850rpm? Looking at the graph, I suspect that it was originally created for the use of a generator manufacturer who would be interested in the performance at 1000 and possibly 1200rpm along with the fuel consupmtion at these speeds. Also, the propeller power absorbtion seems to include some correction for transmission losses, not in itself unhelpful as long as it is declared. As well as this it doesn't declare what size the propeller was or if any reduction gearing was in use. I have had a look at what information I have and it isn't really any better though. Regretably, true measured graphs of the outputs of engines like the ones used in narrow boats at the speeds actually used don't seem to be available unless anyone who has rebuilt one did some dyno tests I don't know about (but would love to). Regards Arnot

Bear in mind that the curves shown for this engine only go from 600 to 1200 rpm and whilst this is appropriate for sea going vessels it doesn’t really apply to narrow boats. Also I suspect the graphs were prepared by the marketing department rather than the engineers. A true measured curve(?) would never be that straight. In summary, the information in this graph is a bit misleading. Persackerly (more or less)! It is the intersection of these curves that limits the engine speed and this is varied slightly by the extra load applied by a large alternator when fitted. But - once again, the engine power will never rise in a straight line in practice. It is easier however to look at the torque curves, cube law curves don't tend to be so revealing and at the end of the day, it's torque that keeps the prop turning in the real world. The reason it stays roughly flat is that from about 1/2 to 2/3 full revs depending on the characteristics of the engine, the torque falls as the speed rises and as power = revs x torque, the power curve flattens out. This was the basis of my suggestion of overpropping to try to more closely match the prop torque demand curve to the lower parts of the engine torque output curve whilst stationary at the expense of being able to achieve full revs at low boat speeds. Of course as the boat speed increases, then the upper portion of the rev range would become available if required. I can (and will) post a few graphs as soon as I can knock them into a suitable format which give an idea but it really isn’t that simple. For example, any graph will assume that the water being moved by the prop is stationary with respect to the water (bollard pull) but of course the actual speed will be the referenced to the boat speed. So, a prop trying to develop 4mph due to it’s pitch and speed whilst stationary will absorb a fair bit of torque but when the boat is already doing 4mph it will be almost zero. You then move on to the issue of what power is required to move your hull at a given speed and this is a whole new can of worms. There is much written on the topic but most assumes infinite clear water around and under the hull and anyone who has driven a narrow boat knows full well that this never happens and that the witdth and depth of the canal have a major impact on this. Finally, I am still working on a graph to predict the torque required to dismantle a tesco trolley with differing sizes of prop :-) It really is a fascinating conundrum isn't it? Regards Arnot

Actually it probably will deliver almost full power, just not full revs. I had a look at the curves on the Kelvin link and suspect that they have been finessed slightly to smooth them out, my experience of older long stroke diesels is that they have a power curve that rises towards half revs and then stays more or less constant from then on. Anyway, let us know how you get on.... Regards Arnot

Wotever... Nor is brain surgery. Isn't natural selection a marvellous thing? Seriously though, it's not that it is difficult, it's just that if you do get it wrong you die! If you don't understand it, the chances of the latter increase. Regards Arnot

Ditto! Arnot

As Tim points out, the problem is that the power curves don't fit and when you start to look at the torque curves it is blindingly obvious that without variable ratio drive it is just impossible to match a vintage long stroke diesel to a propeller on a slow boat. I think that Mykaskin was on the right track in thinking that torque was best used for matching props to engines but it's not as simple as the figures, you need to match the curve profiles within reason as well. To generalise, the output power curve of old diesels is pretty much flat for the top third to half of their rev range. This means that as the revs fall from maximum the torque rises to keep the power constant. It continues to do this as the revs fall until a certain point and then it falls too. This translates to a torque curve that has a massive hump in it at about half to two thirds of maximum revs and then falls away towards the maximum. Now to be quite specific, the torque demand curve of a propeller rises with the square of the speed more or less so as the speed doubles, the torque required quadruples and therefore the power required rises eightfold and the engine can't keep up! So in summary, it isn't possible to match a propeller to a vintage diesel with a fixed ratio transmission, you can more or less do it up to half engine max revs but after that there is no chance. Variable drive like hydrostatic does allow the engine output to be matched to the propeller requirement but it is very expensive to do and needs a bit of understanding to control. The good news is that it saves loads on fuel costs. In the same vein, the torque requirement of an alternator, especially the larger low cut in speed versions rises dramatically as they start to generate power and this sudden increase in demand can be more than the engine can supply at lower speeds at the same time as driving the prop. Interestingly when this is a problem, if you turn the alternator off as the engine builds up speed and then on again when it is near full speed, becuase the torque requirement comes down it will work just fine. To end on a practical note, my suggestion on the kelvin would be to massively overprop it and accept that only the first half of the rev range could be used. This would give good fuel economy, keep the engine sounding like it should and allow slow speed cruising and brake bite. As a pure gut feeling guess, how about a 24 square? Can anyone tell me if it is possible to post PDF's to the forum and if so I will post some graphs showing the above issues. Regards Arnot

You might do better to look at the Mastervolt or Victron combi units. As far as I can see, the Vetus kit is not made by them just rebadged. The benefit of a combi is that it includes all the automatic changeover switchgear for the mains side so it is far simpler to install. You may need a bit of reprogramming to charge the batteries from a generator using a combi though, they can be fussy about mains quality. Regards Arnot

Have a look at these. You will need to look under worklamps. I used one of the 130mm round units on a trip from London a couple of years ago and it was fine for tunnels but could have been brighter for night cruising. Regards Arnot

But you can get a tractor regulator for them... This helps a bit.

It might be that there is something still connected to the downside of the RCD, this often skews the test results. Popular candidates are anything with a switch mode supply, I often have problems with installations with the Sterling battery chargers they seem to send my fluke RCD tester doolally! Arnot

There will be a voltage showing between live and earth and a similar voltage between neutral and earth for one of two reasons. The first is it your inverter is of the "two phase" type where the protective earth is connected to the centre point between the two phase outputs in the same way that some generators are wired and all 110V transformers are. If this is the case you cannot bond the neutral to eath but inverters of this configuration are very rare and were probably imported illegally. The more likely explanation is that the output of the inverter is galvanically isolated from the casing. This implies no connection but it is not quite the case; mainly for the purposes of radio interference suppression, there is a small capacitor connected between each of the outputs and the earth to ensure that it remains somewhere between the two dependant on the accuracy and condition of them. In this case, a bulb connected between either output and earth will not light and whilst connected the voltage between the other output and earth will rise to more or less the same as the full output. If your inverter is one of these, as Gibbo said, you can safely fit a neutral to earth bond. There is some (understandable) confusion about what "live" and "neutral" mean. Essentialy when any AC power is transferred through a transformer, the output becomes isolated from the input, sometimes such as in the case of power tool transformers and isolation transformers this is a benefit, in other cases such as with power inverters (that contain a transformer) and your domestic mains supply this can compromise safety. The way round this is to connect one of the AC output wires to the protective earth. In a mains supply this is done at the supplying sub-station and/or as the supply enters the property. In an inverter or a generator this is usually done at the output connector either by the manufacturer or by the installer. It is this connection (bonding) is the only thing that distinguishes the neutral from the live wires. Correctly speaking, an inverter with no earth bond to the output doesn't actually have a neutral, it has two lives but each at about half the full output voltage. An inverter with a centre tap or a power tool transformer also has what amount to two lives. It probably won't but I hope this cools your fevered brain! Regards Arnot

There is are some other factors in this that you may want to consider... Inverters lose efficiency as their supply voltge falls, this has two symptoms. The obvious problem is that you will be wasting diesel but the not so obvious problem is that the larger thermal cycling will tend to reduce the lifespan of the inverter. The losses in cables increase exponentially as the current in them rises, this is why the national grid runs at 330Kv and at the other end of the spectrum larger narrow boat installations tend to be 24V. Doubling the cables will half the cable losses. Taken together, doubling the cable would probably reduce the losses by 75% and prolong the life of the installation. IMHO the cost of the extra cable would be well worthwhile and taken in the contect of the cost of the inverter, not actually a large amount. Of course, you could just consider your inverter as a rather expensive part of your heating system :-) Regards Arnot

It would help to know what make and model the inverter is but... The low voltage may be either a symptom of your meter measuring a non sine waveform or it could be that the voltage is reduced at low power outputs to save power when it is on standby, some do this. I guess that as long s it is running what you want it to run without problems there is no point in doing anything about it. Regarding the assymetric voltges on live and neutral, It sounds as though your inverter is one where the neutral is not bonded to the protective earth. On most units this can be achieved by simply wiring a link between the neutral and earth at the inverter but you will need to make sure that this is possible with your unit. You can do this by temporarily connecting an incadescent bulb between both live and neutral and protective earth, it should not light up and when connected the voltage between the other line and earth should be more or less the same as the live to neutral voltage. Also it is essential to have RCD protection as close the the inverter as possible and a good bond to the hull of the boat (given it is a metal hull of course). Don't worry about the lack of a ring main, as long as your boat is wired with 2.5mm blue artic (as most are), it will carry even the full output of the inverter with negligible volt drop. Regards Arnot