dmr

I think a few people have managed to bridge hop on the Bristol Avon (Bristol to Bath) but its not for the feint hearted or inexperienced. The number of sunk boats on that stretch is a reminder of just how dangerous that river can be. Transport into Bristol not that easy either. There is potential for some serious bridge hopping in Birmingham and a fair few are doing it, in fact there there is so much canal that its not even bridge hopping. An easy day gets you into pleasant countryside on the North Stratford. ..............Dave

A few thoughts... 55 amps is plenty for two Trojans. BUT You would be better with 4 or even 6 Trojans, would be nice if you only needed to run the engine every other day, or even every third day. Don't worry if you need to take the Trojans a bit below 50% charge to achieve this. A Smartgage and some sort of current monitor is almost essential. Charging the Trojans at 14.8 volt (or even a bit more) is Essential. A means of equalising at 15.5 volts once in a while is almost essential. 55 amps would be just ok for 4 Trojans, but not so good for 6. You could increase charge current a bit if you can combine the output from the starter alternator (if you have one). With 4 or 6 Trojans a bigger alternator will certainly reduce charge time (engine running) but probably not by quite as much as you hope. If you do fit a bigger alternator then your decision to fit a larger framed model is a good one. Make your own decision about using a generator, advice from the forum is not always good on this subject. Solar panels will help but you will need a lot to avoid engine running in winter, and lots and lots if you want to wash in hot water!!! you should find the alternator polyV pulley on eBay. If the crank pulley is a taper lock then engineering suppliers on the www will sell you one. If it bolts to the crank then it will be harder to find. Betas higher prices will reflect the time they have spent in sourcing these components. ..........Dave

If its a leisure boat then keep the lovely old stove, if its a liveaboard then sadly a modern welded steel stove would be a much better option. Have you got room for both?? .............Dave

another thought, you could probably get away with he existing bracket. Get a length of studding (stainless?) right through the two holes in the bracket and locate the rear (overhung) alternator foot with a pair of nuts, its a bit punk but we are only talking an inch of overhang. Rather nicer would be to get a proper threaded spacer made up, would not cost much. ............Dave

Neil is indeed a good bloke but I believe he only specialises in the JD3. Have a look at the Beta website to find who does the Kubota based engines. .........Dave Are you a full time off grid liveaboard or a leisure boater???? This may influence the choice of alternator. ............Dave

You are leaving this a bit late, if you have any delays then you may well start to hit the stoppages. Abingdon closes on the 3rd November? As the year goes on there is an increased risk of the Thames going on to yellow or red boards. In view of possible increased flows, and if you are not experienced at Rivers, then I would go up the Thames. Going up is easier and safer (though several forum members would probably say the opposite). if it rains hard then going down through Osney is always the first thing to become difficult. Also going up the Thames avoids the slightly tricky turn into Brentford. ............Dave

I believe Unity now has a diesel engine. The only big traffic jam I have ever seen on the K&A was the one following Unity. Also she could not get up through Newbury with any significant flow on the Kennet, She was substantially solar powered so that didn't help. .............Dave

I have seen something like this before. I think the owner said it was an ex hire boat and the engine was at the front to make it much quieter for the crew on the back. This would explain the odd combination of a forward engine and cruiser stern. There are better ways of making an engine quiet. ...........Dave

I suspect that all sorts of grand names like "marine" and "high output" are applied to alternators. Certainly some perform better than others, but I am coming to the opinion that although some (though not all) can deliver their rated output for a short burst very few are able to do this for several hours everyday as a liveaboard may require, rather like wot Spuds said really. This is partly because In narrow boats we usually struggle to get the alternator running fast enough so often just manage to get it producing almost maximum current but without the extra cooling that a higher speed would give. ..............Dave

This is very true. I do almost everything myself so the sudden big bills come in lumps of £500 rather than £1000, but then some years we get two of them. And if its a major engine failure its much more than £1000. ...........Dave

Read and follow the instructions when doing self service on Thames locks. Random and impatient button pressing can put the system into a shut down that only the lock keeper (who has gone home the night) can reset. How do I know this?????? And if you go down to Brentford on a spring tide there can be a very significant flow at Brentford. We were delivering a very under powered boat for a friend and given expert advice to cut the corner! ..........Dave

No sign of a trip boat, We are travelling with friends so used all of the mooring pontoon between us, plus another boat moored alongside us. Left about 11am (Monday) . However a small crowd had gathered in the picnic area so not sure if it was a just picnic or if a trip boat was expected later. Dave

Its got very little flow now but some of those bends and offset bridges are still tricky for our 71 foot, certainly would not want to be going downstream with any significant flow. ..........Dave Yes, I was perhaps too positive about this River, the beer is not too good and the locals are indeed unfriendly: a few wrong ideas and the buggers cut your head off. Nice steam railway though the trains are all foreign. ...........Dave

All of the Thames is wonderful, (or at least almost all of it), but we are currently exploring the Nene and that is even better. I am amazed that less people explore and rave about this river. ...........Dave

Hope to speak to Iskra tomoro, too busy cruising today! No scope to increase alternator speed, engine pulley as big as it can be and alternator pulley already smaller than it really should be. I suspect many boat alternators run at least favourable speed, just into the maximum current region without the extra cooling that higher speed gives. Its a "proper" engine room so ambient temperature is fine. I am beginning to think that small frame alternators are not designed for or able to deliver almost full output continuously. ..........Dave

Today the alternator started off producing about 82 amps and after a while this had dropped to about 77 amps. After hopefully letting the temperatures stabilise I tried to do some measurements with a thermocouple probe. These could be under-readings as they depend on getting a good contact with the thermocouple. Case 120 deg C Stator Core 145 Stator winding 170 Diode heatsink/mounting 90 ...........Dave

Just protecting myself from the forum pedants. Bearing heating is down to speed and belt tension rather than current. I've forgotten what little magnetic circuit theory I ever knew but I would think that this is current related too. So here goes.... Electrical losses (heating) are totally related to the current produced, the voltage has zero influence!!!! ...........Dave

The actual heating is almost totally due to the current, not the voltage. In fact a 24v alternator should run cooler than the 12v alternator of the same power. As Nick says this really is demonstrated by the TravelPower. Today my 100 amp Iskra was cooking itself producing about 800w but the TravelPower was making over 1000w and was barely warm. What does happen when the voltage is increased using an external regulator is that the alternator will spend a longer time (possibly a much longer time) running flat out so there is more time for the temperature to build up. .............Dave

I have always assumed it is the number of cycles to the specified DoD. From memory I think this is about 1500 for Trojans going to 50%. Also its "end of useful life" rather than death, end of life might be as good as 80% of original capacity for some batteries. ............Dave

You asked for comments so here goes I reckon its a 10mm (Z section) belt in a 13mm (A section) pulley. You can get away with this as long as the belt does not bottom out. Surprisingly a 13mm belt will also run ok in a 10mm pulley. As the 13mm belt is stronger and transmits more power I would go for a 13 here even if the alternator pulley is 10mm (not clear from the photo). If both pulleys are 13mm and the belt is 10mm then I reckon the alternator will actually spin marginally faster as long as the belt is not slipping. I am just upgrading my alternator system now and have realised that I have (had) a 13mm belt in a big (16mm) pulley and a 13mm belt in a 10mm pulley and its all done 12000 hours with no great problems! ............Dave

Trojans are specified to go right down to 20% SOC so don't worry. Despite popular but misguided opinion, going below 50% SOC does not damage batteries, it just shortens their life rather more than going to 50% will. The 50% rule is really a design guide for choosing the size of a battery bank. If going down to 40% means that you can go an extra day without running the engine, with resulting diesel saving, then this may well be more cost effective. ..........Dave

I think Beta are very negative/cautious about external regulators. A few years ago they produced there own unit which was a bit of a disaster and I suspect cost them dearly in warrantee claims. I always thought that an external regulator just increased to voltage during absorption so did not massively increase the stress on the alternator but this exercise has shown that in some cases the controller makes the alternator work much harder. I am surprised that the alternator is sold with a 14.2v regulator, I hope this was not done just to reduce the thermal stress. ............Dave

Don't have an IR thermometer in my toolbox. I do have thermocouple stuff but not sure how I would fix one to the alternator in a satisfactory way. I imagine the IR themometer will be seeing the actual windings through the slots rather than just the case temperature, The eBay,story, that I have reasons to believe, is that after just 500 hours the owner felt he needed more output so fitted the 175 amp unit. I suspect the poor performance was mostly down to the 14.2 volt regulator. ............Dave

No its quite a small thing really. Looking at the Iskra "data sheets" it appears that there is also a 120amp version so I reckon there is some safety margin on the 100amp unit. It also says that it copes with an ambient temperature of up to 100 degreeC which I find hard to believe.s

I reckon 0.3v drop at 175 amps is actually quite impressive, we have a lot more, I assume that 0.3 includes the isolator and a current shunt?. The internal regulator does appear fairly soft, I suspect the Adverc is a bit tighter. Without the Adverc and with the internal regulator at 14.2v I did not really see any bulk charging, the regulator was starting to do its stuff within a couple of minutes of starting the engine. This is really one of the sources of my concern as I charge at 14.8v or even 15v in winter so will work this alternator much harder than if it was left at 14.2v. It stinks of hot paint! but then if the previous owner did not have an Adverc or similar then the alternator has probably never been up to temperature before. Assuming you have an Adverc/Sterling external regulator then the definitive test would be to short it out to give full field excitation and see if the alternator output current increases. Dunno about you but I'm not brave enough to do that! ..........Dave If you have nothing else turned on then that full 175 amps will go into the Trojans which is well above what is generally recommended. Trojan say 10 to 13%, most "experts" say 25% whilst you will be doing almost 40%. However I am starting to think Trojans are pretty indestructible (as I quickly touch some scumble!) ..........Dave