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nicknorman

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Everything posted by nicknorman

  1. ..although you could just avoid doing the hoovering while the washing machine is on heat cycle! In order to actually get 3.5kVA (or 5kVA) you have to run the engine quite fast. Well above idle anyway. This causes a problem when cruising if you are minded to slow down past moored boats. I’ve set ours up now so that when cruising eg with the tumble drier on, the Combi limits the travelpower drain to 1kw and the rest comes from the alternator (limited to about 1kw, (or about 750w at idle) and anything else from the batteries. So it can tolerate idle without belt slip.
  2. It’s nothing to do with Whispergen. Nor is it owned by Barrus. It is a company formed by a chap who worked for Victron and left to form Mastervolt and now Whisperpower. They make a lot of stuff, including a “Travelpower” lookalike. If the Dometic Travelpower is no longer available, I guess this is a good alternative. Personally I think 5kVA is a lot for your average canalboat engine to run, maybe they do a smaller one? Would be interesting to know the price.
  3. We are talking about 12v LEDs so the whole dimmable or non-dimmable thing is not relevant. The best (and probably only) way to dim a variety of LED lighting - those with resistive current limiting (rated at 12v only) or those with SMPS current limiting (rated at eg 9-30v) is to use PWM (aka pulse width modulation). Our DC distribution system includes built in PWM dimming for lighting circuits and it is effective both on LEDs with resistive and LEDs with SMPS current limiting. I did wonder if it would work with the latter but it does, I guess because the PWM frequency is around 200Hz whereas the SMPS frequency is more like 200KHz. I guess something like this would do, provided you don’t have more than 2A of current drain for the lighting circuit. https://www.ebay.co.uk/itm/155839260100 Or this one if you want a nice bezel and knob https://www.ebay.co.uk/itm/404344402086
  4. Yes a filter is designed to collect gunge and therefore will inevitably block. A whale gulper doesn’t need a filter, it can pass the usual hair and soap without a problem. Just replace everything with a whale gulper.
  5. Yes normally cable sizing for a 12v system is based on voltage drop rather than heating. There is a handy calculator here - scroll down to find it: https://www.12voltplanet.co.uk/cable-sizing-selection.html
  6. The RCD protection is usually 30mA which is a current that could be on the borderline of being fatal. A more sensitive RCD (lower current to trip) will likely suffer from nuisance trips, a less sensitive one could be fatal before it trips. BUT this is all assuming a scenario where someone touches a live thing. Ouch! You pull your hand away by reflex. But a water borne shock is different. If we consider the case where the hull has connected to live, you have a moderate current (depending on the conductivity of the water which varies a lot with impurity levels), maybe a few amps. Not enough to trip a 16A breaker. The hull is at 230v, the bank a few feet away is at 0v, so there is a strong electric field (voltage gradient) in the water. Now insert a human body in the water, not touching either the bank or the boat (they fell in). One part of the body is closer to the boat, another part of the body is closer to the bank. So there is a voltage gradient across the body. It might give more than 30mA through the body which could be fatal. But even if it is only 20mA, you can’t go “Ouch!” and pull your hand away, you are stuck in the water being electrocuted. And that 20mA, whilst not fatal in itself, causes muscular spasm and paralysis, so the shock doesn’t kill you but the drowning does.
  7. There is definitely a sort of "always done this way" thing. However that is not necessarily a bad thing. With canal boats, sometimes things are "always done this way" because several hundred years of experience says this is the best way. Someone new to canal boats sometimes comes along and says "but I want to do it differently, this way". And they do. And then they realise why it was always done a certain way. The canal infrastructure - locks, bridges etc) has a big bearing on the shape of boats and fighting that is never going to be a good look. I am not a backwards looking person, I like innovation and new stuff - when it is an improvement. But sometimes sticking with the tried and tested ways of doing stuff turns out to be the best idea.
  8. Then there is the consideration that it’s good to have one end of the boat shallow-drafted so that you can eg poke it into a silted-up winding point to turn the boat round. Leisure boats tend to have the heavy engine at the back and the back has to be well submerged to keep the propellor well below the surface. If you wanted to ballast the bow down to the same extent, you would have to add a lot of ballast and this would overall make the boat very heavy. Then there is the issue of the bilges under the cabin. Condensation, window and plumbing leaks can result in water getting into the cabin bilge. It is good if this all runs to one end where it can be detected and pumped/sponged out. But overall, with a squat differential between the front and rear of a couple of inches over 57’ or so, the change in attitude is not noticeable.
  9. Other types of wood are available. Our boat was lined with maple veneered ply. Makes it very light and airy and maple is quite a hard wood, resists scratches etc. Not much grain though, but we wanted a fairly “clean” look.
  10. We do leave the inverter on 24/7 when on the boat, but when it came to the possibility of replacing the fridge, my concern about going for 240v was that the inverter was another layer of possible failure mode. There would be nothing worse than being stuck on the boat without any ice to put in my gin and tonic! On the plus side, our inverter is now 13 years old and never put a foot wrong On the minus side, our inverter is now 13 years old and so is probably due for a failure fairly soon! The other issue is that I wondered if there could be an overload caused by having the electric kettle etc on, then the fridge kicks in with its very high, if short lived, start up transient. The inverter is Mastervolt 12/2500-100 ie 2500VA but it does seem to be pretty fully taxed by a 2kw kettle. Although the spec does say 4000w overload for 5 secs which I guess should cover it.
  11. The Recreational Craft Directive and other such boat design rules require stability assessments. In order to guarantee stability, the case where everyone on board all go to one side of the boat has to be taken into account. In order to know how much effect this will have, there has to be a known (maximum) number of people on board. In the case of the RCD, the plaque will specify the maximum number of people on board. For our boat it is 8, IIIRC. If you exceed that, the certification of the boat is invalid and under those circumstances the insurance co. has a good get-out. For a narrowboat, you would stand eg 8 people on the gunnel at one side, and hope it doesn’t roll over.
  12. I noticed our 11 year old shoreline fridge was running the compressor a lot of the time, even in average weather. In hot weather it wasn’t cold enough. I suspected low gas. Yes it was an older type of gas but I managed to get a top up kit from ebay with a compatible gas, around £80 IIRC. This fixed the problem. Sorry, I realise it is too late for you.
  13. I think the thing with paralleling several Li batteries with built in BMS comes down to the limitations of the BMS and what happens if there is imbalance in current handling at high loads. If you need to take out 3C (C of each battery) in a triple paralleled setup, you hope that the current is evenly shared between the batteries. But differences in on resistance of the BMS MOSFETs, and their positive resitance vs temperature coefficient means that if you discharge close to the limits of the BMSs you risk a cascade failure - one BMS has slightly higher resistance which means it gets hotter which means the resistance increases which means it gets even hotter etc etc. But IMO if you never discharge (or charge) close to the BMS current limit, as is the case for narrowboats most of the time, I can't see it being a problem.
  14. What you need to do is get rid of that lithium rubbish and put in plenty of lead acid. That would sort it!
  15. My mate had 2 boats built in Rugby ( or Hillmorton anyway). One in around 1974, built by Colin Payne as a sailaway. It had a wooden top, 47’ trad stern with lister 3 pot air cooled engine. The other was I think fitted out in Rugby by Barry Smith (I think?) but the hull was Evans, completed around 1990. Maybe if the OP posted some photos of their boat, people might recognise the maker?
  16. According to the manfacturer it is not knackered, it is just resting or maybe a bit stunned.
  17. Not if they are lithium batteries, which they are.
  18. It would be possible but very ineffective because the amount of heat transferred from the exhaust to the outside of the exhaust pipe is not a lot. And if you extract heat from an exhaust system, the cooling hot gasses (which contain a lot of H2O) condense. Permanently having liquid water in the exhaust is not going to make for a long and happy life
  19. It’s an air cooled engine, there is no engine coolant to circulate through a calorifier.
  20. I don’t know, I was just repeating what you said. But my point was that with a release of pressure from eg a PRV, this wouldn’t happen.
  21. Well yes and no. Yes if you allow the pressure to drop, the whole volume will turn to steam. But this won’t happen eg if a PRV opens. Enough water will turn to steam to keep the pressure inside the calorifier constant. So yes eventually all the water will exit the PRV as steam, but what won’t happen is that all the water turns instantly to steam and increases the pressure in the calorifier such that eg it bursts. Well, unless the calorifier bursting is the first release of pressure. But then you have already passed the normal thermostat, the overtemp cutoff stat, and the PRV. Normally one doesn’t consider triple failures of triplexed protection systems.
  22. I would go for 1kw. Although the Li could cope with 2kw everything is a bit more stressed (battery cables, inverter etc) with prolonged operation at 2kw. And if you are lucky, on a sunny day the solar will provide most of it. You will have a problem in winter though, lots of engine running ie more than 3 x engine time for every 1 time at 1kw. Have you considered another source of hot water such as a diesel heater for the calorifier or an instant gas water heater? You could plumb the latter in with a changeover valve so you can use the instant gas heater in winter and switch to the calorifier powered by solar/batteries in summer.
  23. I think a normal domestic immersion heater only has a very small temperature coefficient (variation of resistance with temperature) so the nominal power rating of 1kw or 2kw is all you need to consider. I think you may have been looking at eg aquarium immersion heaters which have a large temperature coefficient in order to provide a degree of temperature regulation. There is a difference between a MS vs Screwfix heater element, the former is designed for boats with a calorifier heated by the engine. They have the "last resort" thermal trip set to a higher temperature so that it doesn't trip with engine coolant at close to boiling point. But in your case, with an air cooled engine, you might as well use the Screwfix one. We have 1kw, that is quite adequate when you are connected to shore power for long periods. Hot water rises to the top so you get some hot water pretty quickly, but if you want the whole tank hot then it does take a few hours. If you want to heat the water up quickly then maybe 2kw would be better, but if you are not on shore power then where is the electrical power going to come from. If from batteries/alternator/inverter, I suggest that 1kw is a better option.
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