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nicknorman

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Posts posted by nicknorman

  1. 7 hours ago, blackrose said:

    I never really understood what the benefit of the Travelpower was over just switching on your inverter? I guess it means you're not drawing power from the batteries, but if your electrical system can't handle running a washing machine while the batteries are being charged by the alternator then it's not up to much.

     

    For us it was a marginal choice but I'm glad we went for it. It gives redundancy- we have 2 sources of mains power (TP or inverter) and 2 sources of battery charging (via alternator, or via TP and battery charging part of the Combi). And as I said, a heavy load can be shared by the TP, the alternator and the batteries so as to avoid stressing things too much at low engine rpm. These days with Li batteries we only tend to use it for the tumble drier, which is a 2kw load for perhaps 45 mins or more, much harsher than the washing machine heat cycle. With the latter we just run it from the inverter/batteries/alternator.

  2. ..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.

  3. 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.

  4. 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

     

     

     

     

    • Greenie 1
  5. 1 hour ago, Ronaldo47 said:

    If your installation  has RCD protection,  any difference above a threshold between the currents flowing L and N conductors, such as a leakage to Earth, ought to disconnect the supply,  so the type of fault current situation shown should not happen. 

     

    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.

  6. 30 minutes ago, jim mitchell said:

     -  a sort of its 'always done this way' regarding layout location of batteries. water / fuel tanks etc

     

     

    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.

    • Greenie 4
  7. 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.

  8. 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.

    • Greenie 1
  9. 1 hour ago, Jon57 said:

    With more people going down the lithium battery route. 240 volt fridge and freezers will be a no brainier. 

    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.

  10. 8 minutes ago, Steve Manc said:

    Ian

     

    Re number of people on boat re insurance.

    I am not aware there's a clause on maximum number of people on the narrowboat. Can you please expand?

    Thanks 

    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.

  11. 3 minutes ago, Steve Manc said:

    All

     

    Thanks for your replies.

     

    I have secured one from Midland Chandlers.

     

    The inside of the fridge only achieving 12 degs and frozen not fully frozen. Spoke with shoreline last year who said may need gas. Sadly ours is an old type of gas. Fridge is over 10 years old. Time to move on 

     

    Also need 12 volts

     

    Again thanks for your replies 

     

    https://www.shoreline-marine.co.uk/product-category/type/narrow-boats/?_type=narrow-boats&_width=355.00%2C712.50&_height=500.00%2C1790.00

    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.

  12. 22 hours ago, MtB said:

     

    I'm sure the cells wouldn't know or care.

     

    Paralleling the three BMSs might have negative consequences though. Two together might recognise they've been paralleled and talk to each other, but a crowd of three might not be so polite.

     

     

     

    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.

    • Greenie 1
  13. 39 minutes ago, IanD said:

     

    They did, but I believe they more recently said they won't allow this any more -- presumably they're worried about the increased risk of a weighed-down boat sinking in the tunnel due to things like air intakes being too close to the waterline.

     

    I haven't got anywhere to add much more weight in the bows anyway, there's already a load of steel in the bottom of the bow locker plus 8 56lb weights on top of it (and the anchor and chain)...

    What you need to do is get rid of that lithium rubbish and put in plenty of lead acid. That would sort it!

    • Haha 1
  14. 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?

  15. 2 hours ago, mrsmelly said:

    I had a First, today. Bought a motorhome for a laugh and removed leisure battery. I have had dozens of batteries over the years and on the boats I used to Skipper we had about 2 dozen in service batteries at any one time on the two boats. I have measured duff ones that have stood about for a couple of years but todays reading of 0.00 is an absolute first lol. Looks fairly newish, hilarious, new battery ordered this afternoon. Just sayin like.

     

    According to the manfacturer it is not knackered, it is just resting or maybe a bit stunned.

    • Haha 4
  16. 1 hour ago, Stroudwater1 said:

    Thanks Nick, is it not possible to circulate water around something hot on the engine, say the exhaust to heat up though? Perhaps that’s more complicated than an immersion? 

    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

  17. 8 minutes ago, Stroudwater1 said:

    Going right back to the initial question I’m easily confused but cant an SR2 heat water without the need for an immersion heater, if so is it as good an option as an immersion? 
     

    “I've an old Lister SR2 so a calorifier heated by the engine isn't an option.”

    It’s an air cooled engine, there is no engine coolant to circulate through a calorifier.

  18. 1 hour ago, MtB said:

     

    I fear you may misunderstand. The boiling point of water varies with pressure. So if you pressurise it (e.g. a 2 or 3 bar inside a calorifier), it will boil at a higher temperature than 100c. If you then allow the pressure to drop, even a little bit, the whole volume of water will turn to steam in one go. 

     

    Or maybe you've grasped this risk all along, as I know you are a clever bloke. 

    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.

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