wakey_wake

Yes, I'm capable of understanding and predicting this hazard but I had not done. ?

Hypothesis 1: first owner neglected it, second owner fixed it up with reasonable measures, third owner lost the history or isn't sharing? Hypothesis 2 (weaker because I don't know how surveyors do this): this 10% / 20% number is rather ballpark. If it were mine I would be giving it more attention, maybe with photos? @Ambull If you don't buy it and it's 55~60ft NB, please PM me. Maybe I can... share the cost of your survey with you, or something?

This is true for resistive-ish loads such as motors, mug boilers and tungsten lamps, but it's not the whole picture. For anything powering IT kit (laptops, phones) or most other voltage converters including LED lighting units, they're trying to draw the power they need. When the voltage dips, perhaps because something else is sucking on the same cable, then they will also suck harder. In numbers: suppose a laptop wants 90 watts as 4.7 amps at 19 volts, and you're using a DC:DC converter with 85% efficiency. That thing needs 106 watts input, so at 12.6 volts it will draw 8.4 amps but if the voltage dips to 10 volts (assuming it doesn't shut down) it will at least try to draw 10.6 amps to deliver the same amount of power. Beware also that this isn't enough to blow a 10 amp fuse for a good while, if at all. See also "We almost had a fire on our boat! Smoking wires" (youtub). Nobody hurt, it sounds like they learned something.

There are several ways to do reverse polarity protection when designing this kind of kit, and the cheaper kit does it the cheapest way. a blocking diode in the supply. When it's backwards nothing happens, but when it's forward the diode steals half a volt. a crowbar diode reversed across the supply. When it's forward, you get full voltage and the diode sleeps. When it's backwards there is a short circuit through the diode and hopefully the fuse blows. There may be sparks and burning smell, but most of the magic smoke should be retained so it's possible to repair the thing. no protection, which saves a fraction of a penny at build time. When it's backwards, all the magic smoke is likely to escape. Any equipment connected downstream may get its own reverse polarity challenge. You buy a different brand and are more careful next time. fancy stuff like the ideal diode or other active protection. or it's designed to accept AC, such as those MR16 LED spotlamps. It probably has a bridge rectifier which steals a volt, but it won't care which way it is connected. All that, and you have to know what the voltage actually is. Some vehicles run 24V but they're usually clearly marked. It's still best to not trust the thing you plug the kit into until you've checked.

As a professional finder of loopholes && strange corner cases, I love this! It makes me want to have 12V DC, as usual 240V AC, as usual 12V AC, as used (less frequently these days?) for halogen lighting in landlubber kitchens. MR16 and other lamps will cheerfully eat this. 240V DC Since I'm being silly, let's also have a high power audio amp with speakers that can be plugged in at various places around. Well it's AC and you can draw power off it when the volume's up... potentially also DC if that isn't being properly blocked. all in one vessel. Clearly labelled and safe of course, but just to freak out the RCD inspector. (Why would I do this if I were having to pay... maybe after I win the lottery and grow some strange hobbies) 240V DC you ask? I do know one person who did this in his house - I never saw it but he's a sensible, if slightly eccentric, technical chap. It was provided by solar panels, late 1990s? The switches in his toaster and kettle had long fused shut, which was inconvenient. He had to remember not to use the (electric) oven when the house was in DC mode, else the thermostat would fuse on. But all the existing (tungsten) 240V lamps were perfectly happy, and when the power grid dropped his was the only house on the street with light. He used the immersion heater to dump the spare power into the DHW when his (ex-telco standby lead acid) battery was charged (possibly even to regulate the charge voltage? not sure). This eventually went wrong, fortunately in a self-limiting way, because the tank started to boil ?. The steam bubble at the top of the tank allowed the immersion heater to reach a temperature where it unsoldered itself (as he described it - but I'm surprised there was no thermal fuse). Very bad things can happen when DHW tanks are boiled. I don't recall any mention of what happened to the batteries at this point.

Not me not this time ? but it could look a lot like it... I know that I've never seen 115V on a narrowboat. I'm wondering if anyone ever did. 110V is in use in the UK, e.g. these ugly great things, https://www.everydayweldingsupplies.com/draper-1kva-230v-to-110v-portable-site-transformer on building sites. I believe it is for the safety aspect of 110V power tools & light strings. I would guess that 110 ~ 120V is within tolerance for most things, but its always best to check the label. Lots of power bricks take 90~240V and US equipment would be happy with it, so it is an option. I have no 110V kit and unlikely to buy any. I wouldn't do it to my boat, nor suggest anyone else should. (What I actually woke the browser for is the perennial question of what to use for 12V sockets. I'm reading the old posts and making a little list...)

Suddenly curious: It had not occurred to me to run 115V mains. Does anybody, on canal boats? Then with what kind of, a NEMA 5-15? I tend to think that the places where the mains reaches should all be staying dry, but ? ?️ water and leccy are both tricky ones for finding their way where they aren't welcome... but I don't think I would want two inverters and four+ voltages kicking around on my boat.

~~~~ (later... will it merge my posts?) ~~~~ there is also 4. outstanding finance risk

~~~~ (post merge?) ~~~~ Here is one at https://www.thisismoney.co.uk/money/saving/article-2245780/Victory-couple-threatened-26k-narrowboat-loan-bill.html "Told we owed £26k even though bank knew it wasn't our debt': Victory for couple threatened with losing narrowboat home"

Threadwakey, in the context of things to consider for (private) boat purchase: Waterways World mag's 2020 Annual says (emph mine) so I wonder whether there is an advantage to having a lender during a boat purchase, for the purpose of them being in the same boat ? with outstanding finance risk. Complications, Fitout Pontoon says a Chattel Mortgage would be the tool, because the loan is secured on the boat, but I'm not seeing much when I Search The Fine Web Arkle & Lombard explicitly won't lend on residential (the private sale boats I'm looking at are probably not yet habitable) (in lockdown, brokers mostly only do viewings for residential)

I will here plead guilty to oversimplifying things I didn't understand. ? The boat builder I called (Collingwood? Someone advertising in WW mag) did outline tonnage figures and calculation, but from my point of view: the zero-VAT figure cannot be achieved with a narrowboat. It is therefore irrelevant for my immediate concerns and the details of the criteria didn't stay in my head.

I joined the RYA (personal, £47) for access to their legal helpline (waiting) & discounts. Thanks @TheBiscuits for the tip. The 50ft, I know little about except the owner seems like a decent chap. The 55ft I know less about, seller is in a big rush /!\ but I do want the extra length. Each is under £25k which presumably means there will be problems. I didn't want a "finished" boat anyway. Previously I had the impression that the VAT status was a property of the boat. One builder explained that only boats over a certain size (which basically means 60ft+ widebeam) can be zero-rated for VAT and anything else is 20%. Is the liability for paying VAT actually a property of the sale, and hence not relevant for private sale including where a broker is involved (boat not owned by a company)? And so also not attaching to the boat to encumber future sales?

When I break down the issues, do these cover all concerns? that I get legal ownership I can sufficiently prove that ownership later that I know about technical (mechanical, structural) problems and have some idea what they would cost to fix > VAT status is largely ignored for UK inland boats, but is critical for boats that travel to other countries. Probably not an issue for me then? But I'm very reluctant to risk crossing the tax man. If he ever comes after me for 20% then I have a serious problem... my concern is that I don't understand the mechanism of how or where VAT could be liable, and payable by whom.

What a heartwarming website! It says nothing has been stolen. ? Maybe it is broken or disused. It does tell me there exist Hull Identification Numbers, so maybe I want to find that... wouldn't be surprised if there wasn't one? Thanks... but I'm after 55~60 ft NB. I found one that's slightly short, sounds legit, and not in a hurry; the other is longer, cheaper and more scary.

I'm looking to purchase a boat privately and at a price that promises to be attractive, but there are alarm bells I don't know much about the boat yet no broker involved seller of one boat is in a big hurry (with a feasible excuse) I asked a random broker and "my" boatyard if they would act for me as purchaser, and they don't do that. The broker helpfully warned me to be very careful (!). I would have a survey, and I know I need the Bill of Sale... but I'm not sure I would know whether the paperwork was valid. I looked at and I see the warnings, > Ask for the Bill of Sale and recent invoices before anything else. Make sure there are no glitches. > The broker is interested in your money, first and foremost. Where money is involved, assume nothing. > I would rather make a private purchase where there is paperwork (licence invoices, the mooring invoice etc etc) all in the sellers name and at his address [...] get him to take you to his house to sort out the paperwork. > There are plenty of ways of showing 'ownership' evidence but a broker has no incentive to pursue them, [...] and the link to http://www.stolenboats.org.uk/Welcome.aspx and more warnings at https://www.canalworld.net/forums/index.php?/topic/109215-sunken-narrow-boat/&do=findComment&comment=2572753 Also what would I need to know about VAT status? I'm guessing the RCD, to the extent it might apply, isn't going to protect me; but being an honest chap I would need to comply if one day I sell it on.

Using mostly this first data source of three top search hits https://www.brighthubengineering.com/power-plants/20189-burning-coal-how-much-air-is-required/ says "around 0.332 kg of air for one MJ of heat", and (next page) coal fired power plants burning pulverised coal use 20% extra air to ensure complete combustion without heating air for no gain https://coalpail.com/coal-forum/viewtopic.php?p=81586&sid=cdb05b7b279e06a200febae320d5a639#p81586 on the burning of coal in stoves in houses, discussion of air input https://www.sciencedirect.com/science/article/pii/S2352484719308704 very detailed but TL;DR and air figures from my previous post, assuming the 5kW stove output fueled by coal assuming initially that the stove is damped down to minimum output and hence only combustion air goes up the chimney, but somehow we retain stoichiometry of full combustion assuming air enters the stove at 20°C and exits the chimney at 200°C 5kW * (0.332 kg / MJ) / (1.225kg/m^3) = 1.35 litre/sec 5kW * (0.332 kg / MJ) / (1.225kg/m^3) / 107.25m^3 = 1/22 hr (i.e. 0.04 ACH) 5kW * (0.332 kg / MJ) * 1005J/K/kg * 200degC = 0.33 kW This seems remarkably low. Maybe the output is hotter? Maybe normal stove air throughput is rather more than the 120% air supply used in carefully managed power stations? It's also possible the combustion air heatup is already accounted for in the (0.332kg//MJ) but my interpretation is that the whole megajoule would have to be recovered by bringing the exhaust back to 20°C. Then looking at the other unrealistic assumptions, Suppose only 66% of that boat is actually heated, which I could try to justify as subtracting the bow & stern (5ft each) and the bilges & floor (lower 1ft); and then claiming rather arbitrarily that a further 10ft of the interior is effectively unheated because the radiators don't reach / cupboards aren't heated / the ACH draught carries the heat the other way. 2(6ft + 10in -3in)(66ft -3in -10ft) + 2(6ft + 10in -3in)(9ft -3in -1ft) + 2(66ft -3in -10ft)(9ft -3in -1ft) = 158m² = 80% of 198m² 2(6ft + 10in -3in)(66ft -3in -10ft -10ft) + 2(6ft + 10in -3in)(9ft -3in -1ft) + 2(66ft -3in -10ft -10ft)(9ft -3in -1ft) = 131m² = 66% taking a reduced 2kW to heat the box. Then when the stove output is 5kW, that means 3kW must blowing through, indicating ((3 - 0.33) kW / 2.2kW) * (5/hr) = 6.1 ACH, not a huge change. which seems to support the ACH assumptions being around 50% of heat loss. So how much power can be saved and what's that going to mean? Assume a marvellously optimistic heat recovery of 90%, (3 - 0.33)kW * 90% = 2.4kW max saving With a "first pass home brew" heat recovery of 25%, (3 - 0.33)kW * 25% = 700 W "could do better" I should run the numbers again with 10°C outside. Then maybe I have to consider also humidity. but when effective stove output is regulated by opening windows ? or if you can't run the heater at 2.5kW (and less in warmer weather) then we're eating electricity but not achieving anything. The way I look at it this is: having an MVHR requires a heater with a modulating or averaging output - fluid fuel with a thermostat, or something else.

Some numbers which will tend to be more precise than accurate... these expressions will paste into GNU Units 2.19 so anyone can come back and re-work them. Assuming a 66ft narrowboat as a cuboid 6'10" wide and 9' tall, with 1.5" insulation with R(SI) of 0.85 picked from a list, ignoring the fact that bilges & non-cabin areas will be left cold, thermostat is at 20°C (and that's effective across the whole place with no cold spots inside) and its exactly freezing 0°C outside, 2(6ft + 10in -3in)(66ft -3in) + 2(6ft + 10in -3in)(9ft -3in) + 2(66ft -3in)(9ft -3in) = 198 m² of interior surface total R(SI) is 0.85*1.5 = 1.275 degC m^2 / W 20 degC 198 m^2 / 1.275 RSI = 3.1 kW for heating the box with zero ventilation I don't have any air changes per hour (ACH) figures, but I can guess and it's a starting point Taking the same internal volume (ignoring unswept volume for cupboards, tanks, mattresses etc.), 5 ACH at 60% of the swept volume based on numbers that pop into my head after doing minimal research, and taking figures for heat capacity for air at given humidity, ACH figure will greatly depend on the wind. I suspect that, due to indoors combustion, boats are made with generous ACH. I've conveniently put the humidity close to zero by declaring that outside is frozen I don't understand GNU Units' "airmass(alt)" formula so I'm going with this page and taking air at 1.225kg/m³ (6ft + 10in -3in)(66ft -3in)(9ft -3in) = 107.25 m³ swept volume 5/hr *60%*107.25m^3 * 1.225kg/m^3 * 1005J/K/kg * 20degC = 2.2kW for heating air as it passes through I need another section for "air heated by the stove and sent up the chimney", which I will tend to assume is additional to the ACH figure, but we are at least in the ballpark of the 5kW output stove.

It's (now) on the list I stuck in my profile here, so I don't forget. I have a promise of mooring but no boat yet. I'm far enough away from London ? and the EHU rate is quite reasonable - only a smidge over Octopus residential tariff. That is basically my plan. The currently promised mooring has some issue with me doing welding (?), but until I have a definite boat (hence length) then it's open to change.

Is it a pretty blue flame? Then I know what'll be causing it... I can't solve all the problems at once, so I was planning to start with the ones I can make a difference to. I also can't discuss them all at once... I'm willing to try, but I doubt I can be productive. This property I'm in (with the oversized MHRV) also has an ASHP, and it is a noise nuisance. I think the noise is mostly conducted vibration from the fan, because I hear it spooling up and down. I'm told the compressor is constant speed. Nobody is looking at its actual efficiency, but lots of people are crowing about how efficient it is. (Somebody did look at efficiency of a related system nearby and it's bad enough to suggest a major fault. From here it's minor local politics and I'm bailing out.) My thoughts on this line had gone as far as wondering whether it's better to source heat from a skin tank or the bow thruster tube. I don't know, it might depend whether the bow thruster can run slow and quiet. And whether it will damage the bank/pilings while doing so. For me the need for 24kW hr per day (no cruising) looks too ambitious, unless I have EHU, so I wasn't expecting to have WSHP in my boat any time soon. However I would expect to be able to retro-fit one when circumstances change: all useful heat should go into water at some point. There is also the interaction of "running the engine for the heat pump" and "waste heat from the engine", which is beyond what I can juggle in my head. I don't have data (yet) on the thermal inertia of an engine system but it seems relevant while the engine is warming up When considering efficiency there is the question of driving the compressor off the engine (like a car aircon unit) ? vs electric motor drive from the generator being spun by the engine ?, and worse a battery charge/discharge cycle and inverter between. Why would you do the latter? Because you don't want two heat pumps ? unless you've done the maths first. Would a car aircon unit interest you, size-wise? I've no idea what temperature ranges they can work in, but if it will cool that cabin to 15C when it's 45C outside then it'll work in some weathers. I've seen a car aircon under test take the cabin down to 9C & suspect it was power-limited at that point so I don't know if it would reach lower. Another thing about heat pumps is the entire plumbing speciality that goes with them. Once it has been installed I have to call somebody in to service it or make changes. It's a cool topic but that's about all the thought I've given it so far... ...for the future, when diesel engines are obsolete, an all-electric boat will run just fine on fusion power! ?

I will want to talk about generators, and no I don't want to annoy neighbours or anyone else. However we're getting off MHRVs & ventilation so I'll reply on another thread in a bit. Thanks all for the thoughtful comments!

All true, except probably not running a generator while on EHU unless I'm testing something. Burning fuel to make electricity will also make heat and I would like to catch more of that if I can. Another of those stories for another day. Yes, I don't think I want 4 inches of insulation on a 6'10" wide boat so it has limited potential. I did calculate heat loss from surface area / U-value, it was a few kilowatts but I didn't keep the numbers. Any holes or bridges in the insulation will make a big difference, but I do have access to a thermal camera. I haven't done the equivalent for air(heat capacity / changes per hour) and it's another fair question. Can anyone give estimates for how many air changes per hour a passively ventilated boat will give, under assorted wind conditions? Presumably it's fair to include air going up the stove chimney. In the interest of science I should do all possible calculations before the experiment! What I expect not to have easily available is actual heat output from solid fuel stove, but any kind of electric heating would be offer a reliable comparison and I probably will have that. It may be a couple of years...

I will but don't hold your breath - no boat yet, and I've seen some of the threads about state of the market. ? Also I'm not the fastest project executor, and that's one of my larger worries. Any tips on this would be most helpful! Also a fair comment, but in this case it's more laziness of expression than lack of understanding. What I was trying to do is illustrate how I would protect boat occupants from unplanned battery exhaustion, when the MHRV relies on DC. The lazy datapoint I'm using is inverters, which tend to shut down at 10v input. I believe that taking a domestic battery down to 10v or 11v for a brief time may do it some damage, but less damage than if it sits like that for a week. I believe a traction battery treated the same way will have more damage... I've learned the hard way with car batteries that I've been irresponsible for ? and tried to help several others following the same path. For either of them, when they're badly discharged (by any measure) you have to stuff some joules back in ASAP. When they are discharged, and that's your only DC source, it does make perverse sense for a control system to continue running the microcontroller that's monitoring it (even though it's continuing a discharge which is degrading the battery), provided that microcontroller has some way to summon the human and charge the battery. After all that though I come back to: electricity is essential, so I plan to have several buckets of it. Another story for another day. LTO batteries are what I would buy if I was going out today for them. I do need to learn more about the various types of lithium battery, and I have ongoing discussions with a friend who works for a company that puts some kind of lithium ion battery in trains. This article (paywall / first fetch free) https://www.magzter.com/article/Lifestyle/Canal-Boat/POWER-TO-THE-PEOPLE is a good indication of my kind of direction, but I don't think I would tie it to a lead acid. Another thing that'll make y'all say I'm crazy: that hob which isn't going to run on LPG... I'm planning for an induction hob ? so the MHRV will be in good company. I need to do more research, but I'm not frightened of electricity shortage.

This is universally what I've read, and it makes perfect sense with a wood/coal stove. What I want to do is avoid burning fuel to make heat which I then throw out the window - for me, that's one of the horrors. So it requires two things: not throwing heat out when I can keep it in (hence MHRV) and having heat source(s) with a total average output that can modulate from "it's getting a little chilly today, maybe I'll put the heating on" all the way down to "I'm not going outside in that without four layers of thermals", ie. temperature differences indoors to outdoors from say 4C to 40C. That's a separate problem. What summer usually requires is a good through draught of nice cool air. This is something I've given much less thought to, so far. I'm hoping that I won't want air conditioning (!!) on my boat, because the power budget is silly and cannot so easily be supplied by burning stuff. But if I did, an MHRV (or ERV in this context) will serve the purpose again. If a place is actively cooled, the heat exchanger will serve to cool the hot, fresh incoming air. There will be condensation where that happens. Then the cool, stale and dried air has to be pushed through the heat exchanger on the way out. Some relevant Youtube vids which affected or illustrate my thinking airtightness testing of a passivehaus HRV vs. ERV - What's the Difference? Hmm, it looks like I've misunderstood ERVs a little, but I don't think they're so relevant in our climate. This process is a game changer for building an efficient home, The vid I mentioned in my OP: This Insulation is BETTER than Spray Foam!! They also use air-sealing with positive pressure to keep out fine dust from dust storms (see at 6:30). Foam Free House - Is this Silly, or should we ALL BE BUILDING LIKE THIS? is about going to great lengths to avoid spray foam and EMFs. I'm not fanatical about this sealing & filtering lark, and I have some concern about the dangers of bad spray-foam jobs, but I will take the ideas and use the ones I like.

Oh I did, and I'm delighted - thanks for that. I just can't type fast enough. ? As I said, What I meant there is: if not for your information (post #4) then I would have to have a serious re-think of the whole project. During winter, traditional fixed ventilation gives me flashbacks to single glazed houses with inadequate heating that struggles to keep the place warm - while burning £££s. What I'm imagining is a hygge little place where it's cosy inside and not gobbling my money to do it. So on to the BSS part, This is hugely reassuring that I'm not going to end up with an immediately uninhabitable boat. I believe I have sufficient education to avoid earning myself a Darwin Award, even though I'm cautious that I don't have practice and skill in boat fitting. Initially I'm taking this as "it is theoretically OK to have a sealed boat with MHRV", but there is the follow-on question: is the average BSS inspector actually going to understand that and agree, or am I likely to have a fight on my hands to get that recognised? For summer mode and while I'm absent from the boat, I think passive ventilation is also a good thing if it is optional. I can imagine a BSS inspector freaking out to see ventilation holes that can be sealed airtight.

If I could afford a bungalow and even wanted one then... I wouldn't be on this forum ? So that's a fair warning. I'll take it and bear it in mind - if/when I want to sell up, I probably have to be able to turn it back into a boring olde-style boat or take a financial hit. Another thing I like from this thread, New house builds have this horrible habit of hiding things behind panels which don't come off. Build it in, cover it over and glue the lid on. How am I going to service that when it breaks? So overall, yes this is a fair observation (repeat from above) I'm not completely new to boating, but haven't owned one directly before now. Also I'm a confessed idealist. Thought projects are cheap but there are limited circumstances where they can prove anything either way. It has to be tried to see, and when the available technologies improve it is probably worth trying again.