IanD

You're doing a lot of presuming and assuming. My comments about EV reliability, running costs and lifetimes are based on facts from hire companies and fleet operators. They are a lot simpler than ICE and have a lot fewer things to go wrong in the drivetrain, which is often the expensive failure that leads to a car being scrapped.

Fischer-Panda are very expensive for generators (especially 48V) which have some reputation for being unreliable, are higher speed so need more maintenance, and are not really designed for keel cooling, and for high powers their inverters are more expensive than Victron and need paralleling up. Lead carbon batteries cost more than traction cells but less than LiFePO4, are better than traction for partial SoC operation and absorption but not as good as LiFePO4, and are as big and heavy as traction cells -- LA weigh about 3x as much and need a lot more space. It seems to me that if you want the lowest cost for a big bank (e.g. parallel hybrid) 2V traction cells are the right option, if you want a serial hybrid without long charging times and can afford them then LiFePO4 is the right option. Lead-carbon are the in-between solution, not as cheap as traction cells and without the advantages of LiFePO4.

The article quoted earlier (from a study funded by ICE manufacturers so may not be unbiased) had the CO2 difference at manufacture as 10 tons and the CO2 break-even mileage as 50k miles -- not forgetting this was for a big heavy Volvo, not a small city car. None of which changes the conclusion that even in the worst case (power from fossil fuels) the lifetime CO2 emissions of BEV are much lower (less than half) than ICE. If the numbers are closer to yours and/or the power is renewable or the BEV lifetime is longer (all likely) the difference is even bigger.

Which "rest" do you think is unreliable? If you doubt something, please provide evidence that it's wrong. If it's valid, I'll agree with you 😉 Cars are scrapped when something expensive goes wrong or wears out, which is often (not always) the drivetrain, or when maintenance/fuel costs get too high to justify carry on driving it around. These costs are lower for a BEV and the drivetrain is more reliable (evidence from car hire companies, maintenance costs are less than half) so they're likely to have longer lifetimes.

If you're running from an inverter it's more important to have an efficient drier than a fast one -- the newest heat-pump driers use about half the total energy to dry a load (and are not vented) but take longer to do it. If you're running from a Travelpower then faster is more important than efficient... Combined washer-driers can dry a smaller load than separates (and take even longer) and are also complex and have a reputation for being unreliable, but they do fit in half the space. There aren't many heat-pump combos...

Very unlikely to cause a freezing problem -- a 4kW heat pump would cool 1kg of water by roughly 1C per second, and there's an *awful* lot of water in the canals... Agreed about the generator -- my plan was to put it (and fuel tank/silencer/Ebersplutter) in the bows under a short tug deck. All the noise and exhaust fumes as far away from.the steerer as possible...

Bottom plate will never get below 4C...

As I said, I was lazy and only spent 5 seconds looking, not 10. Answer for the UK is 125k, other countries are more. BEV are likely to have longe lifetimes than ICE. Conclusion is unchanged...

I was lazy and quoted the first number I found. Spending an extra 10 seconds gave numbers for different countries, see above -- 125k for UK, some countries are higher, some lower... All this also ignores that BEV are likely to have longer lifetimes than ICE because there's less to wear out and maintenance/repair/fuel costs are lower -- not a guess, based on facts from the hire car business.

Go and look for yourself 😉 Took me 10 seconds to find an old answer to this: 11th March 2011, 13:02 model/ country. US: 160,000. Australia: 145,000. UK: 125,000. Canada & France: 115,000. Rest of Europe: 105,000. Japan: 70,000. Like the article quoted elsewhere said, the CO2 break-even point (including manufacture) for EV compared to ICE could be 50k miles, every 50k above this puts the BEV about 10 tons of CO2 ahead. And what matters here isn't really the UK, it's what happens worldwide.

The only thing that will help with this are canalside charging stations, preferably using green energy, and minimising energy consumption. No solution is perfect, the question is whether it's better than the existing one. Don't forget that all the canal boats in the UK put together contribute 1000x~10000x less CO2 than all the cars do, so you could also say that UK-wide CO2 reduction isn't really a strong reason to go hybrid on a boat... Electric cars (not hybrid tax fiddlers) are a different matter; cars generate a *lot* of CO2, and even if the energy comes from fossil fuels the "well-to-wheel" efficiency is about double that of ICE (so half the CO2 emissions). If the energy is green (solar/wind) the situation is obviously much better still. The numbers are out there, go and look, Google is your friend 😉

20kW is still more than some people are saying is "OK" for series hybrids (Finesse/Shine are 10kW IIRC which I don't think is enough) -- it's not as much as is usually recommended for diesel engines but this is output at the prop and there are no gearbox/alternator losses, 1kW per ton at the prop is what is normally recommended for displacement boats and a typical narrowboat (up to 60 foot?) is 20 tons or less. Anything above 20kW for a single prop gets *really* expensive (makes the Bellmarine look cheap...), can't be done from 48V which is the highest standard inverter/charger voltage, and everything needs treating as HV for safety which is a big pain for installation and testing. The reason for a 230Vac generator instead of a 48Vdc one is that they're much more widely available, and on a boat which relies on AC power (fridge/freezer etc) you have some AC redundancy while you get a dead generator or inverter fixed. It also means the battery charging can be completely controlled by the master BMS in the battery packs (via the Quattro as a slave) to guarantee both protection and lifetime, this is much more difficult if a DC generator connects directly to the batteries. A normal diesel has no drive if the diesel fails, a series hybrid has no drive if the motor/controller fails, so there's a single point of failure in both cases. The parallel hybrid is the winner here, you have two sources of propulsion -- OTOH you only have one source of 230Vac (the inverter). Depends which you think is worse, being unable to move or having no mains power and a freezer full of rotting food... 😉 Like I said, cost is not the reason for doing this, silent cruising and (maybe) future-proofing (diesel-free propulsion) for when charging stations appear is.

Running a water source heat pump with CoP of 4 to heat the boat (are these available?) would consume about 1kW when it's running to put out the same heat as a 4kW Ebersplutter/Webasto/stove.

You're almost certainly correct. Ripping out and replacing an existing [anything] very rarely makes sense if it's still working. The BYD batteries specify operating temperature range down to -10C; sitting inside a boat in the water in the UK they'll never get this cold, even if the canal surface freezes over the water underneath doesn't go below 4C. https://www.bimblesolar.com/BYD-LVL-15.4

try entering "average car mileage before scrapping" into Google, it's really not difficult... 😉 The point is that so long as the average is much higher than 50k miles (which it is) the exact number doesn't matter, EVs win. I can read too, and that was exactly my point -- *always* check where a "report" came from, very often it's biased (not difficult to do with cherry-picking of numbers -- not that I'm saying they did that, but they have form...) or at the very least funded by companies with vested interests. In this case, you could say the vested interest is to get people to carry on buying their ICE cars instead of Teslas... 😉