IanD

Large parts of the towpath were blocked off all the way down the Nine, two of the crew set off to walk to the next lock and couldn't get there, eventually met us 3 or 4 locks down at Duke's.

No, we got through later that afternoon after CART fixed the paddle closed. Didn't get eaten by locals, almost drowned under the usual top gate waterfalls...

Or lead-carbon which are supposedly perfectly happy not to be taken back to full charge every time. Also note that if you had a 15kW generator and a 30kWh battery bank, it would only take about an extra 10 minutes of running to get the tail current right down...

Perfectly possible, by the time passing moored boats and locks are taken into account I suspect the average power over a day for a narrowboat is in the region of 2hp. With a 15kW (20hp) engine-driven generator (this is *huge* -- even the Integrel one is only 9kW) you'd only need to run the engine for about one hour a day to put this back, even allowing for losses. The hybridmarine system is about half this power (7.5kW/10hp) so would need to run for about 2 hours per day.

The references that were quoted earlier in the thread, IIRC this came out to about 20% total loss from power in to generator to power out of motor. If the losses are worse than this then the fuel saving will be smaller. With a bigger generator the fuel saving will be bigger. However it's clear that the "hybrids never save any fuel" statement can easily be wrong, which is the point I was making -- running a 43hp diesel at 4hp for cruising does give lousy efficiency, even worse when passing loads of moored boats nice and slowly (maybe 1hp), and idling in locks is obviously just pure wasted fuel (0hp). My guess is that by the time this (and solar panel power) is taken into account the real fuel saving with a hybrid will be something like 30%, maybe 40% with an optimum-sized generator -- which still doesn't pay back the installation cost, unless you were already going to have an electric-heavy boat.

Sorry, I didn't make it clear -- the 22" x 13" numbers (column D) were the only published accurate data I could find for absorbed prop power (64kW max at 2800rpm) vs. rpm, I then scaled these to the Beta 43 maximum output (43hp at 2800rpm) to get the numbers in column E, which were then used for calculations -- according to Beta this would probably need an 18" x 12" prop. Column I shows the maximum power vs. rpm read off from the Beta 43 data sheet, then column I shows the "spare" power available to drive a generator (and alternators if fitted).

It's more efficient to run an engine at higher power for a fraction of the time (also charging batteries) and use electric power to fill in the gaps -- see attached spreadsheet for an example with a Beta 43. At all revs except close to maximum there's a lot of "spare" power available above that absorbed by the prop. Running all the time with 4hp to the prop at 1400rpm consumes 1.5l/hr, engine is running at about 15% of maximum power at these revs so thermal efficiency is about 19% (compared to 34% at full power and load, 43hp at 2800rpm). With a generator absorbing another 10bhp engine consumption will be about 3.5l/hr with about 28% efficiency, but it only has to run for one hour in three (the 10hp into generator for 1 hour comes back from the motor as 4bhp for 2 hours assuming 80% efficiency) so average consumption is 3.5/3=1.2l/hr, giving about 20% saving in fuel. This also shows that a 10hp/7.5kW generator is really too small for a Beta 43, the engine has 15hp/11kW "spare" available all the way from 1000rpm to 2400rpm, with 20hp/15kW available at a 1400rpm cruise -- a bigger generator would give bigger fuel savings by running the diesel at higher efficiency/power for even shorter times. The main problem with hydrogen is not safety, it's lousy efficiency -- it's acting as an energy storage medium like batteries, except that the overall "power station to wheel" efficiency is about half so needs double the amount of energy. Given efforts to minimise energy consumption, this makes a nonsense of the idea...

Actually if you read the articles (they're both good) you'll find it agreed with what I said earlier; given the low power outputs and speed (and locks) in normal canal cruising a parallel hybrid will give significant fuel savings, even allowing for all the losses -- maybe not as much as the 50% in the article, my guesstimate was about half this. It also says: "The powerful generator and large battery pack of hybrid systems are enablers for more extravagant lifestyles. It is these lifestyle issues—lots of house power and substantially reduced engine run times, along with the concomitant silence and freedom from exhaust emissions—that will ensure the success of hybrid systems. The greater the house loads and the more extravagant the onboard lifestyle, the more attractive a hybrid becomes. Any efficiency gains will simply be a bonus." In other words if you want a boat with a big battery bank and the means to keep it charged to run electrical appliances, a hybrid is a good solution because you'll already have paid for a large part of the electrical system, and you get silent locking/cruising as a bonus -- always assuming your pockets are deep enough to pay for it.