jbzoom

Smaller diesel, higher efficiency and less pollution for now. Running on TVO or similar in a few years, made redundant by faster charging, higher density and cheaper batteries by the time it's due for replacement. Can be cocooned and made much quieter than a larger engine.

You're a bit dogmatic here - the torque is less important on a boat, but it still reduces the time a propeller takes to get up to full revs in an emergency. My comparison was a 40 hp diesel running a heavy alternator load - say 200 amps - versus a 20kw electric drive. 40 hp is pretty much 30kw. The alternators alone, with a charitable 60% efficiency, would absorb 4 Kw and the drive train maybe another Kw, resulting in around 25 Kw at the prop. The 20Kw electric motor should deliver 20Kw at the prop and take maybe 23 kw out of the electrical system - most are specified with peak ratings higher than nominal, so even higher kw bursts are feasible. A 5kw difference at the propeller will make no difference on the canal and a minor difference of perhaps 1 mph in top speed on the river, which no-one does with a diesel, because they're worried about overheating and noise. Several US electric boat vendors use serial LiFePO4 installations and Victron have all the necessary control equipment to do it available in the UK. Not cheap but, in my opinion, worth it for mostly quiet cruising, with maximum use of shore power and solar for charging and the genset cocooned for those occasions when it is necessary to use it.

The series hybrid offers a path to the future - for now a diesel genset is needed, but much smaller than in a direct drive or parallel hybrid. Eventually it can be run on bio- or tvo-diesel of replaced with whatever greener technology comes along. Batteries, solar panels, controllers etc. account for most of the costs.

The need for 40 hp or so diesel engines on rivers is usually for short bursts of manoeuvering, where full torque is needed and delivered only at higher revs. Even then, after taking account of alternator and gearbox losses losses and the alternator load the effective delivery at the propeller is not very different from a 20Kw electric drive, which generates full torque at low revs. A 10 Kw genset and decent battery installation can support a 20kw motor drive, usually run at a fraction of that, with more electric household applications or an extended river trip with the washing machine, induction hob and immersion coil turned off. The cost of marine diesel gensets varies relatively little between 6 and 12 kw, based on the Betagen price list. Four Lithium Iron 12v batteries can be connected in series to deliver traction power or in parallel to deliver 12v. Serial Hybrid is the future and can work well in narrowboats at 48v, much safer than BEV power packs.

My family were the first owners of this Barney Boat when it was called Bandit. Later named Goshawk and Rainbow, before Lil'Fin. Would love to track down boat or current owners

Exactly

The advantage of serial hybrid with a diesel genset is that the diesel engine can be run on biofuel until a viable alternative low carbon power source is available. I agree, that may not be hydrogen, but I'm also sceptical about the viability of installing a supercharger at every water point.

Victorian newspapers were keen on Latin bylines for their correspondents, e.g. Hortulanus for a gardening correspondent. Presumably either the BWB or an predecessor had a publication with gardening notes. Can't find much on Google, as few old newspapers are content-searchable, did find one in Brisbane - rather unlikely to have reached the canals.

The IWA has a team working on the path towards zero carbon. The best planning for new boats is serial hybrid. Battery technology will take some years to become affordable for more than a few hours cruising and a network wide charging infrastructure will also be a huge challenge. A diesel generator, complemented by solar can charge batteries that support electric traction as well as domestic requirements. The diesel generator can eventually run on biodiesel or be replaced by a hydrogen or solid oxide fuel cell when these become viable. Engine manufacturers are promoting parallel hybrids, just like car manufacturers with "plug-ins", because that gives the internal combustion engine the biggest share of the budget. By contrast, a 3 to 6kw diesel genset and a 20Kw electric drive is a better solution, because a canal boat typically uses only three or four kw most of the time with full power used only in brief bursts, to stop the boat or negotiate a tricky river entry or exit.

Where the originals are beyond repair a few more of these could become a very distinctive feature of the Manchester Bolton and Bury restoration.