Why don’t you get all-solar narrowboats?

It sounds great, for sure. A narrowboat needs only 1-2kW to move along (once it has begun moving) thus a 20kWh battery pack could sustain 5-10 hours travel (presuming standard lead-acid tech ie 50% drawdown before recharge) and presuming the battery is not used for anything else aboard (though in reality most electric-focused boats use it for domestic purposes as well so the battery and solar system has to support that too)

However, solar is not so reliable in the UK. There are not that many truly sunny days here and no matter what solar proponents say, if it’s cloudy and overcast, the resulting power is much less than optimal. Only in peak summertime are you likely to approach the solar panels’ maximum output and even then only when the sun is high.

In spring and autumn, any solar is very variable and in winter it’s negligible plus the hours of daylight are much shorter too and the angle of the sun much lower (It’s not always possible to angle the panels at the sun and even so, the other factors mean the resulting power will be far less than in summer).

On an average 57 foot narrowboat you have space for about 2.3kW of solar. That’s calculated as 40 feet / 12m usable roof length at absolute max, assuming you don’t store anything else up there (which most boaters do) and that you don’t want to get on the roof during lock maneouvres (which again most boaters do) x about 1.6m width which you don’t want to overhang else the panels may get shredded when you go through some bridge holes or tunnels.

Using high output 400W LG Neon solar panels (1m x 2m dimensions), you’ll get 6 panels max = 2.4kW maximum theoretical output. So you’d need an hour of optimal sunshine to provide 1-2 hours of propulsion. Thus at the height of summer, the panels might provide sufficient motive power as it was used but none to recharge the batteries as well.

At any other time, you’d have to let the panels charge the batteries for longer such that in spring and autumn it could easily take several hours to recharge for an hour’s worth of movement.

Without an additional (conventional) generator therefore, pure solar on a canal narrowboat is only suited for weekend breaks and day boats (see vlog 168) but not constantly cruising liveaboards.

That said, there are very few occasions when a bow thruster would really be needed. All the navigations on the canal, even the tight corners can be easily turned by using the tiller, as can most maneouvres such as mooring. A thruster could come in handy for tight spots in some marinas but generally it’s not a necessary item but a luxury so it’s not on my “must have” list.

Portable electric “trolling motors” are often suggested in the comments on my YouTube videos but I’ve never seen a narrowboat with one; I think it would be a bit ugly and awkward to have one mounted on the bow plus it could cause an obstruction in the locks (potentially getting caught on the gates etc)

You do increasingly find hybrid boats on the canal (see vlog 69 I did about just such a craft and also vlog 244 which was all about electric boats vs diesel) which combine a diesel engine or generator with an electric motor and large battery bank so that the diesel can supplement any input from solar.

Unfortunately there’s no charging infrastructure on the canals other than in marinas (though I one of the Welsh canals has power points for a fleet of electric hire boats – see vlog 169 – but this is unusual) so a generator is absolutely neccessary even if it’s just the engine – standalone diesel gennys are ridiculously expensive – plus a massive battery bank which is expensive, weighty and requires maintenance.