Felonious Mongoose is the narrow boat equivalent of a Toyota Prius - it has an electric engine to run quietly and a diesel when more power is needed, or when the batteries need charged up - though whenever possible we charge up from the mains.

Design and Build

Felonious Mongoose is a 60 foot narrowboat, designed for two to live in comfort, and comfort includes silence.

The three most important features of her design were silent running, "go anyhwere" (or nearly go anywhere) and comfortable year round living for two.

The propulsion model was that of a diesel electric submarine.  Electric drive for silent running, and a diesel to charge the batteries when needed.

The internal design actually came last - though was probably the easiest bit, because the Braidbar "Try before you buy" boat Skye was so close to our ideal.   Years down the line, this is still the case.

Choosing the Propulsion 

We decided very early in the build process ( about ten years before any steel was cut) rthat we wanted silence.

While there are other ways of doing it, we decided on a parralel diesel electic hybrid.   The aim was to cruise as much as possible with the electric motor, but have the diesel available for charging and when additional power was needed.  An additional benefit would be that the diesel would be working much harder when it was running.

At Crick 2008 Graeme Hawksley of Hybrid Marine and Beta Marine showed their hybrid   -  at which point I stopped trying to source all of the bits separately.

So what we have is a Beta 43 diesel, with a charging capability of somewhere between 8 and 9 kilowatts, and a maximum total output of about 30 kilowatts, an electric motor with a maximum output of about 10kilowatts, and an 875 amp hour 48 Volt battery bank.   (3500 amp hours if you convert it to 12volt, and somewhere about 4250 if you measure in the way leisure cells are measured.)

Choosing the Boat Length 

We wanted comfort for two.   With the list of things that we wanted to fit, a 57'6" boat was needed.  As we lose about 2'6" into the battery compartment, this brought us to 60'.  

This may preclude us going through the Salterhebble locks   -  and will certainly mean that the first time we do them, we will go uphill.  

For this, as with anything to do with the Pennine Waterways, Martin Clark's site is an invaluable source of information.

Choosing a boatbuilder

To my mind there are three reasons for going for any particular builder - and if any of them are in doubt, go for someone else.

Can you relate to them?

Can they build what you want?

Are they financially stable?

Braidbar Boats provided a very clear yes to all three of these.  

The "Why Braidbar?" page goes into more detail.

An Independent View 

Kevin Blick (consulting editor of Canal Boat magazine) did a very fair assessment of Felonious Mongoose.

Kevin made the comment that the financial justification for the hybrid construction would need to wait to see how battery life went. He was totally right.  

Seven years on, the batteries are lasting OK  -  capacity has dropped a bit, but I think things are going fine.  

If I moor somewhere without mains power, I now need to run the diesel after about four or five days of domestic power consumption where they used to last for seven.  

It is rather good not to be adding to the morning and evening diesel chorus that is such a down side to boat rallies!

I have travelled about 8000 km, and have run the diesel for less than 700 hours.  

The photographs for the article (and many more besides) were taken by David Oakes