Where the power goes – Part 1

We have travelled more miles in March than January and February combined – hardly surprising, Cheryl has been taking the helm a bit more.  Actually this has allowed me the chance to take some speed/power readings to gauge the performance of the propulsion motor on long straight stretches of the Grand Union canal.

I am pleased how little power the boat needs to cruise, less than I estimated when I was designing it and selecting the motor, batteries etc.  One thing that is obvious to me as I cruise is just how much more power it takes to cruise faster.

I can see second by second exactly how much power the motor is using, how much power it is pulling from the batteries.  It is really obvious just what a waste of power it is to try to go fast.  A good thing, because going slowly does less damage to the canal banks, and we have more time to enjoy the wildlife as we pass.

KW vs MPH for canal cruising

Cruising at 3mph feels nice.  3.5mph is really as fast as one should travel on most canals but it uses more than twice the power of 3 mph, so seems hardly worth it. The moral here is just because you can, doesn’t mean you should.

When we pass moored boats we slow down and our power drops to under 1 KW.  When we travel through locks we use almost no power because the motor only uses power when turning the propeller.  The Stoke Bruerne 7 locks used just 14.8Ahrs.

For people who prefer figures here is the data as a table.  I have included Amps, because most narrow boaters think about battery power in terms of Amps.