-Stolen-

Our 4-stroke 4 horsepower Mariner petrol outboard was stolen from our shed on 22/04/2019, along with a similar, slightly older model of the same engine that developed a cracked head. From the Caracruiser refit in 2001 these two engines had propelled our boat for 18 years, for more than 15 trips on over 20 different rivers and canals of England and Wales.

We considered replacing the petrol outboards. Our 4hp models had been powerful enough, if a little noisy. It is, however, not so easy to find throttle remotes for smaller outboards. Smaller, single-cylinder like our previous ones are also quite noisy. We investigated some twin-cylinder options, but this means upgrading to over double the power and a significant increase in weight – not ideal.

Planning

Oddly enough the thieves had left our old 48lb thrust electric outboard from the late 90’s – as if it was some sort of hint. The motor had been bought for a smaller boat, but we had used it to power the Caracruiser before and it could just about push it to the canal speed limit. The bigger issue was powering it for more than a few hours. Since then the price of batteries and charging options had fallen quite substantially. Could this train of thought prove to be another wasted experiment, or did it now have a chance of being a feasible source of propulsion for a prolonged trip?

Our free time over the next couple of weeks became more and more occupied with research. We started looking at the required components:

• Solar cells & charge controllers
• Motor controllers
• Different battery options
• Electric outboards

We needed to be able to produce enough speed, enough duration and enough charging – within the confines of the size of the Caracruiser. I even worked on a spreadsheet to try and help calculate range, required solar output and potential maintainable speeds based on different variables.

Our decided approach:

• Bison 100lb thrust electric outboard – twice the power of the previous electric motor – should reach canal cruising speed without using anywhere near max power
• 2x 310W solar panels – together they will use up most of the available roof space, without obstructing the hand-rails.
• 2x 110ah deep-cycle AGM batteries – the most cost-effective option at the moment
• A motor controller from china – for switching forward/reverse and controlling speed
• A solar charge controller from Amazon – Allows for charging lead-acid and lithium-ion batteries for future-proofing