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River Speed Boat

15kW Belt Drive 10 custom

This 1950’s 4 meter wooden speed boat was built with a 10hp Ford side valve engine. But years gone by has seen the engine become uneconomical to repair. The owner opted for a re-power and decided on a B-Drive system. To suit the unique power requirements of this project, we modified one of the aluminium frames to take a larger liquid cooled ME motor, adapted the direct shaft coupling, and fitted the original coupling to join the prop shaft with original propeller to the new unit.

Install Specifications

The technical capabilities after the upgrade to electric.

Cruising range (nautical miles)


As the boat and new system are still being trialled by the customer for speed tuning a range and run time figure is not yet available. With the lithium upgrade complete we will update the figure. But until then at least, the boat is getting some great use after the years spent ashore.

Peak power


This ME1616 motor has the capabilities of pushing more than the limit on this project but with the small prop size and lightweight nature of the hull, the peak will not likely be met unless increasing size and speeds of the propeller. But for this, it is ample for the customer. With the current setup of the batteries, the maximum available power is 15.5Kw. Enough to get the boat planning. A plan to make a custom lithium pack will unlock the full power rating of the this motor.

RPM range

0 - 3000

This 0-3000 is the capabilities of the motor, and we can programme the rev limits to suit the build. In this case it was to the final prop speed that was to match the original 1:1 reversing gearbox and 10Hp Ford engine. A target shaft speed of 2,500 RPM was specified so the motor was set to the safe and optimal limit of 3,000 RPM.

Going electric on a River Speed Boat

Motor Selection

A liquid cooled version of the 10Kw motor used on our B-Drive10 was used on this project. The liquid cooling allows the motor to run harder for longer, increasing its continuous and peak power ratings. This increased power was needed for the boats planning requirements. This motor was fitted to the B-Drive frame and running a 1:1.17 ratio belt pulley had a final shaft speed of 2,500 RPM and motor output speed of 3,000 PRM.

Battery and Charging

Having undergone a stunning restoration by the owners the best solution to the batteries was Lead AGM - explained below;
The best solution to power the boat would have been to use LiPO4 batteries, due to their light weight and high output current, but cost was prohibitive. So, lead acid AGM batteries were chosen as the energy storage solution in the interim (until lithium batteries become more affordable). Four Yuasa L36-AGM batteries were fitted in series to give a nominal 48 Volt output
- words from the owner -

First run - electric power!

The first run of the boat, with the new propulsion, showed that the output was not quite up to the potential, the boat could only achieve 12 knots, a shaft speed of 1600RPM and electrical power consumption of 8kW. The excellent support offered by Lightning Craft was requested and Josh provided a solution to have the motor controller tuned using a remote (mobile 4G) connection while the boat was on the water. This tuning enabled the controller to get as much out of the batteries as possible (15.5kW)
-words from the owner -

Boat Owners
Robert McPhee and Trevor Deacon
Boat Owners

"Lightning craft offer a very flexible design capability, they have significant knowledge and experience of the system and the support they offer made them the best choice for this conversion."

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