Electric Motors - Technical Information
Materials & Construction
Our Electric Trolling motors are constructed from strong materials including a strong anti-corrosive composite shaft. The seawater models carry a sacrificial anode to protect the motor.
Mount
Transom brackets are available in strong nylon or aluminium. We recommend nylon for most purposes, it is very strong and light and does not corrode. The aluminium is normally used where the extra strength is essential and or wide temperature variations are encountered.
Propeller
The polycarbonate propeller is very strong and is designed to push weeds aside so allowing access to weedy and shallow waters
Thrust & Power
All electric trolling motors have their output expressed in lbs thrust, where as outboards are normally expressed in terms of the horsepower they can develop. The former is a measure of power, the latter a measure of work and thus there is not a direct conversion between the two units.
However as a practical guide using:
Power = Force X Velocity.
As a straight conversion to eliminate the constants of the various units used,
the following formula applies -
Pa = Ta V / 325, where -
Pa = Propulsive Power available in Horse Power, Ta = Thrust available in
Pounds, and V = Velocity in Knots.
So for a 66 lbs Thrust motor travelling at 5 knots the equivalent in Horsepower is approximately 1 HP
This does not fully take into account propeller and motor efficiency and in practice a 66lbs electric motor is generally equivalent to a 2-3HP petrol outboard, but there is no direct comparison.
Certification
All our Trolling motors conform to the Electromagnetic Compatibility Directive 2004/108/EC. Copy certificate available on request.
We recommend a deep cycle marine battery to deliver the longest cruising range and for overall battery life. Deep cycle batteries are designed to be fully discharged and then re-charged, whereas car batteries are design for constant top up charging from a car's alternator. However they will run quite happily on a car battery and the LED display will give an indication of power left in the battery. Experience will tell you how many hours cruising this will give you. As an example a 30 lbs motor draws 35A at full speed, so a 70 AHr battery will give you about 1 1/2 hours running at full speed allowing for losses and not totally discharging the battery. In practice you will not be going at full speed all the time so may be able to get 2-3 hours cruising
It is recommended to keep the battery in a battery box to protect it from water splashes, especially at sea.