Is the EA system powerful enough?
Our motor is rated for 3.3 hp (2500 watts) continuous. Others offer more powerful motors, but we think this is catering to unrealistic expectations from customers who do not understand the limitations of battery power.
The motor we use is also available to us in a twice more powerful version that is cooled by blowing air through the motor interior - and the price is the same. We prefer the less powerful totally enclosed version because it is more suited to the marine environment.
If you understand the simple math of battery power and the physics of moving a displacement hull, you will understand that a more powerful motor has no practical advantage.
The attached graph shows the actual experience on my 29' sloop Teal. The vertical scale is speed in knots, the horizontal scale is power in kilowatts.
Boats will vary, of course, but the difference will not be enormous. A longer waterline will help somewhat - Teal's is 20’. A big three bladed prop will also improve performance under power, but at the cost of significantly increased drag under sail. For people interested primarily in sailing, not motoring, this is a poor trade-off.
When we do motor in Teal, we never run at more than 1500 watts (2 hp), and usually run at 500 watts (2/3 hp) or less. More power is wasted on a very small increase in speed, and at a cost of rapid battery depletion.
The advantage of lower speeds is even greater than the graph shows, because the amp/hour capacity of batteries is greatly reduced at higher rates of discharge, and battery lifespan is decreased as well.


graph 3
Teal: speed in knots vs power in kilowatts