2-4 elec. 30-36lb thr, what can it move?

746 watts is one HP. The obvious conversion is to find the draw of the motor and using Ohm's law convert to watts. The problem is the math is only good in the first few minutes of operation on a battery powered setup.

The basic problem is thrust is a force or pressure, typically measured in pounds or newtons, while horse power is a measure of work over time or more directly; HP = the motion a force creates, when it is exerted on a body over a certain amount of time

So lets take the largest Minn Kota 12VDC motor, which is rated at 55 pounds of thrust. The max motor draw is 50 amps, so multiplied by it's voltage you get 600, which works out to be .8 HP.

Motor draw (amperage) is usually printed on the label. You need a 62 amp motor to have one HP. Currently no 12 VDC trolling motors offer this, though 24 and 36 VDC motors do offer this and more.

Generally, the biggest commonly available are the 110 pounds of thrust 36 VDC models, which are about 1 3/4 HP. These usually cost about as much as a 2 HP outboard, but counting batteries, weigh considerably more. There is a 160 pounds of thrust setup, designed for anti-ventilation plate mount, but it's really just two 80 pounds of thrust motors.

In reality, counting speed drop off as the batteries wear down, the real conversion is more like 900 watts per HP, once everything is said and done. This means the 55 pounds of thrust, 12 VDC trolling motor is really a .66 HP tool, by the time it gets you back to the launch ramp, at time reduced output. At least this has been my general findings. So, if you gear your power requirements at 75 pounds of thrust for 1 HP, you'll more accurately represent the true nature of electric propulsion with a trolling motor setup.

 

Eric; Have you considered a sculling oar or perhaps a yuloh? Preserving the tranquility of a quiet night is worth some exploratory experimentation.. A 5 or 6 meter oar will propel the boat quietly and happily. A yuloh is more powerful. The chinese propel large boats great distances with the crooked oar device. Both of those items are simple, durable, effective, quiet, and cheap.