Estimate the wattaage, e.g., the amperage for a given voltatge, 12 volts in my case

[Jerry_NJ]

Is there a table or similar showing a typical watts per pound of thrust for a mid-priced (Min Kota, say) 12 Volt trolling motor? This would be helpful in deciding how many amp-hours the power source battery needs for a desired trolling time. In my case, not done in a few years and don't recall, I'd likely use a 30 pound Min Kota in the 10-12 pound thrust range for two to three hours.

 

[Silvertip]

You plan to run a 30# thrust motor that under worst case conditions will draw about 38 amps @ 12 Volts. There is no way to accurately determine what current draw will be at 1/4, 1/2 or 3/4 speed setting because of the variables such as load, water conditions, type of boat, etc. What you do need however as a minimum is a group size 24 deep cycle battery. And when you shop for that battery, pay attention to the label -- specifically the RESERVE CAPACITY which will be expressed in MINUTES @ xx current draw. That XX number is usually in the 25A range. So a battery that is labeled as 150 minutes @ 25A could run a 25A load for 150 minutes. In your case you intend to run the motor at less than full speed so run time will be longer because the current draw will be less. How much less is unknown and a guess at best since we have no other details.