On Sun, 28 Jun 2009 17:04:34 +0000, Larry wrote:

Unfortunate equations:

Runtime (R) = Amphours (AH)/Thrust (T) squared

...so plan on the dingy being a DISPLACEMENT hull on battery power.

Also, unfortunately, AH = Battery Weight (W)/50


Larry, what are you thinking?

You're equation for a 19 lb thrust trolling motor and a small 23 AH
"utility" size batter gives a run time of 3.822 MINUTES.

That setup gives me about 3 hours running time. Admittedly 19 lbs
thrust is not enough for an inflatable. However I did have an 8 1/2 ft
inflatable with a 35 lb thrust trolling motor (might have been 30) and
type 24 battery. I got about 4 hours run time with that and it pushed
the inflatble about 4.5 kts according to the GPS. 4.9 Minutes run time
according to your equation.

I'm assuming your equation is Runtime in hours = Amphours / Thrust in
pounds squared?

So Richard, if you're not in a hurry, pick up a 30 to 40 lbs thrust
trolling motor (you don't have to run it full power) and a type 24
deep cycle batter. A type 27 will give longer run time, but the 24 is
fairly light.

Rick