I also have both a 400 watt-hr battery and a 520 watt-hr battery and got pretty much the same results that Max did pushing my compact rib 310. I am building a 10' hard dinghy now and will report on how well the Torqeedo does with that dinghy later in the spring. As far as security for the motor goes, I don't leave it on the motor at the dinghy dock overnight. I take the motor home and recharge it. It is a bit of a nuisance, but my motor stil looks brand new after two seasons of use. I know it would be rather beat up if I had left it on the dinghy at the dock for those two seasons