20" mono surface drive setup

[Chenige]

Looks like I am about ready to purchase the below for a 20" mono surface drive boat. Had one input (thanks Brydon) but was hoping for confirmation.

Turnigy Marine 35A Brushless Boat ESC
2 cell liPO Turnigy 5000mAh 2S 20C Lipo Pack
450 motor ADS300 Water-cooled Brushless Outrunner 3000kv 300w (revised)


What kind of run time will I get?

thanks