Look up "hull speed". You might find that 2Kt is about the top end that a 5 foot boat can economically manage. According to the calculator on
https://www.easycalculation.com/phys...calculator.php about just under 3, but this will drop dramatically with anything other than a nice smooth, clean hull.
Duration will depend on the size of the battery that can be carried. Anything being dragged will act as a sea anchor and reduce performance
If intending to be actually seafaring, have a look at
SEACHARGER - SeaCharger Oceangoing Autonomous Boat - Home where you might get sime useful tips from somebody who sent a boat from California to Hawaii, and almost got to New Zealand.