Electric motors are used by the thinner members of my fishing club (the rest of us row to get a good workout). They are effective in calm conditions but need to be supplemented by oar power to make headway against a gale (known here in Ireland as a “good fishing breeze”).
The main problem is the weight of the batteries. You need too heavy duty leisure batteries for a day’s fishing. For advice turn to your local tackle shop – electric motors are used by anglers.