I recently converted my 1973 Westerly Chieftain to 100% electric drive with solar recharging.
Motor is air cooled 3Kw 48v running through a 3 : 1 reduction pulley system.
Battery bank 1 is 48v 250AH
Battery bank 2 is 12v 400Ah
Charge system is 400w 12v of solar panels still to be fitted
A 2000kw 12v pure sine inverted which runs a 48v 15a 5 stage smart charger.
So far I have 5 hrs running time with little to no drain on the batteries. At 4kts the motor draws between 12 and 15 amps which gives approx 10 to 15 run time.