My thoughts on getting an electric boat motor: Hell NO!
A) Cost is ridiculous and I doubt it will come down quickly, too much demand for the rare earth metals for use in electric cars, bikes, scooters, laptops, phones and tools etc, and it's increasing.
B) Safety - lithium batteries, electronics and water, (especially salt water) sounds like a fire waiting to happen. Okay maybe not a huge individual likely hood but there seems to be a significant fire problems with charging bikes, scooters, not to mention cars; Porsche, Audi, Jag, and Chevy Bolts all have issues. There is a reason lithium batteries are treated as hazardous material for shipping purposes.
C) Range - Its hard to beat being able to pour more gas into the tank to go further. Out of state camping, staying at a hotel or even a friends house, charging could be an issue. Gas stations are located pretty much everywhere, and if not bring an extra gas can with you. Okay gas isn't the safest material either but its one we're used to.
D) Longevity - The average age of my multiple outboards is roughly 20 years, and running strong. I've got gas engines dating back to the 70s that run, or at least could be gotten running with a little maintenance that's in my ability to perform. How many years is this electric tech going last around the high moisture marine boating environment? (note: I admit I'm driving around in mom's 2004 Prius, getting it for free with less than 35K miles is hard to turn down and it gets roughly 3X the mileage as my rock crawling tricked out Xterra. The amazing thing is that the Prius' motor battery pack is original at almost 20 years. Way over the original predictions, so who knows what the battery life is, if not abused.)
KISS (Keep It Simple S....)