That makes more sense now. We can't link to the product - and probably shouldn't name - it here on the forums. But that makes things a little more clear.
All good - for a non-boater, you're up against a little bit of a struggle. You don't understand the community of users quite enough to define the market segments. If you'll notice, here on iBoats, there's not really even a lot of sailors - mostly power boat types. Why? The two segments approach things a little differently, and see things through different lenses. A guy who uses a 14' boat for fishing (with a 9HP on it) is using his outboard completely differently than a guy who's trolling Lake Huron in a 24' fishing boat (with a 9HP kicker motor).
The skepticism you're encountering comes (likely) from too much speculation with no production. Electric powered aircraft and electric powered boats are in a similar state of development - difficult to get over some VERY practical humps. Make sure that skepticism is part of your market research : adoption by consumers is going to have to deal with the skepticism and find a way to break through. Part of where Tesla beat that was a combination of performance - that bloomin' car MOVES

- and a commitment to infrastructure. Elon Musk has done a lot to build a supportive structure to make the car practical. The market isn't adopting it as a whole yet, but I am seeing them on the road here in the greater Nashville area, so it's starting to overcome the practical skepticism. But it's in no way competing in large part with gasoline cars, and stands a reasonable chance of "fizzling out."
Personally, I don't think noise is a major issue for most boaters. Sailors aren't gonna' turn the outboard on until they have to, and the rest of us likely most concerned about getting the most output from our drivelines with the least consumption of fuel. Time and distance ... The lake I'm on takes me about 30 minutes to go end to end at (about) 32MPH. That means a single charge in the motor you're talking about gets me there ... and almost home. If I can't make that kinda' headway, quiet is nice ... but not practical.
ALSO - remember the bulk of boaters (at least on this forum) are recreational boaters. Many of us are trying to enjoy the outdoors with our families ... BUT, it's all disposable income. We're going to try to do this as inexpensively as possible, and a large portion of us are running "well used" gear. Personally, the most expensive boat I've ever purchased was $500, and the most expensive I've ever owned was worth less than $10k when I purchased it. Others burn more money than that on their boats, but many are running boats that are capable of far more than a 13HP or 9HP motor would deliver.
Off the top of my head - the only market I could see quick adoption of such a thing would be if you had an outboard that weighed less than 30LBS, self contained battery and could deliver 3HP for a consistent 3 hours. You might get a fast adoption from guys camping with canoes ... they could motor up river and drift back down.
Though - now that I think of it - I believe there were some electric launches back in the early part of the century. Boats that would take people on shore from excursion ships; they didn't go fast but they had quite a few folks on board. Not sure if a 13HP would do the trick or not.
Outside of that, in my opinion, electric motors have some substantial hurdles to climb. Most electric only lakes aren't big enough to need more than a trolling type motor, most pontoons mask the noise of the outboard well enough as they already are ... plus sometimes mid-cruise, ya' wanna' get back home fast.
To be substantially competitive in the marketplace, an electric system is gonna' have to provide enough "oomph" to run a 20' boat with 8 people on board for a day of water skiing and tubing without a charge. It'll need to sit on the charger overnight, and then hit the water the next day to do it all over again.
It's a tough project to find the market ... You're gonna' earn this grade