This boat hull was from about 10 years back when brushed motors were prime, and the hull is somewhat thin ABS. You can flex the V of the hull with a little bit of hand pressure. I wanted to lay carbon sheet inside, but someone gave me a better idea...

What I'm going to do instead is drill a hole in the top of the hull, use a funnel and pour a 2-part expanding foam mixture into the hull. The expanding foam is very strong when it cures. Then I am going to lay a small strip of carbon on top and re-drill motor mount holes. This will make it brushless worthy and strong without the flex.