This discusses the pontoons and the partyboat or "pleasure boat" as it's referred to in the article. They can be very stable, but they need to be pretty wide and as they saw in the video, you still want the boat to ride pretty low in relation to the size of pontoons you use.

A daggerboard is a type of centerboard that can be pulled up through a slot in the hull. Centerboards are mostly used in sailboats, but the reason they're needed is that in terms of forces acting a boat, sailing makes it top-heavy as fuck. This benchy is naturally top-heavy, so having a fin sticking down in to water helps, and having a weight on the end of it helps even more.

Ultimately, I imagine they ran across most of these concepts in preparing the video, but it wasn't as fun for their intended audience as a silly low-stakes 3D Printing YOLO meme, and TBF the 3D printing seems to have come off very well.

So I think the little bit they added is still there, but it just wasn't nearly enough. TBF, there's nothing inherently "wrong" with making a boat wider rather than deeper (e.g. the aforementioned partyboats), but as they saw it doesn't scale quite how you'd think, and much of the benefit they got from the pontoons that did work would have been there even if they'd left it flat.

Also, I guess the apparent half-assery is part of the appeal? I am not familiar with this Emily. I kind of assumed it was going to be an Emily Calandrelli video, but then I'm a dad who's watched a LOT of kids' Netflix.

Fiberglass may be overkill, but you would absolutely need some kind of sealing lacquer around the entire print or it will definitely fill with water.

You could also use a hydrophobic impregnator. Dichtol is a pretty good impregnator for 3d prints.