I don't quite understand how and why these are constructed as they are, and maybe there's an engineer here who can explain, but this article describes the pontoons as being partially full of water by design. So when the boat slows, weight rushes to the bow. Seems incredibly f'ed up to me, and easy to understand how a captain could make a fatal error
https://www.bangordailynews.com/2025...oo-joam40zk0w/