That's true, however that's not the path they are trying to go down. If unabridged unanimous responsibility of the boat was placed solely on the skipper, and he was within the .08 limit, then the sailboat would be immune to any legal actions against it, especially concerning a collision with a power boat.

Instead, they say the helm was BUI. With BUI all that really matters is the person operating/driving the boat was over the legal limit; the responsibility of the skipper/owner of the boat is not a factor in the black and white definition of BUI. So they charge the helm with BUI, and since a death occurred while BUI..manslaughter.

The argument will be between whether they can charge the helm solely on the black and white basis of the BUI->manslaughter, or whether they will be forced to consider other factors such as the role of the maritime responsibility of the skipper. it's purely interpretation.