AIRE offers two different self-bailing floor options on their rafts. The Standard floor pocket, and the Sealed floor pocket.
The Standard has the zipper along the edge of the floor, near the self-bailing lashing, and features drainage holes on the bottom. These drain holes allow river water to enter the floor while floating down the river, and therefore add extra weight to the floor, which should provide some extra ballast, and help keep the raft from flipping over in the rapids. The down-side is that the raft needs to sit on the shore for a while, and drain out this extra ballast water, before packing it up after the trip. And if you float silty rivers often, the fine silt may begin to accumulate inside the floor, and eventually cause abrasion issues between the internal urethane air bladder and the PVC outter shell of the floor.
The Sealed floor pocket is just that, a sealed floor. The zipper is waterproof, and located in the middle of the upper side of the floor, to allow access for repairs, etc. No water gets inside the floor, so NO ballasting effect. But also, No silt can enter to cause damage over time. The Sealed floor also cost a few hundred $$$ more.
So, which option is best for Alaskan rafting???