I recently bought one of the Fly High U-shaped bow sacks and put it under the bow cushions. Since the wind was blowing and I couldn't get on the water I thought I would check to see how much water weight I could get in there. I have a scale about a 1/2 mile from home so I filled the sack weighed my boat..emptied the sack weighed my boat and I got 220lbs under the cushion of my 04 VLX. There was a little air in the sack, but I would guess the MOST you could get in there is about 250 on a good day. I've seen a lot of weight numbers posted here and there that were estimates, so here are some numbers from a certified scale. Maybe I had too much time on my hands today