Fly High Integrated Bow Ballast Fat Sac Fly High Pro X Series Integrated Bow Sac - This sac is designed to fit under the bow seats of virtually any open bow boat adding needed weight to the front of the boat. The sac will fill to fit the space allowed by the boat. If full this sac will add 1000 lbs. If you are adding weight to the back of the boat, do not forget to add some ballast to the front. If you put too much weight in the back you will have soft wakes, more diffuculty holding speed, and driveability issues. Balance is key!