Most wake shops caan get or have bags of lead available. If your in so cal. PoP Products bags are the best. Cant be shipped due to the weight involved though
You can go to a gun shop. And ask about lead shot for reloading. You can get it in a nice burlap bag and since it is shot and not a brick you will do less damage to your boat. Only carch is they will want you to pay for it.