Here is one way to look at it. A standard ballast sac will cost you about $.25 per lb of ballast capacity. A custom sac will cost about $.50 per lb of ballast capacity. Compare that to a fuel or water holding tank.
Sacs will fill up and conform to the locker cavity. A sac can be removed with easy. A sac only takes up space when its filled. A fuel tank will likely not have a side mounted port that would accommodate filling/draining. A water holding tank might. A fuel tank will have a large barbed filler inlet and very small ports designed for fuel return and venting. A water holding tank might have better port options.
Theres a reason there is a ballast sac market. KISS
Michael
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