FIX BALLAST TANK

Q:

Hi Doc. We just bought a 2018 Malibu, and the ballast tank is leaking. Can this be fixed?

Jan McNeil St. Louis

A:

You’ll have to determine the source of the leak. Two common failure points in watersports boats’ ballast systems are the hose-barb-fitting nipple on the tank and the vented loop. To repair the former, remove the old cracked one and replace with a PVC fitting of the same size, sourced from a plumbing supply store. If the tank fittings screw in, this is relatively easy. If they are molded or welded plastic fittings, you could drill it out and replace with a flanged through-hull fitting of the right size. You’d probably need to cut an access panel to tighten the nut of the new fitting—cut this in the top of the tank, then close it off by installing a screw-in deck plate. Seal everything with a good sealant such as Pettit AnchorTech Advanced Hybrid Sealant, which remains flexible. Adhesion is not necessary because not much will stick to poly tanks.

Or replace the tank with a new one or a bag.

The vented loop is a horseshoe-shaped fitting that prevents water in the tank from siphoning out. It has a valve—called a duckbill valve—inside a screw-off cap located at the bend in the U. Remove the cap, then clean the valve of any gunk. You can also purchase a new valve or a new vented loop from Forespar and others.

This will typically be mounted high, so just follow your hoses. You will want to follow all hose runs from the tank to the fill/drain pump(s) and to the discharge fittings on the hull. Your leak could be in any hose or fitting, or the pump connection, though I believe the two examples are the most likely.

Access is going to be the toughest part of this DIY task.