First modification – auto-venting ballast tank

The first modification I made to Southern Star was to upgrade her ballast tank.  A MacGregor 26M has a tank under her cabin floor that can hold 1200 lbs of water to provide her with some stability and counter-weight to stand her upright when the wind tries to heel her over.  The tank as it comes from the factory has two valves that have to be opened.  One at the stern that I can reach with a boat hook easily enough, and one down in the cabin up under the forward berth.  What a pain that one is to get to and use.  Especially if you prefer to motor with her tank empty for better speed.  You can’t (and mustn’t try to) sail her with an empty tank – it’d be dangerous.  So I found myself looking for a way to make this easier.  What I chose to do was to replace the valve under the forward berth with a pipe that vents overboard.  I took the valve out and in its place inserted a brass threaded fitting that had hose barbs.  Lots of 3M 5200 marine sealant, of course.  I routed the hose from the vent up under the berth to the nose of the boat and up to the anchor locker.  I installed a thru hull fitting there at the top edge of the locker and clamped the hose down there.

Now when I open the valve in the stern, the water can flow in easily, and if I motor over about 7 kts it flows out just as easily.  When I have her either full or empty for the needs of the travel segment at hand I close the valve and I’m all set.

Someday I’d like to add some type of water level sensor to the tank that would toggle a light on the steering pedestal to let me know if it wasn’t completely full or completely empty to give me that better warm fuzzy that my boat is configured safely for the type of boating I’m currently engaged in.

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Categories: Modifications | Tags: , , | 4 Comments

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4 thoughts on “First modification – auto-venting ballast tank

  1. Dad

    Wow! You’re making modifications already. There are sensors for monitoring tank level. The best ones are ultra sonic. No moving parts. It just mounts on top of the tank. It sends a signal down and it bounces off the water surface and back to the receiver, converting the time down and back to inches H2O.

  2. A possible future upgrade! Thanks for the tip!

  3. Tuan

    So the vent is always OPEN, right? Also how do you know when the tank is full? Many thanks for your response in advance.

    • Yes, the front vent is always open. When I’m motoring, I leave the back one open too. That way if I run fast, it empties the way I’d need to run at speed, and it fills up again when I slow down or stop. If I sail, the back is left open until we raise the sail and unfurl the jib. By then it’s plenty full, and I close the vent and sail away. I do want to add a sensor someday, along with one for my freshwater tank and my waste tank.

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