Quick description of what each do: Both check valves and vented loops are used to prevent the passive draining of bags (draining while pump is off and boat is in use). However, only a vented loop will also prevent the passive filling of a bag (think opposite of passive draining).

Vented Loops:

If your ballast bag is going to reside below the floor/below lake level (think ski locker) Then you’re going to need to integrate a vented loop in the ballast hose line in order to prevent both the passive draining and filling of the ballast bag. The reason is that vented loops are fitted with a one-way valve right at the high point in the loop. This valve still allows water to be pumped through the loop like a solid tube, however, once the pump is turned off air is let in through the valve and into the tube. This allows the water to drop on both sides of the high point in the loop and prevents a siphon from occurring. Now, for this to all work correctly you need to install the vented loop as high above the water line as possible. The most common location for installation is under the driver’s dash near the windshield. If you’re installing it in the back of the boat, whether in a direct drive or v-drive, up under the gunnel is usually the best location. It’s also important to install the loop as close to the ballast bag in question as possible.

Check Valves:

Now if your bags are filled above the water line then check valves will work great as you won’t have to worry about passive filling. The check valves will take care of any passive draining and you’ll be on your way. Plus, check valves will cost you less and are easier to install. Check valves are basically just a non-return valve that requires no maintenance, will never rust and can be installed in any position and at any angle. When building a ballast system there are many applications for non-return check valves. Because of this we have done extensive tests to ensure the valves that we offer will perform in pretty much any situation you can conger up. And while it might sound like a plug for our product, we really don’t recommend using valves designed for use in a domestic plumbing environment (meaning both the swing valves and spring-loaded check valves you would find at the hardware store). The reasons for this are:

1. They are installation attitude dependent; because they rely on gravity to close the swing gate, they must be installed within a range of angles, which is less than convenient when running lines for ballast.
2. They’re bulky, and typically require additional fittings to convert the threaded connections to hose barbs, which increases the size even more and adds more failure points.
3. And, they’re expensive (compared to the integrated hose barb valves we offer).

One thing to keep in mind when building your ballast system; If you choose to forego the use of check valves, your system will essentially remain incomplete. You’ll never be able to fully drain your sacks completely without them. Meaning unless you have a check valve to prevent air from flowing back into the bag, you’re bags will never be able to raisin up and stay completely drained.

Hopefully this has instilled some knowledge in the heads of all who read it. If you have questions feel free to contact us and ask away. We’re always around and ready to help you build the perfect ballast system for your boat.

Whether you’re designing a new ballast system, or trying to upgrade your existing system to fill and drain faster, one common question is how best to design the system so it is as uncomplicated (and also inexpensive) as possible.  One of the tools that we use when helping people design a custom ballast system is a product called a vented loop.

As shown above, a vented loop is a “U” shaped plastic fitting that is installed in series with the fill pump when using aerator pumps.  During filling, the vented loop is invisible, functioning as a section of hose without any limitations.  The beauty of the vented loop only comes into play when the the fill pump is turned off, which means there are no drawbacks to implementing its use.  When water is not being forced through the fill hose, air (but not water) is allowed to pass through a vent at the top of the loop, which allows the column of water from the vented loop to the fill pump to drain down to the level of the pump.  

It is this column of air (typically at least two feet long) that prevents water from siphoning into, or out of the ballast bag when the pump is not running.  Many people are under the impression that water is forced past the fill pump due to the boat running at speed, but it’s not possible to develop that much pressure, and it actually just the siphoning process that allows the bag to fill or drain.  The vented loop solves that problem by creating a break in the column of water running from the pump to the bag, so siphoning is not possible.

To function correctly, the vented loop needs to be installed close to the ballast bag in question, and as high above the water line as possible.  For forward ballast bags, the typical installation location is under the driver’s dash up near the windshield.  In the back of the boat, up under the gunnel, whether in direct drive or v-drive boats, is typically the best location.

If you have any other questions about the vented loop in particular, or ballast systems in general, please feel free to contact us.