Coming off of the top of the main part of the sac is a vent/overflow line. This line is used to vent any air out of the top of the sac so that it can fill completely with water. It is also used as a pressure overflow in case you leave you pumps running too long and risk bursting the sac.
I used quick connects for this line as well. The vent line hose comes out of the sac and goes into a one way valve and then to the side through hull. The one way valve stops any water from coming in from the side through hull into the sac. It also allows the sac to raisin up and lay completely flat in the bottom of the locker when empty.
I initially put on a flapper style check valve but the surging of the boat when we would start and stop would push water out of the vent/overflow. So I switched to a spring style check valve which worked better but I still would lose some water. So ultimately I put a manual check valve in line. I open it to burp the air out of the sac... other wise it is closed. I have to watch the sac to make sure I do not overfill it because there is no emergency overflow now.
Since my install many people have started to run the vent/overflow line to the opposite side of the boat. This allows the check valve and side through hull to be much higher than the overflow on the sac (because of the leaning of the boat). Because of this lean the water does not flow out of the side through hull. With this design you can utilize a flapper or spring check valve only and it functions as it is designed. If building another ballast system I would definitely use this modification.
Here is a picture of the top of the sac. You can see the quick connect in the middle of the sac for the vent/overflow line. You can also see how well the sac raisins up when it the water gets sucked out of the sac.
Here is a picture of the one way check valve and then you can also see the 90 deg angle and then the side through hull.
No comments:
Post a Comment