another IBS install question.

[996scott]

OK, I want to make sure I have this right so sorry this is probably a repeat question. I have done a lot of reading so tell me if I have this correct. I want to add the IBS to my 07 LSV without drilling holes and adding new pumps and the whole 9 yds. I just want to fill and drain it through the ski locker ballast bag. So I will add a line to the front (closest to the bow) of the ski locker bag and run that line to the starboard side of the IBS. So once the ski locker bag is full it will then push water into and fill the IBS. So this is where I am not quite sure...I then add a vent line to the IBS that will "T" into the existing drain/vent line that comes from the ski locker bag and goes out the side of the boat? and I also need to add a check valve to that same drain/vent line right before it goes out the boat? What is the difference between a spring loaded check valve and just a check valve? Which one do I need? I have also read about putting in a 3 way valve but since I always plan on filling the IBS along with the ski locker bag then I don't need this right? Sorry for the hand drawn picture but this is how I have it in my mind..

[rbeckner27]

If you have a bag and not a hard tank in the center of the boat then you do not need a spring loaded check valve, just a standard check valve as wakemakers sells. also if you plan to always fill the belly bag and ibs you do not need a 3 way valve as this is to give you the option to not fill the ibs.
Once again if you are happy always filling both bags, just vent the belly bag into the ibs and then vent the ibs in your thru hull that was for the belly bag and put your check valve in the ibs vent hose. this will all allow for your ibs to drain and then your belly bag to drain and all be drained flat with the use of the check valve.
Also i would pull the ibs vent line off the highest point in order get maximum fill.

[brain_rinse]

Your check valve needs to be closer to the IBS before it ties into the drain. Otherwise it will just drain the ski locker bag into the IBS. Otherwise good to go.

[996scott]

ok, thanks guys. So the check valve will be between the IBS and where it ties into the drain line, not between the tie in and the where it goes through the hull, correct?

[brain_rinse]

Yes Correct

[jstenger]

Do you have reversable pumps? Looking at your pic, it doesn't look like it.

[996scott]

no, it is the standard gravity III set up. I have only replaced the rear bags with 750s.

[jstenger]

OK, here is my take on this.

1. Since the original center bag wasn't vented, I would not vent the IBS. Just use the air release plug that comes with the bag.

2. Since you are using an aerator pump, you may have trouble filling the IBS completely from the center bag vent. In my experiance with piggy backing bags with an aerator pump, I have found that the water will actually go thru the drain pump and out the side of the boat before the IBS fills completely. This is mainly caused by the 3/4" fittings that restrict flow between the center bag and IBS, which is more than the restriction of the drain pump's hose. You may need to add a simple plastic 3/4" ball valve to the drain hose which would have to be closed when filling and open when draining.

3. Make sure the fill line for the IBS is on the bottom right port.

[gregski]

1. Since the original center bag wasn't vented, I would not vent the IBS. Just use the air release plug that comes with the bag.
In the stock GIII setup, the center bag is vented through the drain pump in exactly the same manner as the rear locker bags.

[jstenger]

In the stock GIII setup, the center bag is vented through the drain pump in exactly the same manner as the rear locker bags.
I respectfully disagree. The pump is below the water line. Therefore no air can get out. Thus, it is not a vent.

[gregski]

I respectfully disagree. The pump is below the water line. Therefore no air can get out. Thus, it is not a vent.
Hmmm, that is true. But the rear bags were set up the same way. Did the design assume that no air ever got into the system?

[jstenger]

Hmmm, that is true. But the rear bags were set up the same way. Did the design assume that no air ever got into the system?
The factory Gravity III ballast system installed in Moomba boats from 2002-2008 did not include a vent connection. You had to loosen the top plug to burp the air out of the bag. Wakemakers sells a vent upgrade kit for these years.

http://www.wakemakers.com/supra-moomba-vent-upgrade-kit.html