View Full Version : Gravity III front bag vent

05-01-2014, 12:38 PM
I've been scouring all the previous posts on venting the front bag in my '07 LSV on a stock gravity III system. I cannot seem to find a way to do it without replacing the bag with a new one with a third port. I added a new 1,000 lb bag in the port locker for surfing, and it has the third port, which wakemakers makes a vent line for. I'd like to do something similar with the ski locker bag as it gets really full of air when filling. Ideas for a homemade mod?

05-01-2014, 01:02 PM
I replaced out the stock pump with a reversible pump then used the bottom bag fitting for fill and empty and the top bag fitting for the vent. There does not seam to be much air in the bag after i fill it. Now with that said you will have to redo the whole ballast system since with the stock ballast system there is one pump for fill and three sprinkler valves to control what bag gets filled.

The easiest would be to buy a new bag with three fittings.

Cigars n scotch
05-01-2014, 01:15 PM
I have the same problems on my 21V and I am exploring what to do to upgrade my system. 3 new reversible pumps with 3 new upgraded bags is what I guess I am looking at.

05-01-2014, 01:21 PM
I'd like to do the wakemakers full upgrade with dedicate reversible pumps, etc. but it runs ~$990. Thats a bit pricey for right now. If I rewired a new reversible pump into where the old one was and used the stock switch to control it, then used the top bag line for a vent, wouldn't that old sprinkler valve on the back just be "not used"? Or would it need power still to work correctly? Could I just remove the third valve and run two for the rear sacks?

Unfortunately I may just have to wait through this summer and buy the whole upgrade as a winter project as that seems the best way to go. It also replaces the scoop with three 1" flush pick ups and decreases fill/drain times significantly.

05-01-2014, 01:28 PM
You can cut your own vent. It's easy and there's directions on there somewhere on how to do it. Lemme look.

Edit: It's all here. I've done this to add a vent to a 2 hole bag.


05-01-2014, 03:33 PM
Kane, Thanks! This is exactly what I needed!!

Cigars n scotch
05-01-2014, 07:43 PM
Hmm I see that MLA was the one who originally did this. I am going to have to pick his brain. He just did my dual battery and perko and did a great job, we talked briefly about my want to upgrade my ballast sacs and pumps.

05-01-2014, 11:20 PM
I ordered the 90 through hulls. When the vent lines and those come in, I'll do a pictured write up of the install. Finishing up my hot water shower tomorrow!

05-02-2014, 09:46 AM
Kane, Thanks! This is exactly what I needed!!

Yea, don't thank me. It was MLA who showed us this could be done. More thanks to him again!

05-02-2014, 10:42 AM
OK, thanks MLA! But still you found the thread...gotta mean something.

05-02-2014, 11:37 AM
Another option is the Sumo 450 bag, it actually has better dimensions for the ski locker. Plus side is it has a handle on the top to help pull it out of the locker when you want to clean in there.

Also the Sumo bag material is more flexible and easier to fold up for storage.

I have been using Sumo Bags for 3 summers and never an issue at all.