Piggyback sack going to burst....

[StrmChzr]

After a few months of owning my 05 XStar, I ordered a #1100 sack with piggyback apparatus to improve surf wake. The result was a kick *** port wake as well as a streamlined and efficient fill/empty system. My total fill time for port stock tank and #1100 sack is 12.5 minutes and I don't have to dink with manual pumping.

The only problem with set up is that the #1100 sack doesn't vent despite being properly installed. It would be great to flip a switch for filling ballast while boating to surf spot. Instead, its a pretty big buzz kill to have to leave rear locker open to keep an eye on pressure building in sack and not be able to let it run "automatically".

I contacted Jason at WM'ers to assist with troubleshooting. He gave me some good advise for my system in hopes of fixing the vent problem.
1. Turn sack around in locker so bag fills from locker's front side (towards bow) instead of from the transom.
2. Replace vent hose straight fitting with 90* fitting on top of sack, so vent hose doesn't pinch when sack is full and locker is closed.
3. Confirm vent hose is free of obstruction by blowing through it.
4. Secure vent hose to boat so that it gently angles up towards the vent on outside of boat.

So I did all these things this weekend, but sack still didn't vent without me opening the 3rd valve on sack manually. What am I missing here? I'm somewhat dumbfounded that Jab pump can create enough pressure in sack to raise concerns with rupturing but not being able to vent thru 4' of unobstructed hose........

[MLA]

Yes, a reversible impeller pump can produce enough water pressure in the sac to rupture something.

When the sac is full or near full, is your current vent hose on the highest of the two top sac ports? This helps to vent the air, but even if its on the lower port, is should still allow excess pressure to be relieved from the sac. How much pressure is it actually building?

How is the vent line routed? If it takes and dips, it will hold water in those low spots, which makes venting tougher.

[Jerseydave]

How did you fit that sac in your star? Assuming you have it on the port side, I also assume you relocated your batteries?

Fatsac makes a vented "cap" if you want a temporary fix.

[StrmChzr]

Top Vent port is closest to bottom fill/drain port on sack. It seems to be the higher of the two top ports, but I'll pay more attention next time out.

It's difficult to quantify how much pressure is building in sack. A few times the sack has been "drum tight" and literally bulging out of rear locker compartment w/o any air or H20 venting. The #1100 sack is slightly too big for rear compartment lid to close when completely full, so I haven't "forgotten" to turn off pump and risked rupturing sack - yet....

Jason also recommended I position vent hose in such a way as to prevent bends in hose that would create a "valley" in hose for water to collect and possibly impede venting process. I did disconnect the vent hose and blow water out of it. I then zip tied the hose in such a way that hose is as straight as possible leading to boat's Thru hull vent port which exits boat near the glovebox. When I tested out this possible fix, the results didn't change. I actually held a feather over thru hull port on outside of boat to double check there was no air movement while filling and draining.

I didn't move my two batteries from port side (yet) b/c it seemed their weight was beneficial in current location. I push them back a few inches so they take up most of the available space between port corner of couch locker and rear port locker. I'd be totally willing to reinstall them on starboard side if beneficial to resolve vent issue.