My Sacs are Bulging

[ragboy]

The reason for the c/v in the vent, and requiring pressure was needed, because I DO need those suckers full. I need all the weight. I am working on another method to help reduce bulge, but don't want to post yet, but you can contact me via email.

I didn't know about c/v that didn't require any pressure, and that is great, because that makes me want to try replumbing again to vent out the side. Where do I get those?

As far as the steel plates, I think that works well, but it works if you only do one side. The whole point of this is to not be moving weight around manually, and it negates the effect if I have to keep 250lbs or so on each side. My wake is def best with NO weight on opposite side. But it is a great idea. Where do you get those elevator plates anyway?

Anyway, would love to get a hold of some of those free flow check valves.

[chpthril]

The reason for the c/v in the vent, and requiring pressure was needed, because I DO need those suckers full. I need all the weight. I am working on another method to help reduce bulge, but don't want to post yet, but you can contact me via email.

I didn't know about c/v that didn't require any pressure, and that is great, because that makes me want to try replumbing again to vent out the side. Where do I get those?

As far as the steel plates, I think that works well, but it works if you only do one side. The whole point of this is to not be moving weight around manually, and it negates the effect if I have to keep 250lbs or so on each side. My wake is def best with NO weight on opposite side. But it is a great idea. Where do you get those elevator plates anyway?

Anyway, would love to get a hold of some of those free flow check valves.

www.plumbingsupply.com has them, they are swing-door flapper style.

[ragboy]

Thanks, this may help me feel better about routing out the side with the T in the plumbing. I ordered 4.

[Greg Mallek]

I may have some of those weights in my werehouse. I'll check. The have a built in handle as well for easy(er) carrying. I'll get back to you.
The accual dementions are: 1"x8"x16".

[Fast1911]

Bulging Sacs..................

[talltigeguy]

This is not the answer you want to hear, but hear goes, FWIW. I never had any of these problems with my custom sac in my Tige and it was basically a pre-Enzo surf sac (they did not make it when I ordered mine). When your sack is full, it is not really full if I understand correctly, and that is why you get the sloshing and lifting of the seat.

If the sac were really full, there could be no sloshing around. But you can't fill it 100% full because it would explode the boat.

Your sacks seem like they are too big.

I was jut on my Buddy's 247 yesterday with an Enzo sac and was bumped up into the air a little when he came off plane, so I just saw exactly what you are experiencing. He chooses to not fill the sack full, for reasons I don't quite understand. If the sack is tight, it should be impossible to do that, right?

So I think a sack that is perfectly tight, but not threatening to break the compartment is the solution. In theory you would have just about the same amount of weight, the bag would just bulge until it fills the compartment, and the stress would be on the bag, not the boat. It would take precise measurements, and I guess I got lucky when I did my custom sack. What do you think?

[ragboy]

The sac is tight, its filled to the brim. My pump wouldn't have any more pressure to fill it up more. That is why I have the spring type check valve in the vent to keep pressure, and keep from leaking. The issue is, I need to make things fit better, and have a 3 tiered sac, not 2. I have a solution, testing outside my boat now.

[ragboy]

I could solve the problem very easily. Do what Greg said and add a weight or some lead. But then I have to move that from side to side. I am done doing that. Or, don't fill them so much, but I need that weight.

Do you guys know what it is like, when you have guests on your boat, so you end up surfing 2x as long, to give everyone a ride, and have to switch from side to side? This is my life, I do this every time we go out. My family is just big, I love it, but it makes some things more challenging.

We go 3x a week (tue-thurs), on the lake between 4-4:30 pm, because usually the wind dies down around this time, and there is always smooth water to find midweek like this. We fill the reg side as we 5mph out of the marina. We drop in ashley just outside the marker and she surfs out. She rides for a good 20 mins. Then we stop, and switch sides, about 15 mins cuz we are not in a hurry. Everybody swims and cools off. Sometimes I do a quick video or something on the back of the boat. Then we start the goofy riding. Sometimes we give Jess 20 mins first, so she can try standing. She tries every time we go out, she is gonna do it. Then 4 other kids, and my wife is learning. That takes us to the point, where I have the lights on when I am idling in the marina, and just barely light as we put the boat on the lift, and walk up. It is usually dark by the time we are pulling out of the marina.

4 hours of solid surfing with a swim break while we switch sides. That is it man, there is just a lot of us.

[ragboy]

too funny. I ordered these valves yesterday, just got them. I ordered ground, WTF? I look, they are in chico, like 20 mins from me.

[talltigeguy]

The sac is tight, its filled to the brim. My pump wouldn't have any more pressure to fill it up more. That is why I have the spring type check valve in the vent to keep pressure, and keep from leaking. The issue is, I need to make things fit better, and have a 3 tiered sac, not 2. I have a solution, testing outside my boat now.

And when you let off throttle, the water rolls up the side of the boat, and pushes you up out of your seat.

I thought it would be impossible for the sac to bump the seat up when you slowed down if you truly had the sac all the way full.

So the tongue of the sac becomes 'more full' when you let off the throttle so that it bumps the seat up?

Imagine the sacs in the picture with RJ at the first post, there is going to be no bump in the tongue when you jump on the taller portion because it is already maximally full.

I am not trying to argue, but can't help but think a full sac cannot slosh and push you up out of your seat. Just trying to understand better. Maybe there is enough air in the sac to cause it and another air vent needs to be placed?

I love seeing your writeups and hope to see more coming. You have helped enlighten a lot of us.

[Duncan]

I thought it would be impossible for the sac to bump the seat up when you slowed down if you truly had the sac all the way full.

I think you are assuming the sack cannot further expand past its "full" size. De-acceleration causes the water in my sacks to surge forward, bulging an already expanded foot extension portion of the sack, in turn causing upward pressure on the seat.

If the container was rigid and completely full, then there would be no surge, only a mass effect on the front portion of the container--so long as the structure remained intact, there would be no bulge. But such is not the case with the pliable sack material.

[ragboy]

Thanks. You can look at the video when I open the locker. That sac is filled, no wrinkles, tight. Its just like a water bed, even full, you put more weight on one side, the other is going to move, unless you filled with so much pressure, which would probably be enough to pop the fiberglass.

The solution we are working on, is to create a 3 tiered sac by having one custom sac, in L shape in rear, and then one other in front of it along side. Using our knowledge of bulging, to better measure what we need, to get max weight, with less damage to boat. The issue is the ways to connect the 2 sacs, so they still fill as a unit and empty properly. We are testing, and almost there. This also resolves the water moving forward, since they are only connected, there is some movement, but not much. Filling is easy, emptying is more of a challenge, but we are getting there.

[dogbert]

I am not trying to argue, but can't help but think a full sac cannot slosh and push you up out of your seat. Just trying to understand better. Maybe there is enough air in the sac to cause it and another air vent needs to be placed?

Au contraire. My bow sac pushes up my front seats when full and I plenty of vent. There's very little air in there. The problem is that the Ballast Puppy pumps pressurize the system a lot more than the aerator style pumps, even with extra vents. It's a lot of pressure in an area that perhaps was not designed to withstand that amount of force. It's analogous to bicycle tires. Each is rated to a certain PSI. If you exceed the PSI, the tire will explode. Tubes, on the other hand, are not rated to any PSI level. They'll just expand to fit and put pressure on whatever you're putting them in.

In this case, the boat is the tire and if it's not designed to handle pressure in all the places you will put on it, then you will have problems. Obviously, air does not weigh much, but water does. As a result, you have the additional laws of motion to deal with.

[Duncan]

For an '09 RZ2 and the 22Ve/RZ2 custom sack, the only spot I am worried about (so far) is the firewall between the locker and the engine. The sacks have moved the bottom edge of the wall in toward the engine.

My solution will, presumably, be to reinforce where the bottom edge of the wall interfaces with the deck. Right now there is nothing there.

I am also a little worried about the cup holders popping up but I plan to use Dogbert offered solution (post #5) of plastic drinking cups underneath.

[talltigeguy]

Au contraire. My bow sac pushes up my front seats when full and I plenty of vent. There's very little air in there. The problem is that the Ballast Puppy pumps pressurize the system a lot more than the aerator style pumps, even with extra vents. It's a lot of pressure in an area that perhaps was not designed to withstand that amount of force. It's analogous to bicycle tires. Each is rated to a certain PSI. If you exceed the PSI, the tire will explode. Tubes, on the other hand, are not rated to any PSI level. They'll just expand to fit and put pressure on whatever you're putting them in.

In this case, the boat is the tire and if it's not designed to handle pressure in all the places you will put on it, then you will have problems. Obviously, air does not weigh much, but water does. As a result, you have the additional laws of motion to deal with.

So your sack is also too big.

The actual measurements should have been a little smaller than your compartment so that you do not bulge up the seats. You would have the same volume of water with a smaller bag (unless you currently run with the seats bulging up).

The bicycle inner tube analogy is not anything like this. These sacks are rigid when full and do not get any bigger. Nor can they continue to withstand increasing volumes of water in them. Once they have reached their full size (which is bigger than the measured size when ordered from the factory, as Ragboy has eloquently pointed out), they will not get any bigger, period. No matter how much pressure you put in them. The vent might spew higher, or it will eventually blow out. Ragboy's sack wants to get bigger and it is threatening to break his boat to do it.

Your PSI analogy is exactly the problem here. Ragboy is worried about the PSI in his bag because it is about to rupture his boat. I would make the bag small enough that if there were too much PSI in the bag, the bag then ruptures, not the boat. I think it is a fine line in trying to maximize the space, but is what needs to be done if he is going to resolve the issue. If the bag is too small, he loses ballast, if it is too big, the boat cracks before the bag reaches its full size.

I think it no coincidence that I never had this problem with my custom surf sack because I ordered it slightly smaller than the compartment, to allow for the sack's shape change when full, and it did not put much pressure on the walls of the boat when full. But there was definitely not space to spare.