I was thinking about adding some extra sacks on top of the stock hard tanks on either side of the engine in the mighty Malibu Wakesetter VLX. I'd like to have them fill at the flip of a switch rather than doing the pump-in-the-water thing. <BR> <BR>The simplest way I can think of doing this is to run the overflow hose from the current hard tanks directly to the bottom of each of the sacks. That way the sacks will fill up after the hard tanks are already full. Then I would run an overflow from the top of the sacks out the stock overflow holes on the side of the boat. <BR> <BR>For drainage, I'd be counting on gravity to send the water back through the line from the sack to the hard tank as the hard tank is drained via the stock pump. <BR> <BR>This sounds way too simple for it to actually work. What am I missing?

That is the way I'm going to try it (2006 X-Star). <BR> <BR>The (possible) problems and downsides of this system; <BR>- once the sack starts filling the pump will get more and more pressure to deal with. In the X-Star, there is 800lbs on each side of the engine, so the pump will have to work hard. <BR>- there is no easy way to get the sacks out. I prefer to remove the sacks every time to allow the carpet under the sacks to dry. <BR>- it is hard to tell at what point 'only' the standard ballast is full. For if you want to run that way.

I would also include quick release connections to the sacks so that they could be easily removed and dried. It would also have valves that would switch off the sack plumbing in case you didn't want to run with the sacks. <BR> <BR>I actually would rarely use this system because the wake on my boat is pretty incredible with stock weight and a few Pop bags. However, I do occasionally pull pros and other riders that want things completely maxed out, so it would be nice to be able to easily add some sacks. <BR> <BR>You make a good point with the workload on the pumps. I'm assuming they currently fill from the upper portion of the tank so there is little or no pressure on them while they work. This system would definitely put them to the test.

What you might consider is: <BR>-Installing a split Y ballcock valve on the fill/empty line of the hard tank. <BR>-Run a new fill line from the open spot on the Y valve to the external sack <BR>-Keep the stock overflow, but install an open Y adapter in the overflow. This will allow you to branch in to the stock overflow and add an overflow for the sack. <BR> <BR>The only thing you need to do to fill/empty would be turn a valve selecting which tank or sack to fill. The overflows will work the same, so you will have a signal of when to switch. <BR> <BR>If you install as you described, i think you might run into trouble when you are emptying. The pump may attempt to suck more water than gravity will allow through the tubing, thus running your pump without adequate water= possibly burning an impeller up. <BR> <BR>Just my .02cents

Ahh yes, I see that my design is actually trying to pump water out through the same tube that I'm using to move water from the sack to the hard tank. Duh!!

I think Malibu is concerned about extra weight in the back compartments also that could crush the tanks below deck. They rate the floor at 75lbs. Are you also going to re-enforce the floor?

No, I've been putting all kinds of weight on that thing. I'm not worried about the tanks collapsing. I could maybe see a concern if the tanks were empty, but I think you're fine as long as the tanks are full of water. I'm 200 lbs and I stand on them empty and full. Obviously, Malibu has to put that warning on there to cover themselves, but they are pretty beefy tanks. <BR> <BR>That being said, I'm certainly not condoning that anybody flagrantly disregard their warning stickers! <IMG SRC="http://www.wakeworld.com/MB/Discus/clipart/happy.gif" ALT=":-)" BORDER=0>

ha ha.... you heard it hear.... a pillar in the wakeboard community is condoning it... it must be ok...... <BR>ha ha... <BR>will be anxious to see how it turns out...

Yes, you are correct Dave. I think if you combine the tank and sack like in your design you will fill decently, but emptying might be an issue. The valve will allow you to treat the tank/sack seperately. <BR> <BR>Im not familiar with the Malibu ballast systems, but it seems that most all ballast systems use the same plumbing formula of check valves and overflows. <BR> <BR>Does Malibu use the Jabsco waterpuppy pumps?