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fever5

3 Fat Sacs, 1 pump, filling in serial; is it possible?

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fever5

I apologize if this has been addressed, but a quick search and past browsing has not revealed any info on this.

Problem: I use 3 fly high 750 lb fat sacs (stern, mid, bow) on port side in addition to port sided MLS system for surfing on my '07 VLX. However it's a huge pain with a loaded boat to move around people to fill all bags (~5 min each), not to mention I have to be there. I don't want to hard wire anything yet...

Solution(?): Speed isn't an issue, I just want to fill the 3 bags with as little attention as possible.

I am thinking of taking the Tsaunmi pump and connecting it like normal to the first bag (at top). The vent of the first bag would be connected by tub to the fill port of the second bag. The second bag vent hole would have a connected tube going to fill port of third bag (slightly higher elevation in bow then the previous two). The vent port of the third bag would have a hose that goes over the side for overflow precaution.

I realize there will likely be some air trapping in each bag due to kinks in material higher than vent port. The hydrostatic pressure in each bag against line should be minimal as the tubes will all fill from top. Does this serial fill seem possible or am I missing something? (I realize using one pump to three bags via a splitter (i.e. parallel system) would work for sure, but it would mean more tubes...)

Thanks for reading, and in advance for any comments.

EDIT: Picture (google doc) Link (google doc)

Edited by fever5

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martinarcher

Obviously your first bag will fill the fastest, but after pressure in that bag increases it will certainly push water up the chain to the next bags. My system is a parallel with two bags on 1 Tsunami. I don't see why what you are suggesting wouldn't work. You are right parallel plumbing is more tubing so you would certainly simplify plumbing. I do leave the drain open on my bags (no vent) so I can turn the pump on and be busy with other things. Once the pressure in the sacs builds and they are full, it just pushes incoming water out the drain and also serves as a priming action for the drain pumps.

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chathamsolutions

3 750lb Fly High bags and 1 pump. Dude, it will take all day.

Where you putting those bags if you have 5 people, and you, in the boat? Your folks will be moving, just out of the way of those bags.

Really, it would be hard to keep the lines all straight and from getting kinked if you seriously are putting one in the bow, one midship and one in your rear locker (won't fit too big), or on the rear seat. You'll be running around fixing them anyway.

IMO, the simplest way, since you say you have 5 other people in the boat, is to just get it done faster. Buy three pumps and fill them up quickly, then be done. You'll also empty faster this way too.

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Brad3607

I am in the middle of a ballast project but have been throwing a 750 gph pump over the side and filling two 750s that a chained together and it takes about 12-14 minutes to fill them and about the same time to drain them. Your plan will work.

Brad

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chathamsolutions
I am in the middle of a ballast project but have been throwing a 750 gph pump over the side and filling two 750s that a chained together and it takes about 12-14 minutes to fill them and about the same time to drain them. Your plan will work.

Brad

It will just take 21 minutes. Dude, that's unacceptable in my world. Time on the water is critical.

If you live on the water and your crew is happy to sit around for 20 minutes while everything fills - you're good. Just seems like a waste when it cost you $150 to fill that tank, spend a couple more bucks and buy a few more pumps and put those guys to work filling and you'll be done in 6-7 minutes.

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saburkhart

I would also be concerned about the pressure in the first sac. In order to fill the second and third sacs you will have all the pressure in both sacs pushing agains the first sac. Seems like too much potential to burst the first sac to me. Plus your pump will have to push against all that pressure when filling creating a slow fill time

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Lance B. Johnson

Im not sure but I just don't see this working. seems like you would have to much head pressure for the pump to push against. Even if it did work it would only work very slowly.

I am sure there is a solution for you somehow. I would just buy another pump and have your crew help fill the bags. Only a little more money than the fittings and hoses on the system your talking about.

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skicrave

We've had a few customers try to go this route, and ultimately (other than just buying more pumps) the best option is to fill the bags in parallel, and not in series. That means splitting the flow from the pump three ways so all bags fill at the same time.

The bigger issue you're going to have is that because the Tsunami is an aerator pump it is not self priming, which means that you'll have essentially no way to drain the bags. If you want to go this route you're better off using a reversible pump like Jabsco's Ballast Puppy which can fill and drain all three bags at the same time. But for less money you could have three Tsunami pumps, which will take a third of the time to fill and drain.

Ultimately, our customers end up using individual pumps or integrating their bags into the factory system so it's all done from the driver's seat.

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