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Rear Ballast Vent Location


trace

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I'm in the short rows of my ballast upgrades, and I need to decide where to put the vent thru-hulls for the rear sacks. I'm using Flyhigh 750's in back, and the vents need to be above the tops of the sacks for them to automatically fill completely. The 750's come well above the rubrail when full, which makes locating the vent difficult. I am considering moving my gas tank vent, and putting them in these spots:

thruhulls.jpg

This is the only place above the rubrail that I've found that'll look halfway decent, but they will shoot up and out from the back of the boat. That may look stupid, and might hinder use of the swim pform a bit when they're in use.

Also, I would have to relocate my gas vent. Any suggestions on where to put that? I was thinking just under the rubrail, somewhere near the gas fill.

The only other idea I came up with is putting the ballast thruhulls under the rubrail, but way forward - like under the windshield. This would make the vent lines really long, though, not a good thing.

Thanks for any help.

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I'm in the short rows of my ballast upgrades, and I need to decide where to put the vent thru-hulls for the rear sacks. I'm using Flyhigh 750's in back, and the vents need to be above the tops of the sacks for them to automatically fill completely. The 750's come well above the rubrail when full, which makes locating the vent difficult. I am considering moving my gas tank vent, and putting them in these spots:

thruhulls.jpg

This is the only place above the rubrail that I've found that'll look halfway decent, but they will shoot up and out from the back of the boat. That may look stupid, and might hinder use of the swim pform a bit when they're in use.

Also, I would have to relocate my gas vent. Any suggestions on where to put that? I was thinking just under the rubrail, somewhere near the gas fill.

The only other idea I came up with is putting the ballast thruhulls under the rubrail, but way forward - like under the windshield. This would make the vent lines really long, though, not a good thing.

Thanks for any help.

As long as the vent hoses loop up that high, why cant you just place the thru hulls in the standard location? :unsure:

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As long as the vent hoses loop up that high, why cant you just place the thru hulls in the standard location? :unsure:

i agree. put them on the passenger side at the same point where the mls discharges on the drivers side. loop the hose to the top of the storage compartment and you will be good to go. I think it will look bad in the position you have chosen.

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I've heard that recommended before, but if my physics are right they could siphon down to the level of the thru-hull anyway.

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Thanks for the help, but I'm trying to avoid putting manual valves, especially on vent lines (forget to open them) and in the rear lockers (hard to get at).

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Also, I would have to relocate my gas vent. Any suggestions on where to put that? I was thinking just under the rubrail, somewhere near the gas fill

moving the vent is a good idea, mine is underwater when we surf regular side. I think the newer boats have the vent in front of the gas fill, bicbw.

The only other idea I came up with is putting the ballast thruhulls under the rubrail, but way forward - like under the windshield. This would make the vent lines really long, though, not a good thing.

why is this not a good thing? From your picture it looks like the spot below the rubrail where the MLS discharges is about level with your proposed holes. Could be an optical illusion though.

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with the sacs you do not need a vent hose, went out of my way to hook it up took it off the first day at the lake. When full the sac will overflow at the drain line but, the sacs are so big that I could not get a loop to stop the drain side from siphoning off without a valve.

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Well you asked for it...JMHO It will look like crap. Tongue.gif

That's exactly what I'm looking for... I'll have to sell this thing to one of you suckers some day! :)

I'm trying to keep the vent lines short to minimize backpressure and chances for kinks.

I was thinking the same thing about the gas vent location.

edit - If the vent is below the top level (with gravity) of the sack, and you get a siphon started, over time it will drain down to the level of the siphon no matter how high the loop is. It might work if the loop was 33' tall (pressure of the atmosphere measured in feet of water), but an aerator pump couldn't pump it that high.

The more I think about it, though, I think I should put them up under the windshield. I could probably get the fittings just above the top of the sacks, and the head loss through the length of hose would make up for some height.

Edited by trace
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I don't think they would look that bad. Then again, anything you can do to make it look more 'factory' the better your resale will be. So go with the normal ballast placement if possible.

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with the sacs you do not need a vent hose, went out of my way to hook it up took it off the first day at the lake. When full the sac will overflow at the drain line but, the sacs are so big that I could not get a loop to stop the drain side from siphoning off without a valve.

RiverRunner,

Try attaching another small tube at the top of the loop and run it as high as possible. If this small tube is long/high enough than you won't get water thru it, but when a siphon starts it will suck enough air back through the tube to break the siphon. No valve required.

Disclaimer: I haven't installed any sacks, but I've drained enough fish tanks with siphons to know this little bit of air will be enough to stop it.

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RiverRunner,

Try attaching another small tube at the top of the loop and run it as high as possible. If this small tube is long/high enough than you won't get water thru it, but when a siphon starts it will suck enough air back through the tube to break the siphon. No valve required.

Disclaimer: I haven't installed any sacks, but I've drained enough fish tanks with siphons to know this little bit of air will be enough to stop it.

That's a great idea, you could put a check valve in the line and stop all water flow. Basically a vacuum breaker. www.usplastic.com has a good selection of small stuff like that.

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RiverRunner,

Try attaching another small tube at the top of the loop and run it as high as possible. If this small tube is long/high enough than you won't get water thru it, but when a siphon starts it will suck enough air back through the tube to break the siphon. No valve required.

Disclaimer: I haven't installed any sacks, but I've drained enough fish tanks with siphons to know this little bit of air will be enough to stop it.

That's a great idea, you could put a check valve in the line and stop all water flow. Basically a vacuum breaker. www.usplastic.com has a good selection of small stuff like that.

A check valve.... why didn't I think of that? Hope this works. Let us know how it goes

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RiverRunner,

Try attaching another small tube at the top of the loop and run it as high as possible. If this small tube is long/high enough than you won't get water thru it, but when a siphon starts it will suck enough air back through the tube to break the siphon. No valve required.

Disclaimer: I haven't installed any sacks, but I've drained enough fish tanks with siphons to know this little bit of air will be enough to stop it.

That's a great idea, you could put a check valve in the line and stop all water flow. Basically a vacuum breaker. www.usplastic.com has a good selection of small stuff like that.

A check valve.... why didn't I think of that? Hope this works. Let us know how it goes

Check valve won't work. You need a siphon break. Ask your dealer to order you one of them from Malibu. They use them on all of the new ballast systems. You can see them mounted on the back of the rear seat in the VLX

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In line check valves work just fine.

I use them on my rear sacs.

I used the big fat ones from home depot - brand is Brady.

Get the 1" ID ones and reduce it.

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