After spending way to much time burping fat sacks on a Hippo system and not wanting to spend the money on new sacks, I figured out how to easily add more fittings to the sacks. Took about 15 minutes/sac and cost about $0.70 in parts from Home Depot. <BR> <BR>Basically, buy a 90 degree elbow for 1/2 inch PVC pipe that connects two pipes (one side accepts the pipe for the connection and the other side is the same size as the PVC pipe). Buy two for every sac you want to add a fitting to. <BR> <BR>Depending on how thick the material the sac is made out of, sand down the small end of one of the fittings. Once it is sanded to allow a very small amount of space, cut the angle end off with a saw (rather than use a 90-degree angle piece, you can use a short piece of pipe, but sanding is a lot easier with the 90-degree fitting to hold onto). <BR> <BR>Place the short piece of the fitting inside the sack through an existing hole. Place the larger end of the other 90-degree fitting on the outside of the sac. Use a wooden dowel to tap the part inside the sack into the part outside the sack. This pinches the sack between the two. Pierce the material in the hole and you're done. <BR> <BR>The outside diameter of the 1/2 part of the 90-degree fitting that is now outside the sack is the correct size for a 3/4 inch bilge pump hose to attach to with a hose clamp. <BR> <BR>I did this with two sacks and all is holding really well (so far) <BR> <BR>Hopefully the instructions above make sense. A quick and cheap way to add vents to sacks for anyone using aerator pumps.

Dood, Your an Effing GENIUS!!!!!!!! <BR>I have recently been thinking about how this could be done. Please post pics! <BR> <BR>I also have the need to add vent holes to my <BR>exsisting bags. My whole ballast project has <BR>been hinging on whether to buy 2 more simer pumps <BR>or to replace all my bags. What you have suggested is the ideal solution!!!!!!!! <BR> <BR>I wonder is just a little rubber cement would <BR>ensure that sucker is permenant! <BR> <BR>Also, I don't see why you couldn't go with <BR>a bigger size for less restriction. <BR> <BR>I will attempt this ASAP. <BR>worst case senerio: It doesn't work <BR>and, I buy new bags anyway! <BR> <BR>

Ahh... can't go bigger. One piece has <BR>to fit thru the exsisting hole.

I did this with a walkthru sack two years ago. I will post pics after the weekend. Very easy and efficient. I can burp without getting any water in the boat at all...the sac that is! <BR> <BR>KG

Yup...can't go too much bigger because you need to fit part of it through the existing hole. But since I am using it for a vent, I don't need any bigger since the bags fill up reasonably slowly. You could probably go to 3/4 if you were going to use it for a drain or fill. <BR> <BR>I thought of putting cement on it, but after testing it with a piece of a broken pool toy, there is no way it will come apart before the vinyl will tear. The nice thing about the PCV pieces is most have nice rounded edges (or you can sand them to be round) to prevent tearing along the new seam. <BR> <BR>I'll try and remember to grab some pics tonight.

I think I understand, but I'd like to see pics also. I'm going to try this on my ghetto waterbed tubes !

Yep, me too. Pics please.

I am going to do the ski locker sac tonight and will take some pics. I know the description may not be very clear, but it is really really simple to do. The pics should help a lot.

Instead of using 2 elbows per sac, could you just use a short piece of PVC tubing on the inside? If you made it the same length as the female end of the elbow, it would sit flush at the top of the sac. I think this would work, but I am not sure. I am trying to figure out a way to do this to the multiple waterbed tubes I use in my system. I can do it for the twin matress in th eski locker, but I use 5 tubes in the back of my boat also. Not sure how to make them work without several valves and cehck valves. I guess I can try to figure out which bag fills last and add on to that instead of adding one to all of them. Any thoughts?

Chris, <BR> <BR>That is exactly what I did. The reason I used the two elbows was I needed to sand down the male side of the second elbow to leave some room for the thickness of the sac material. It was A LOT easier to uniformly sand it with the elbow on there. Once it was sanded, I cut off the male end and it was the perfect size to sit flush when installed into the first elbow.

I hate to say it, but I am lost on this since I can't picture the elbow you are using. If I saw that I would be able to visualize what exactly you are doing. As soon as you have a picture available, please post it. <BR> <BR>Thanks.

It took me awhile to visualize Shawn's idea, but here's my guess. Anyone, please correct me if it's not quite right.....here you go Chris (since I'm having a hard time sleeping): <BR> <BR> <BR><img src="http://www.wakeworld.com/MB/Discus/messages/65921/68137.jpg" alt="fitting">

Ral is exactly right....that diagram is better than a picture. Since you need to keep the 1/2" OD part perfectly round, having the elbow to hold onto while sanding a big help. Wrap sand paper around it and rotate it with the elbow. <BR> <BR>Put the gray part in number 3 inside the sac and the white elbow outside. Use a hammer to lightly tap the gray part into the elbow, pinching the vinyl between the two (I used a piece of a broom handle to reach inside the sac). Tap it in so it is flush on the inside and then connect a 3/4" hose (standaard bilge hose works great) to the elbow outside the sack.

The only problem I see with this set up is <BR>the 1/2 restriction. If the rest of the plumbing <BR>has a 3/4 mimimum and you restrict the vent to <BR>1/2"... there is still a possibility of bursting <BR>a bag if you are not paying carefull attention. <BR> <BR>If it is possible to get a 3/4" peice <BR>into the sac the vent will be able to keep up <BR>with the pump and would piss out the vent all <BR>day if you let it.

that's a reasonable concern Sandy, but in my system and almost every system that I have seen so far, the diameter of the hose to or from the bags is not the limiting factor, so the small 1/2 inch restriction in the elbow is a minor concern. If you were using biger hoses, a 3/4 inch fitting would work. I used the 1/2 inch stuff because the hoses fit.

Thanks Ral, I see it now. Of course it all makes sense to me now.

Sorry for being dense and holding up the rest of the class, but I still don't quite get it. I understand the installation, just not the application. Is the point to put it on the bottom of the sack so you drain from the bottom? If on the top, how is it better than the holes that are already there?

Mike, <BR>Its purpose is to make a two hole sac into <BR>a three hole sac. <BR>With three holes in each bag, its better for <BR>an automatic ballast system. <BR>One hole for fill. <BR>One hole for drain <BR>and one to vent the bag to "auto burp" <BR>and prevent the bag from over-filling and possibly bursting. Its the best way when <BR>using aerator pumps. <BR>Most bags (until recently) were only available <BR>with two holes. Shawn's solution will save a lot <BR>of people from having to go out and purchase new three hole bags to upgrade their ballast systems to push-button-automatic. <BR> <BR> <BR> <BR>

I have now put about 10 fill-drain cycles on the PVC vents that I added and the results have been outstanding. The sacs fill completely without any attention and when they are full, the vent lets the extra water go to the drain, making it easy to gets the sacs filled equally and know when they are full without looking in the storage areas. <BR> <BR>I do need to add some sealant to one of the fittings because the material that my ski locker sac is made out of contains a fiberglass weave. It makes it super durable, but the seal isn't 100% tight since the fiberglass isn't as strechy as the vinyl. <BR> <BR>Another reason to go the home-built route is you can put fittings anywhere on the sac you want for your application and save a fair bit of money. For example, the Lets Go Ride sacs are $75 for one that has the standard two valves. If you order it with 3 valves, the price jumps to $120. Multiply that across three sacs and you're looking at a $135 difference. <BR> <BR>Including all fittings, hoses and parts, it was less than $20 to "modify" three sacs and have the ballast system be 100% automatic. Now I just need to get it to fill a bit faster.

I see. Thanks Sandy.

May I suggest buying LAUNCH PADS at 540# each and they have four holes for filling, draining, and venting! That's what I have in the rear of my VLX and it works great.

Mike O, <BR>I think this thread is specifically <BR>meant for people who already have several <BR>perfectly good bags with two holes <BR>and don't want have to buy new bags just to add <BR>a vent hole. <BR> <BR>Did you actually read it?

I took a quick look around for the launch pads and didn't find them on-line anywhere. Obviously I didn't look in the right place, but Overton's, Barts, etc didn't have them. The only thing I could find was the launch pad lounge. <BR> <BR>Anyway, the point as Sandy said) is you can use a sac you already have or even purchase a less expensive sac, spend 15 minutes and add a vent line. A month ago, I would have bought the launch pad sacks but this simple modification worked so well that I'd probably buy the less expensive lets-go-ride sacs and modify them if I decide to increase the weight.

Sorry, not knocking Shawn's idea, I was just letting you know that there is a bag out there that has four holes in it! I did not know they were available when I bought the bags, so for what it's worth to ya! I bought my bags from my dealer.

<a href="http://www.epicmarine.com/images/thumbs/drainandsack.jpg" target="_blank">http://www.epicmarine.com/images/thumbs/drainandsack.jpg</a> <BR> <BR>Here is a picture of a fat seat that I modified with a Rule 1.125 through hull fitting. Cost around 10$, it is a little more expensive but very strong and reliable.