Submergible Slider / Box Slider

Has anyone built a submergible slider or box slider?

We’ve been told that around here the Coast Guard will go around and tear out sliders. It seems true because we’ve seen them built up, then they disappear a few weeks later. So we were thinking about building a submergible slider.

There’s a lake here that has a buoy marked slalom ski course and a few misc anchor buoys that the wake boats tie up to while other boats run their sets. This lake ranges from 2 feet (mud) to 10’.

My initial idea goes like this:



You pull up to an unsuspecting bouy and tie the boat to it. Pull the 12v wire out of the water and start pumping water from the bottom of the drums. Pull the air hose (red) out so it can pull air to replace the water. Eventually, your slider raises from the dead.

To re-sink, use a separate fat-sac pump to inject water into the spout of the pictured pump fixed pump. This will force water through it in reverse, filling the drums. Once the thing sinks, pull the fat-sac pump off and let it go to the bottom. Plug your air vent hose (red).

Thoughts, ideas, am I crazy?

Perhaps a high-volume air-pump on the boat would be a better choice than a water pump..

pretty cool idea, only thing i'd be worried about is crap like algae growing on it, but that might just be my lake.

good point...but no algae here.

after doing some math, each 55 galloon drum is going to provide ~475lbs of floatation. I think 4 drums is overkill. Instead, I think I'll do two drums, one on each end, in perpendicular configuration to the ones that are pictured above.

You would need to make sure that the drums stay level so that one doesn't rise before the other making it impossible for the pump to reach the water in the lower drum. At first glance, they would appear to stay level, but in the event that they didn't, you may need a pump for each drum. Just my .02

Very cool idea by the way. I hope you can pull it off and take some pics of how it works.

that's another good point. I didn't envision that when I was visualizing the operation of this thing.

I did find that I'd only have to pump about 3 gallons out of each (metal) drum to get the thing to float. Then it'd pump the last 52 gallons out to raise it all the way ontop of the surface. If I used plastic durms It'd be even less. In fact, I think I'd probably need ballast to sink it. Wood, Plastic and Teflon slider surface should all be naturally buoyant.

(Message edited by yosquire on September 14, 2006)

A couple of thoughts:

1) You are not going to hide this in 2 feet of water! If it isn't sunk so that the highest spot is at least 4 feet underwater when the lake is at its lowest point somebody is going to run into it, and that someone isn't going to be happy with you.

2) I doubt that the submersible pump that you reference will do the job. If the top of the barrel is four feet under water the pump will need to pull air down four feet. The pump will need to be able to generate at least 2 PSI to do that, and many of the submersible pumps will not do that. If the lake is full and the barrels are down deeper the pressure requirements are even greater.

You would be better off pumping air down from the surface. You need a hose running to the surface either way, so just carry the inflation pump with you in the boat. Besides, one less thing to lose if the slider gets taken out.

You will want a lot of "overkill" on the floation. If you build the structure out of wood then you will need to add ballast in order to get it to sink. You may also want ballast down low to give it a low center of gravity so it resists tipping over.

Very cool idea, and I am sure you could make it work...but here is my question: would it just be cheaper to make a "tear down" slider that could be quickly dissasembled, and put in the back of a truck or something? Might save some engineering hassle, and make it safter for the salalom..ers

i thought about the same idea. Here is how I was going to solve it. Instead of pumping in or out water. Pump air from a compressor above the water into the top of the barrels. The average compressor is 120psi, if you have a hole at the bottom of the barrel then the air coming in the top will force the water out of the bottom, lifting the slider. To submerge it, you just disconnect the airlines or uncap them and the water will come flooding back into the barrels.

The problem with an air compressor is that it will deliver a lot of pressure but not much volume.

To empty 4 55 gallon drums you will need 4 x 55 gallons of air, or 220 gallons. If you wanted to pre-fill an air storage tank to 120 PSI and use it to fill the barrels you will need a storage tank of 25 gallons. That would be one large and heavy tank!

A 12 volt compressor capable of producing 120 PSI would take a long, long time to pump 220 gallons of air.

I would think that the best way would be to use good old manpower to haul the slider up from the bottom. Fully submerged it wouldn't weigh that much, so as long as it didn't sink into the mud or get covered with weeds it wouldn't be hard to lift it up to the point where the top of the slider was just breaking surface.

With the barrels only a few feet below the surface 2 PSI would be enough to do as mike describes, which by the way is how the typical hydrohoist works. At this point you could use a 12 volt raft inflator . Something like this would empty the barrels in about 2 minutes.

Check out how floating boat lifts work. Usually pumping air in to raise the floatation and opening a valve to allow air to escape. Their designs are time tested and will give you ideas. If they are used in your area you might be able to get an old single tank that will do the trick. Based on the amp draw of the blower you might be able to run a power inverter and use a standard air pump or heck even maybe a gas powered leaf blower if it can generate enough pressure.

Your best and simplest bet is to check out existing designs. Also, as others have mentioned, make very sure it won't be a hazzard when submerged and make sure it is visible at night if the lake gets night traffic (simple reflectors should do).

What about if it's only a little below the surface. You want it on a ski course. ... What if that person falls, and injurs themself on your slider?

That could be a law suite waiting to happen.

Someone above mentioned a "break down" slider. That's my vote too.

my concern would be the slider rotting away under water. pressure treated or not, there may be some issues, theres always a weak link somewere. I dont know that for fact, just a thought, assuming you figure out a design

The place where the slider would be setup is 10 feet deep when the water is low. A 3' tall slider isn't going to hurt anyone. (no night traffic on this lake. But reflectors are cheap.)

I do like the idea of pumping air down to the slider. But, It's difficult to find a 12v high volume pump that's capable of delivering 15 psi. (At 20 feet the water should be at about 9.09psi.)

I'm also worried about the slider rotting. Perhaps steel is the best way to go for the structure. (I'm trying to keep this somewhere around $100-$200.)

I just had some thoughts occur to me. Add styrofoam so it's closer to being neutrally buoyant. Lets say it weighs 10 pounds in the water. Then use a foot pump to pump in the .16 cubic feet of air to get to surface. Once surfaced, switch to the 12v Inflatable pump to handle the high-volume task.

(Message edited by yosquire on September 17, 2006)

http://www.familydefense.com/jump-start.htm


Air Compressor: Up to 250 psi inflation, 25" air hose with universal adaptor, ...

And you can jump your boat, if you get stranded.

i say you just build a slider that floats... anchor it down... and when you are done with your session you hide it or pull it out of the water. this whole sinking and raising thing seems like way more trouble than it's worth.

I'm sure sinking and surfacing it is far less trouble then dragging a slider 1.5 miles, disassembling it (as it'll be at least 20 feet in length), Then loading 150 - 300lbs of awkward 8 foot sections into a truck... Can't have it longer than 8 feet because it needs to fit into the truck bed since I'll be pulling a trailer...then unloading it at home. Not to mention, I tow with a Suburban. This concept simply takes a little math and engineering to make it work.

Besides – Thank you, but pulling it in and out of the water is outside the scope of this thread and we're not tallying votes for most popular design.

Robb,

I'm concerned how much volume those pumps can deliver. Generally high PSI pumps are low volume and vise-versa. I've watched one of those pumps inflate a tire from flat. This particular pump took 20 minutes to do a tire.

As I consider this as a winter project, a new design objective surfaces in my mind. Floating in under 10 minutes total. Conversely, sinking in under 10 minutes..(this should be the easy part)

I still think that manually hauling the rig up from the bottom would be the best, then use a high volume, 2 PSI raft inflator to get it floating.

You might want to consider NOT having a marker float, or at least not one that floats on the surface. Someone is going to see it, wonder what it is and pull up your rig. Others will see you using your rig and then want to use it themselves. Others will be annoyed that you are using it and will take the opportunity to destroy it.

You will want to have an anchor that will lock down exactly where the rig is at. I would recommend putting a small float on a line that would float up just a couple feet above the rig when it is sitting on the bottom. When you want to retreive it reach down with a boat hook or grappling hook to snag the float and haul the rig up.

Without a visible marker it will not be as obvious that it is there. If you have a means of raising it without a surface marker then you won't have any concerns about the marker disappearing, either by intentional acts or simply a boat running it over.

What about using some foam to make it raiseable manually like Rod suggests.(just lest than neutral at the surface) Dive down unhook from the anchor and use a haul line to pull to the surface. Then open a gate on the side of the box and slip/work in the two barrels that you brought out from home. When done reverse the procedure. The only thing you have to haul is two blue barrels. Use a GPS to locate without a marker.
To make it work you might have to drag the thing to shallow water to get the barrels in place.