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Accusink


gapullin
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Interested in converting our Accufloat course to a sinking version. Planning to construct a "homemade" version of an Accusink, but if anyone has a used Accusink or Wally Skier available at a reasonable price, I'd appreciate a reply. Also, if anyone has pearls regarding construction of a sinking unit from scratch, feel free to provide input.

The course is in variable water depth from 25-100 feet. Plan is to use 5 gallon sealed pails for air bladders with slightly positive buoyancy when saturated, and lead weights dangling about 10-15 feet above bottom attached to the pails. When the course is sunk, this will keep it at an even depth. When the pails are air filled, the combination of buoyant pail and negatively buoyant lead weight creates slight negative buoyancy, just enough to hold the assembly down.

1/4" high pressure air hose will supply the needed compressed air, provided by a refillable portable compressed air tank.

Thanks in advance for input.

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If doing 5 gallon buckets buy inner tubes put them into the buckets and perforated the bucket so it fills with water. The inner tubes will then expand in the confines space and displace water. What wallysinker figured out is that rigid pressure chambers cause problems as water can accumulate in one chamber or several chambers and cause failure to float.

 

The genius of Wally is using a vacuum pump enough water is able to be extracted that it will float.

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Not that it matters - but I think he's in New Zealand, they might not be so zealous about lead weight. Its probably not all that hazardous to use in this capacity.

 

Think about growing up, how many of you guys used your teeth to bite lead sinkers onto the fishing line?

 

Solid lead poured around a stainless eyebolt won't go anywhere and is about the most weight/size/cost that you could get.

 

Dip the whole thing in plasti-dip or epoxy flooring paint.

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I'm not throwing this out there because I know its a problem, but because I recall some sort of problem with a friend's accu-sink course related to variable depth to bottom of lake and the different pressures required at each end and the fact that beyond 30 feet deep you are at an additional atmosphere and the deep end didnt fill at rates needed to fill the shallow end, or something like that. 100 feet is 4 atmospheres. That's quite a bit. Anyone have any idea what I am talking about?

 

Also my own question. Never thought about a "homemade" accusink. Do all 22 balls need to be bladdered and weighted or just some or most and the others will follow along?

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Thanks for the comments. I'm in British Columbia. No issue with lead up here. As far as variable depth goes, not an issue, only the lead "sub weights" sink to the bottom. The buckets/bladders sit about 15 feet (1/2 atmosphere) below the surface. Love the idea of air bladders, of course this will likely require a vacuum pump to extract air, otherwise I think they might drain quite slowly. My original plan was to use the pails themselves as air reservoirs. That plan involved about 20kg of concrete poured in the bottom of the pail with a hollow tube entering the bottom of the pail and travelling through the concrete. Opening a valve at the inflate end of the high pressure hose allows air, which of course is lighter than water, to drain out, permitting water to enter the pail through the tube. Once all air is displaced, the bucket will sink, with the assistance of the lead weight dangling 15 feet above the lake bottom. Once the weights hit bottom, the course remains suspended 15 ft below the surface.

Using compressed air through a Shraeder valve on the surface will displace the accumulated water out the bottom of the bucket through the tube and allow the guide/turn balls to float the pails and lead weights.

I think the advantage of inflatable tunes is that they will create a more reliably sealed system that is less prone to leak over time.

Does all this sound reasonable?

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One comment on the bladders/buckets.

 

If you use buckets you will need to create a means to pump/vent the air out and displace it with water to sink the course. Then you will need to displace the water with air to float the course (the hard part). If you use bladders the pressure of being underwater will work in your advantage because they are flexible. The water pressure will force the air out when sinking the course, then all you need to do is re-fill the bladder with air when you want to raise it.

 

Trying to displace water with air underwater is very difficult, so I would chose to eliminate that challenge if you can.

 

Much simpler to use a flexible bladder bag then a rigid air container from a physics perspective. You'd only need one valve for the whole course. Connect all the bladders together, pump air in to raise the course. Vent the bladder air to the atmosphere to sink it. If you want to get really fancy get a Belimo, arduino and a contactor. You can start the compressor and actuate the valve with a remote.

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@BrennanKMN - that's the purpose of using small inner tubes (like wheelbarrow) in the top of the bucket, air lines to the inner tube fitting, pull the cores out.

 

You want small diameter lines - the larger they are the more they float and the more air it takes to achieve a certain pressure in the bladders. You want a vacuum pump to extract the air - as mentioned by @thager. If you just let it vent to atmospheric you can get the situation where water etc. leaks into your lines (no matter how careful) and eventually it blows into a certain bladder which no longer will float. By pulling a vacuum that water gets brought back up the lines as the bladders collapse and it avoids that issue.

 

The buckets essentially are variable displacement subbouys as if you try to contain the inner tubes or tie to them they'll rupture. I would actually investigating making them out of thin wall PVC maybe 8" diameter with perforated end caps and loops of rope at both sides for clips.

 

Then it would be very modular.

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Ah. Yes. I didn't see bladders in the buckets in original post.

I've never had an issue with just atmospheric venting, but maybe I am gambling...

 

My favorite submersible design is a guy that used large diameter PCV pipe for his course arms and put tubing inside the pipes and inflated that. Had the weight and pressure set just right to have it be neutral buoyancy when in use and heavy enough to sink without air. Probably not something that would fair well on a high traffic lake.

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I have experience with both accusink and Wally. Really cool concepts and Wally was really helpful. My only counsel is that while you are generating you budget for pieces and parts, set aside triple that amount for gifts, trips, jewelry, etc for your wife. The hours that i’ve spent working on air pressure sinkers are countless and those were factory spec.
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@thager Oh perfect, I will search or if you get a pic of it. Yes, I have a homemade/accu sink combination course that has evolved over the last 2 decades, and a cinderblock is about the right weight, then you can add donught type floats if you need some lift, as they don't compress under a deep lake bottom.
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@gapullin, I'm curious how you made out with your DYI sinking system. Did you get it working? How did the process go?

 

I went with the WallyCourse/WallySinker combo this year. I figured it would be best for me to go with a system where someone else worked out all the bugs. I completed putting it in about 6 weeks ago and so far so good. It takes 8 minutes to raise and 12 minutes to sink. It took me quite a while to install it, but now that it is up and running I couldn't be happier. Very high quality components and Wally provided great support through the process.

 

 

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@coach3 I used mine the other day to suck some water out of the system. Got a couple gallons out maybe. Only have to do it a couple times a year. Have never collapsed a chamber but as suction increases I reach a point where the air tube collapses and suction stops. That's when I turn it off. You can hear the sound difference.
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@thager Big thanks. Yes I wondered if collapsing an air bag could be an issue. I have an old course, 20 years, and have modified over the years. I have 9 ball valves to force water out, with a compressor at the dock. A little suction may speed up drying out occasionally; hopefully.
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@thager So you use suction from the dock and not at places on the course? I raise it from a dock compressor as well. Your 110V suction pump is just used from the dock to raise and lower I assume?

I wonder if I used a 12v pump to suction at water places in the course from the boat? My dock to course line is 800 feet to the course. (3 gate)

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I only suction from the dock. I can raise and lower with mine but normally use a small pancake compressor to raise mine. Is a little faster. A 12V would be nice when you get that one stubborn sub float that is full of water. Pretty rare in my experience.
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