55 Gallon poly drum lift

[mavryk]

Anyone ever built a lift out of 55gal drums? Just theorizing that it would be a low-cost alternative with some easily available parts. I'm thinking 10 drums aligned in two rows the end to to, all plumbed together and then to a water transfer pump on dock. They would be vented above the waterline. To raise boat, drive on to bunks, tie up to lift, pump water out of barrels. To launch, open valve to flood barrels. Ok, is this nuts? I think this could be done for around $500 total. 10 barrels would give 550 gallons of displacement, and should lift 4565#'s, correct?

 

[gm280]

Re: 55 Gallon poly drum lift

It could work but you will need some good AND fast water pumps to give you any quick capability... You have to exchange the water fast or otherwise wait for a long time for it to happen...

 

[mavryk]

Re: 55 Gallon poly drum lift

110V Water transfer pumps w/ 4800 GPH capacity would drain system/raise boat in about 10 minutes. Cost would be about $250. 10 minutes seems like a reasonable time for me, you could do some cleanup, unload, get the cover on, etc.

 

[smokeonthewater]

Re: 55 Gallon poly drum lift

why not used compressed air to blow the water out submarine style.

 

[jdlough]

Re: 55 Gallon poly drum lift

Last year someone was trying to sell something like this on Craigslist. It was there for months. I don't know if he finally sold it.

I also saw that some guy built a lift out of an old pontoon boat. He used pumps to fill and empty the pontoons.

This company makes something similar... Floating boat lift (for inflatable boats) - RIB590 - Airberth

Some people with their boats in canals near me use this....Air-Dock Boat Lifts - Home


I'd never have a floating boat lift. I need my boat totally out of the water due to tides, waves, current, storms. A floating lift would just bash itself up on my pier.

 

[mavryk]

Re: 55 Gallon poly drum lift

I *think* that it would be faster to pump the water rather than to blow the air. Maybe I am wrong.

 

[mavryk]

Re: 55 Gallon poly drum lift

I have seen the floating lifts for sale. I have also seen the pricetags. $$$$$$$$ I don't recall the name of the manufacturer, but one company builds docks very similiar to what I envision using square, hollow poly tanks". I think they use air to evacuate the water instead of pumping.
One of the attractions to me of designing/building this lift is that I anticipate using it in a concrete slip. The design would be such that the boat would be completely out of the water, and the barrels would give spacing/cushion between the sides of the slip and the bow. Also, it wouldln't require much in the way of "permanent" installation at the slip. The marina I plan to rent the slip from only allows lifts to be installed by their employees, as they want to be certain there is no damage to their docks, so I am looking to minimize the install time. Of course, before building this lift I would make certain the Marina was ok with the design. If I build it, it would be towable so I could do all the assembly, tow it behind the boat, slide it into position in the slip, let the Marina tie it off/attach it to their dock. Of course, if I decide to build this, I would give it a trial run prior to taking it to the marina.

Still looking for someone that has actually built one like this. The comments and advice so far are appreciated, but I am really hoping to hear from someone has tried to build one and can give first hand experience on how well it worked/didn't work.

Thanks

 

[camaro9488]

Re: 55 Gallon poly drum lift

Same principal as mine but mine has square tanks. It uses an industrial vacuum motor (Grainger $130) to blow air in the top, thus forcing water out the bottom through holes. To lower just let the air out.

 

[mavryk]

Re: 55 Gallon poly drum lift

Same principal as mine but mine has square tanks. It uses an industrial vacuum motor (Grainger $130) to blow air in the top, thus forcing water out the bottom through holes. To lower just let the air out.

Could you tell me the weight of your boat and approximately how long it takes to raise the lift out of the water? Is this a lift you built yourself or a commercially available unit?

Thanks

 

[smokeonthewater]

Re: 55 Gallon poly drum lift

yep it only takes a few psi... heck a shop vac could possibly do it.... MAYBE

 

[mavryk]

Re: 55 Gallon poly drum lift

yep it only takes a few psi... heck a shop vac could possibly do it.... MAYBE

How big a shp vac to you think it would take? Seems like it would neet a lot of power to force the water out. It would be nice if it would work with a shop vac.... would have it right there to give the boat a quick vac when was done lifting it out of the water. It would definitely be less plumbing to blow the system..... one check valve in the hose between the blower and the tanks, and a another valve downstream of the check to open and allow air out. Hmmmm..... gonna have to do some testing.

Still hopinig that someone out there has built one and can give first hand info.

Thanks

 

[UncleWillie]

Re: 55 Gallon poly drum lift

110V Water transfer pumps w/ 4800 GPH capacity would drain system/raise boat in about 10 minutes. Cost would be about $250. 10 minutes seems like a reasonable time for me, you could do some cleanup, unload, get the cover on, etc.

550 gallons is 74 cubic feet; A 10 cfm compressor is going to take 8 minute. However....
A 60 gallon air tank precharged to 125 psi already has 500 gallons(66cuft) of air in it.
You could blow ballast and surface in under a minute.
A plus is the air plumbing can be small.

The water plumbing will need 3 inch connectors between the barrels or the cross flow won't make it.

 

[mavryk]

Re: 55 Gallon poly drum lift

550 gallons is 74 cubic feet; A 10 cfm compressor is going to take 8 minute. However....
A 60 gallon air tank precharged to 125 psi already has 500 gallons(66cuft) of air in it.
You could blow ballast and surface in under a minute.
A plus is the air plumbing can be small.

The water plumbing will need 3 inch connectors between the barrels or the cross flow won't make it.

Thanks for confirming the numbers on the CF of air needed to evacuate the system. Do you have an equation that can be utilized to determine the PSI needed to evacuate the water? Is it simply a PSI value greater than the density of the water that is being evacuated? Does barometric pressure and/or air temp come into play, or is it of such small significance that it is not necessary to consider?

I like your suggestion about the ballast tank.... thoretically, if the fill holes for the floats were at the bottom, when they submerged the water would pressurize and "refill" the ballast tank if there was a bypass around the check valve, correct? How much air would be lost due to the fact it is not a truly "closed" system and the barrels wouldn't have a bladder inside to keep the air from escaping into the water.

I really appreciate the information.

Thanks

 

[smokeonthewater]

Re: 55 Gallon poly drum lift

no clue how big OR if the vac could develop the needed psi to begin the process....

an easy test though would be to decide how low the barrel would be in the water and put some extensions together... see if you can blow air that deep into the water.... be careful tho... don't wanna fall in taking the vac with you

 

[jdlough]

Re: 55 Gallon poly drum lift

If you're tank is near the surface of the water, and you're filling the air from the bottom of the tank (imagine air bubbles floating up into the tank, joining the air at the top of the tank, thereby pushing the heavier water out the bottom of the tank) you'll need less psi than you think. Anything over the standard atmospheric 14.7psi would do it. (And zero on an air compressor gauge really is 14psi, so according to your air compressor gauge, anything over zero would do it)

If your tank was sunk 33' deep into the water, that's an additional one atmosphere of pressure, so you'd need anything over about 14.7psi on your gauge to get the air down there to fill the tank.

At any rate, you need less pressure than you think. You do need volume, so a little 6 gallon air compressor will take a while. It's designed to build up high pressure, not high volume.

So, a Shop Vac exhaust hose is likely to work much better than a 150psi air compressor (unless your lift has sunk down way below the surface)

Assuming your tanks are 5' below the surface, the water pressure there is 16.9psi. Subtract the normal atmospheric pressure of 14.7 from 16.9. and you get 2.2psi. So you just need 2.2psi to get air down to your 5 feet deep tanks.

 

[mavryk]

Re: 55 Gallon poly drum lift

Great info. Thanks. It certainly seems like blowing the water out is the way to go. Here is design I have in mind. 10 55gal poly drums. I will use a 3/4"mip X PEX fitting in one bung of each barrel. I will homerun the PEX from each barrel to a manifold. Upstream from the manifold I will put in a check valve and a bypass with a ball valve. I will make a nice transition that will accomodate a shop vac/blower that will be located on the dock, plugged into a GFI. To raise, I will shut the gate valve and turn on the blower. To submerge, I will open the bypass to allow the water to push the air back out of the barrels.

I have got a lot of excellent input from everyone. I think this will work. I will give an update when I get a chance to build this thing. It will be a few weeks as I am working out of town and won't be home until mid June.

If anyone else has any comment/advice please speak up! Thanks everyone who contributed.

 

[UncleWillie]

Re: 55 Gallon poly drum lift

+1 ^^^

It takes ZERO pressure to blow bubbles at the surface. Take a straw and a coke and see how hard that is!
15 PSI (14.7) will displace air down to 34 feet. One PSI displace 27 inches of water.
You should be able to just barely blow out the bottom of a piece of pipe 4 feet long with a good health set of lungs. (~2-3 psi)
But you only need to blow air into the top of the tank so in reality 5 psi will get you safely started if you are less than 5 feet down.

One other thing to consider in the design is that 550 gallons will support 4500# only as long as they are displacing the water.
As soon as the barrels start to break the surface, the displaced volume is reduced.
Plan the design such that the barrels are just barely break the surface at their upper most position.
Think Submarine, not Pontoons, unless of course, you only need to lift 2000#

Until you reach the point of overinflation, No air will be lost out the bottom holes.

 

[smokeonthewater]

Re: 55 Gallon poly drum lift

ALSO keep in mind that if each barrel has it's own water hole, the assembly will need to be held level mechanically throughout it's range of motion.


If it were free floating you could sink it by simply stepping on one corner and letting all the air out the other corner.

 

[jdlough]

Re: 55 Gallon poly drum lift

ALSO keep in mind that if each barrel has it's own water hole, the assembly will need to be held level mechanically throughout it's range of motion.


If it were free floating you could sink it by simply stepping on one corner and letting all the air out the other corner.

Hmmmm. And if all the tanks were plumbed to the manifold so they could all be filled simultaneously from the same source, that means that all the tanks in effect would really be plumbed together, so air and/or water could shift from one tank to another. This is a problem. With any imbalance (stepping on one corner) air would move over to the opposite corner, and would keep doing so until the lift tilted completely vertically. If I'm picturing the manifold/plumbing set up correctly.

I think we're gonna need some diagrams...

 

[mavryk]

Re: 55 Gallon poly drum lift

Hmmmm. And if all the tanks were plumbed to the manifold so they could all be filled simultaneously from the same source, that means that all the tanks in effect would really be plumbed together, so air and/or water could shift from one tank to another. This is a problem. With any imbalance (stepping on one corner) air would move over to the opposite corner, and would keep doing so until the lift tilted completely vertically. If I'm picturing the manifold/plumbing set up correctly.

I think we're gonna need some diagrams...

I see what you're saying. Perhaps each barrel will need it's own check valve...... The lift will be mechanically held together with a steel framework. Each corner will have a ring that is able to slide up and down a post that is anchored in the riverbottom. This will allow the lift to be solidly anchored while still allowing it to ride up and down with changing water levels. This will also help to address the problems you noted about having an imbalance in the filling of the barrels.

I will try and get some drawings made and posted.

Excellent points. Thanks everyone for your input!