DIY Sanford and Son Boat Lift

Arklie,
Nice work and engineering! What did you use for a compressed air source?

Nice work! This looks/works exactly like our Hydrohoist. Lift/lower times on ours is probably 2-3 minutes. I think early models lowered a lot slower but they started adding a bypass valve that lets air escape without running back through the blower.

The decent depth is controlled by the length of chains mounted on the rear corners. As far as the speed of the decent and ascent, it is purely controlled by the size of the gas valves. Speed could be further dialed in by enlarging the holes in the bottom of each barrel, e.g., larger holes may increase the speed up and down, since water and air could be displaced more quickly. I assume the speed of lifting could be increased by a stronger air pump.

As Craig mentions relative to his Hydro-Hoist, I also have 2 valves. One is placed immediately next to the air pump, between the air pump and the lift, the other is mounted on a tee between the first valve and the lift. I will take a picture of it next time I am at the lake. For now, see the caveman sketch below, apologies to union plumbers and real engineers. You can get a faster launch if both valves are open, but sometimes water can back-feed into the blower canister, which is not a good thing. Obviously, the valve mounted adjacent to the blower should only be opened when lifting. The other valve only opened for lowering.

It only takes 3 or 4 minutes to launch or retrieve, I would like for it to be faster but the slower speed allows me more control in making sure the boat is centered. A faster speed might be more dangerous for inexperienced users.

Typically the lift is lowered to launch the SN and if left in the down position all day and lifted at the end of the day when the fun is over. If the lift is raised without a boat on it, then yes, it will take much longer to lower the lift the next time since there is considerably less weight forcing it down.

can I ask how much your boat weighs that you use this DIY lift for? I'm about to try the same type thing and have a 2200Lb dry weight triple Pontoon! Any certain style fittings you used to fit the barrels bungholes? and any certain placement of the drums? Thanks so much for the help, and Looks Great! I hope mine works out the same!

Thanks for the reply! I will take all of your info into careful consideration! So you are saying you used the 3/4" center threaded area on the one bung? And just drilled out the flat area in the center of it? Will that or does that allow enough air in and out fast enough? Also.. are those Plastic bungs strong enough to withstand the pressure? Id assume so.. being they carry and contain heavier weights when full of liquids...
You said you used a 1" garden hose for air? How does that hold up? I was planning on using this rubberized poly hose the local hardware store has in stock.. I believe its one inch inside diameter.. but would be going down to a 3/4 inlet adapter into the bung.. sound ok?
I was originally planning on 8,   55 gallon drums.. but may go with 10 to be safe.. finally my biggest question.. as my scientific mind is going nuts about it.. haha but What size hole did you drill in bottom of drums for water release/inlet? And did you drill holes in all drums? My thought was that if the air forced water out of the highest drums in the set, that they would just blow bubbles while the ones further back and down in the set would still be pretty laiden with water.. do i drill holes in all? Or just in back ones? Finally.. My brother in law is in Construction and says he would use Unistrut for ease if building the frame... sound sufficent enough? Its pretty strong stuff! Ill try and post pics when done!

It doesnt seem to be about pressure.. but rather volume.. not really pressurizing the drum other than to push the water out of the drain hole.. ive seen the big company or manufacturers Lifts.. their expensive poly tubes or floats use this same science of displacement. The way I see it.. These poly drums hold im some heavy heavy fluids and gels or soaps etc etc.. if the fittings hold that while being bumped, rolled, dropped and banged around.. they shoukd easily hold even a little air pressure haha.. I hope..

Hi Joe,
I'll try my best to answer your questions. Here is a typical closure plug. Make sure your barrels have these type of plugs. As I said earlier, you may encounter trouble finding the correct ones after the fact; my experience is that each manufacturer has their own thread and overall diameter.



As you can see, the center of the plug is threaded for 3/4" NPT. Simply drill out the center and tread in your adaptor. Each barrel typically has to bungholes. You need one of these plugs for each barrel. And you need one that hasn't been drilled out for the other bunghole. I used teflon tape to seal the treads on both bungholes plugs and the threaded adaptor(s). As you can see in the pictures of my lift, you will need to orient the barrels so that the plug with the pipe adaptor is at the 12 o'clock position.

I used a commercial garden hose to plumb all the barrels together, because I'm cheap. A commercial garden hose is typically long enough to provide all the hose you need at a minimal cost, and they are typically quite UV resistant. I have no experience with the hose you mention, but my guess is that it is expensive and not very uv resistant. It might work, though.

Relative to the holes drilled in the bottom side each barrel. I used a 2" hole saw, as I remember. Each barrel must be drilled, because if you don't there will not be a way for the water to be pushed out by the air. Same thing for lowering, there must be a way for water to enter each vessel. The size of the hole will be one of the controlling factors on lowering and lifting speed and control. You are right about the barrels near the front of the lift blowing out air before the rear ones. It is expected since the rear barrels are doing the heavy lifting since the front barrels are nearer the pivot point. No big deal, don't worry about that at all.

Relative to the Unistrut or kindorf. I have only experience with the typical type used by electrical contractors. Maybe your BIL has some heavy-duty stuff in mind? I build stuff to last and would never consider using that stuff to build something like this. That's my opinion, and I would not want to offend you in any manner. I think that stuff is basically a toy. When you use the lift for the first time you will be amazed how much force the lift has to endure to pick the boat up. My guess it that to obtain the rigidity you ultimately need to prevent the lift from bending double you would need to use a lot of that stuff sam witched together in some configuration. Then think about wake wash from the lake, winter weather, storms, etc. To use substitute structural steel for the Unistrut is not going to add much to the cost, and may in fact be less expensive. The Unistrut Ive seen has a wall profile of about 1/8", it will not last under this type of stress.

Finally, Pete is wise. I use a vacuum cleaner motor to provide the air. I am not an engineer, but I think a typical shopvac probably only generates a few PSI of pressure out the exhaust, You don't need a lot of PSI, only a lot of volume. One of those cheap shopvacs that the box stores basically sell as a door buster on Black Friday for $29 will work fine.

shierh wrote: Wouldn't the pressure in the barrel increase with weight pushing it under water when it is filled with air?   .

Yes, the pressure will increase as the water is displaced by the air but only to the depth the barrel is pushed under water. IE: if you push the barrel 18 inches under water, the pressure in the barrel will be 18" water column. For those that prefer pressure in PSI, 18" of water column is .0.650291252 PSI

Nice edit job on the conversion tp PSI Pete.

You must have done the first one on your abacus and then decided to go to onlineconversion.com or one of those sites to get it right

Much appreciated! Cant wait to get started! I will definitely look further into the materials to use.. I heard great things about the unistrut! Saw tests of it holding up to over 2000 lbs of force bouncung and pulling on one spot.. so when all bolted together and working in unison.. its pretty strong stuff.. they also make a double width section.. loiks like a 2x6 box steel tube. Was planning on using that for main beams.. some of the hydro hoist models seem to use very thin materials... no clue how they hold up so well...

does it make a difference if the container is not that rigid and may deform some?   

8122pbrainard wrote: shierh wrote: does it make a difference if the container is not that rigid and may deform some?    The tires on your car deform some but they still hold the car up!

Case in point Pete
tire deformation

shierh wrote: guess only way to increase the pressure is to completely submerge thereby reducing the actual size of the container,

To increase lift, the volume of the container(s) must be increased. Lift is determined by the displacement of the weight of the water. A cubic foot of water is about 62.5 lbs. There are about 7.5 gallons in a cubic foot.

KENO wrote: Duane, you're just so predictable, I had a really good idea what I'd see when I clicked on your link

Comes from too many years of working on Nitro cars and smelling the fumes

shierh wrote: I meant completely submerge a container that was full of air. deeper you go the smaller the container would get and an increase in pressure.

Yes, the deeper you go, the more pressure is needed inside but, that doesn't increase the lift. Think of a sub submerged just below the surface and then 100 feet below the surface. It's buoyancy is the same at both depths.