Pneumatic Jetski Lift (shop Vac Operated)

In this instructable, I will instruct on how to build a pneumatic Jetski lift. That is a lift that can be operated (remotely) with a simple lever and a Shop Vac.

Open the lever and the lift will gradually drop, press the remote and a shop vac will lift it up again.

All of this with not much more than some lumber, some barrels, PVC, and garden hoses (oh and a Shop Vac that can blow air). Except for the Dock Hinges that hold the lift in place, most materials are available at your local hardware store (and possibly eBay or FB marketplace).

How does it work? Well, a regular 55 gallon fully sealed barrel has buoyancy of about 416.35 lbs. Since these barrels won't be fully sealed they will carry a little less but two barrels easily carry most if not any of the jetski's out there. Mine lifts the jetski with me on top without issue.

Each barrel has two caps (most sealed barrels are configured that like). Once the barrel is on it's side one tap (top one) lets out air and the other tap (at the bottom) takes in air.

The "air out" hose is connected to a simple ball valve (turns out to be airtight)

The "air in" hose is connected to the bottom cap, with a pipe connected, that goes to the back/bottom of the barrel. When air comes in, it will want to go up and displace the water, present, through a large (4inch) hole at the back bottom of each barrel.

Many Shop Vacs available on the market allow you to connect to hose to the suction end but also to the exhaust (blowing) end. You'll need one that can blow. My 3.5hp Shop Vac has no problem pushing the air to the bottom of the barrels.

In the next steps I'll show you what materials and tools you need and how to construct the lift. Most of it is extremely straight forward but my first attempt did end up leaking air so pay attention.

Here is a quick demo of what I designed and built:

The entire project was first designed in Fusion 360. All graphics came from Fusion 360.

The Plastic barrels, were designed by the_Natrix 55 USG Closed Top Plastic Drum | 3D CAD Model Library | GrabCAD

Jetski was designed by Jonathan Globerson Waveblaster Jetski | 3D CAD Model Library | GrabCAD

Disclaimer, the links to amazon are affiliate links

Barrels:

You're best bet is to get these locally from Facebook market place. At any given time you'll find some available ranging from $5 to 20$ per barrel. Make sure you get the Sealed (closed top) barrels with the 2 screw caps. Also make sure to get the barrels for which each cap has the garden hose threading present (I think all might have these).

for reference: Plastic Drum - 55 Gallon, Closed Top S-10757 - Uline

For Lumber, I used plain pressure treated 2x8 from Homedepot

2x8x8 (x6) for raft and "anchor" (I happened to use 10' for my anchor as I intend to add a second lift)

2x6x6 (x2) for jetski rail (this may differ depending on the contour of your jetski's bottom)

Pneumatic parts (you know air in/air out)

Garden hose 4 ft (x4) Homedepot

Garden hose 10ft (1x) Homedepot

Garden hose Repair Connector Kit (needed for air tight connections) Amazon

Female Thread Garden Hose to pipe fitting (x3) Amazon

Male Thread Garden Hose to pipe fitting (x4) Amazon

PVC Pipe 2" 2 ft. (x3) Homedepot

PVC Pipe 1/2" 2ft. (x4) Homedepot

PVC Tee 1/2" (x1) Homedepot

PVC Tee 2" (x1) Homedepot

PVC Tee 2x2x1/2 (reducing from 2" to 1/2") McMaster Carr

PVC SxS Coupling 2" (x1) Homedepot

PVC SxS Coupling 1/2" (x2) Homedepot

PVC Socket CAP 2" (x2) Homedepot

PVC Elbow 1/2" (x2) Homedepot

PVC Ball valve 1/2" Homedepot

J-Hook 2" (x2) Homedepot

PVC Cement Homedepot

Silicone Marine grade sealant Amazon

Hardware

#9 x 2-1/2 in. Star Flat-Head Wood Deck Screw Homedepot

2 in. x 1-1/2 in. x 2-3/4 in. Galvanized Angle (x12) Homedepot

7 in. 16-Gauge ZMAX Galvanized Reinforcing L Angle (x8) Homedepot

#8 x 1-1/4 in. #2 Phillips, Wafer-Head Wood Screw Homedepot

3/8 in.-16 x 2-1/2 in. Zinc Plated Carriage Bolt (x4) Homedepot

3/8 in.-16 Zinc Plated Hex Nut (x4) Homedepot

3/8 in. Zinc-Plated Flat Washer (x4) Homedepot

Floating Dock Hinge, 3-1/2''x5''x3/16' (x2) ebay.com

Shop vac 3.5hp minimal (it works for me): make sure it has an exhaust AND that allows for connecting the hose. Homedepot has them but you stand a good chance of finding one cheaper on FB market place

Building the raft is very straight forward.

• Cut to 8 foot 2x8 board (x3)
• Cut to 4 foot 2x8 board (x5)
• Cut the anchor to the length that best suites your situation. My anchor is bolted to to posts that are 9 foot apart so I cut my board accordingly (I also want to add a second raft down the line.

before assembling the raft, it may be easier to first connect the dock hinges to the end board of the raft and the anchor.

Connect one half of each dock hinge about 2 inches from each corner to board 4. (Do not put them to the center too much. they will carry your weight as you walk on the edges of the lift)

• Drill the 4 holes through board 4 and use the carriage bolt washer and nut to connect the dock hinge.

Connect the other halves of the Dock hinges to the Anchor board. Make sure the position exactly to the hinges on the raft (you could use the drilled holes in the raft board as reference.

• Drill the 4 holes through board 5 and use the carriage bolt washer and nut to connect the dock hinge.

assemble the raft as seen in image:

I used 2 2-1/2 in. Star Flat-Head Wood Deck Screws at each meeting of the board and added corner brackets in each of the 8ft corners.

Board 1 needs to be over the barrel and can me moved a few inches from the end of the raft (mine is 4").

Board 2 needs to be at the edge of where the top of the barrel will be ~36.5" from end of raft (this allows to add something to stop the barrel from sliding).

Board 3 placement will depend on how long the rail for your jetski will be. Keep in mind the front of your jetski will not lean on anything as it tapers upward. I have board 3 about 62 inches from back of raft.

The "Air Out" assembly is the one that needs to be absolutely airtight. When the jetski sits on the lift, the air in the barrels will be pressurized and will try to find a way out. Initially I had my 4ft garden hoses connected using the original hose connectors. Those proved to be NOT air tight. This is why I added the hose repair connectors which can be crimped using the metal clams they come with.

Like I stated in the materials step, when you purchase the barrels make sure they are "closed top" and that each of the plugs has the garden hose threading present (3/4 NPS).

• Drill a hole (starting with 3/8 inch drill or use a Step drill bit) and take out till at least 1/2inch hole through the cap.
• Add a ribbon of marine grade silicone on the remaining edge inside the cap.
• Screw in the Hose repair connector (male).

Make sure there's a tight connection but at the same time be careful not to damage any of the large threading on the outside of the cap (it too needs to seal airtight).

Do not connect the hose until you've tightened the cap back into the the barrel.

There are tools for tightening the barrel caps back in the barrel but I ended up improvising my own tool that did the trick (made from 2" aluminum angle, readily available at home depot).

Next we assemble the "Air Out" Fork that joins the airflow of both barrels into one.

• Cut 2 pieces of 1/2inch PVC pipe at 4.5 inch.
• Cut 3 pieces of 1/2inch PVC pipe at 2 inch.
• Cut 1 piece of 1/2inch PVC pipe at 10 inch.
• Using the PVC cement glue together the pieces as seen in the image above. Let the glue dry for 24 hours before tightly connecting the male and female Hose repair connectors.

The 4 foot hoses go between the fork and the barrels, the 10 foot hose goes between the fork and the Ball Valve.

Do not connect the 4 foot hoses to the barrels yet. They first need to be installed under the raft.

The Air in assembly is less prone to air leaks as air will stop flowing as soom as the end of the "Air in" tubes go underwater; in effect sealing off any air flow.

I use 2 inch PVC that splits off into 2 1/2inch tubes. Technically it would be better to split off into 2 3/4inch pipes (or even 1 inch pipes) but I was not able to find the hose connectors that could connect to those.

Unlike the "Air out" Cap on the barrel, the cap for the "Air Out" is not screwed in using a hose repair connector. Instead, I "extend" the hose in with with a PVC pipe that reaches further to the bottom of the barrel. This is done so the back flow of air "opportunity" sits lower than the cap and will seal as the barrel goes down a little.

For the "Air In" caps of each barrel:

• Drill out the center to 0.84 inch diameter which should fir the 1/2inch pipe.
• Cut a 1.1 inch segments of 1/2 inch PVC pipe.
• Using PVC cement glue one end of the 1.1inch pipe into Female PVC Garden Hose connector.
• Insert the glued in PVC pipe through the Cap Feel free to put a big dab of silicone into the cap.
• Using PVC cement glue the 1/2inch SxS Coupling to the PVC segment that came through the cap.
• I inserted the entire piece between a VICE to clamp it all together and let is sit for 24 hours.
• To top it off you can add silicone around the SxS coupling where it meets the cap.

Once the cap "assemblies" are done glue in 24inch 1/2inch pipes into the SxS Coupling.

Insert the CAPs into the barrel but do not connect the hose yet.

Next we assemble "the Air In" fork that splits the single airflow in, to each of the barrels. In real life pictures of my lift you'll see that my Air In setup is narrower than the one we're putting together here. Because mine was shorter I had no other way to attach it, than to add some more boards to the frame. By making it wider it will meet the outer boards of the raft and the assembly can be connected to those using PVC J-Hooks.

• Cut 4 pieces of 2" PVC at 11 inch.
• Cut 1 Piece of 2" PVC at 5 inch.
• Cut 2 pieces of 1/2inch PVC pipe at 2 inch.
• Using PVC cement glue together the piece as seen in the image above.
• Attach the hose repair connectors to the assembly.

As non-intuitive as it sounds, now is the time to start drilling some holes into the barrels. Each barrel will have a large hole (using a 3.5" Hole saw bit) and two smaller holes (explain in a bit).

The holes are needed to displace the water as the shop vac pushes air in to the barrels. The holes will be at the lowest point in the water so no air will escape.

• Drill a hole about 2 inches from the bottom of the barrel to allow for water displacement.
• Drill 2 smaller holes (that can fit a zip tie) high enough to be opposite of the "Air In" PVC pipes
• Tie a Zip tie around the PVC pipe inside the barrel and pull is closer to the wall (careful not to break the seal in the cap.

The close the exit of the PVC pipe sits to the wall of the barrel the more air will be captured for flotation. You could skip the last step as these barrels can float much more than most jetski's weigh.

READ THIS BEFORE DRILLING!!!!! The barrels I purchased had two caps on the top but each cap had a different thread. MAKE SURE that you drill the holes on the side of the barrel where the "Air In" cap is installed. If you accidently drill on the wrong side the CAP threads may not match and you'll have waisted the entire barrel.

At this point all the components are in place and you're ready to assemble and install the lift.

Put the barrels underneath the raft and use straps or ropes to keep in in place. Once floating they'll stay in place but while moving on land the like to move.

Connect the hoses using the metal clamps that came in the Hose repair kit. "Air In" goes to the bottom CAPS "Air out" goes to the top CAPS.

Connect the "Air In" assembly to the outside raft board using the PVC J-Hooks. You can leave a little slack in the hoses but don't put it too close to the barrels. You Jetski could damage it.

Use some zip ties to connect the "Air Out" assembly to the "Air In" assembly.

I designed a connector to connect the Shop Vac hose to the "Air in" Assembly but I'm afraid most hoses are not created equal. Add some blue tape around the Shop Vac Hose to create a decent seal between the PVC and the Shop Vac hose. Possibly use some metal wire to keep the two together. The ridge of the SxS Coupling and ridges in the hose will allow for that.

Like I stated in the intro. The Raft Anchor in my setup is bolted into the post of my Dock. I do not know what your connection possibilities are. They could be similar posts. You could also consider putting some metals posts in the water and connecting the raft to it. If you've made it this far, I'm sure you can figure something out.

Make sure you don't install the to high. Mine has the bottom of the raft (at the dock side) about 4 inches above water surface which creates a good angle for the jetski to sit and even ride onto the lift (without sliding back).

Once the Anchor is installed you can simply attach the raft/lift with the PINs in each Dock Hinge.

Be careful when moving the raft into the water not to drop or snag the hoses on any sharp angles to could break the connection to the barrel.

as an upgrade, I purchased remote switch that allows me to turn on the shop vac while on the ski. This way I can ride it onto the lift and raise it with me on it.

And there you have it. Enjoy the season!!