WaterWalker from used utility poles and big buoys
November 6, 2008 at 8:13 pm #735
After several calls I finally found out that used utility poles cost $2/foot in Anguilla. I will go by tomorrow to see what they have. If I could get 3 poles of 40 feet each I would be very happy. For about $1,200 I could buy 3 huge buoys to tie to the corners of the tripod to make a very large WaterWalker. Anyone willing to contribute to such a project? You can just post a pledge now and only pay with paypal after I have results, pictures, and video published.
— VinceNovember 6, 2008 at 8:47 pm #4181
How long are the telephone poles. By my math, a 50 ft telephone pole should weigh in at about 1100 lbs. If the buoy only has 1345lb of buoyancy, you only have 245lbs of excess buoyancy per buoy.
How are you going to move the telephone poles around? Also, how are you going to move the assembled walker around? On land it will take a small army. In the water it will be very challenging.
Those truss beams you found looked lighter (but more expensive.)
Maybe you can find some cheaper buoyancy. Maybe some polypropolene [sp?] drums, or even metal drums. Maybe you can visit the local rum factory and bum some empty rum drums. (Free poetry!)
I’m just trying to think of problems before the money is spent.November 7, 2008 at 2:41 am #4182
>How long are the telephone poles. By my math, a 50 ft telephone pole should weigh in at about 1100 lbs.
> If the buoy only has 1345lb of buoyancy, you only have 245lbs of excess buoyancy per buoy.
Well, I am hoping for the thinner “class 5” or “class 6” poles but will know tomorrow what the current inventory of used poles is (class weights in URL below). Also, I am looking at 30 or 40 feet in wood poles and not the 50 feet I would do with aluminum truss legs. But yes, these kinds of numbers must work out before we build/launch it or it would be really embarrassing.
>How are you going to move the telephone poles around? Also, how are you going to move the assembled walker around?
>On land it will take a small army. In the water it will be very challenging.
There are many flatbed trucks here with cranes on them. So moving and setting up could be done with these. They can drive down the pier I use and lift it from the truck into the water. I might leave it setup in the water and just tow it back to my mooring with my boat after a kite-pulled ride. Eventually I would come back to the pier and use the truck to take it out. Not sure how bad the wind on this will be or just how much my boat can pull. Probably the last 10 feet of the poles are under water and the rest is at a 45 degree angle, so it does not seem like the wind resistance will be that great. I think my boat will be fine. Can have anchors and sea anchors on the seastead and a bigger boat lined up to help out if I get into trouble.
>Those truss beams you found looked lighter (but more expensive.)
Yup. The 40 feet in aluminum truss is only 140 lbs, far less than the utility pole. But 3 legs of 40 feet each totals $240 in used utility poles and $4,356 in nice aluminum truss beams (plus non-trivial shipping and duty). This savings can easily justify a crane truck for a few hours. Though the truss would be the way to go if there were a contest where the seastead had to fit in a pickup truck. And the lighter truss would let me carry more stuff. For a production seastead I think an aluminum truss is much better, but for an experiment/demonstration the wood utility poles are probably ok.
>Maybe you can find some cheaper buoyancy. Maybe some polypropolene [sp?] drums, or even metal drums.
> Maybe you can visit the local rum factory and bum some empty rum drums. (Free poetry!)
Maybe. I will call Anguilla Rums and see. I suspect these buoys can be used again and again for seasteading stuff, so it may not be too bad to buy them. These buoys are designed to handle the 1,300 lbs buoyancy with the dynamic ocean making for even more force than that sometimes, so I would trust them to work. Also, I ordered some small buoys so I will be able to build a 1:25 scale model that works as a 1:10 scale model for the 1:2.5 scale model before I build it. The leg sizes being 4 feet, 40 feet, and 100 feet for full scale. I want to be very sure before I tell my friends, “It will stay together at least for 1 day, come onboard”. Don’t want to have to tie some drums together so I can pull on them with 1,000+ lbs whle in a moving ocean all day (or maybe longer) without leaks or ropes coming loose. I really want to be able to park it at my mooring in the harbor and take it out several times during a month. So I want it to last at least a month. Sometimes it is better to spend a little money to have something reliable.
I think I will make a net platform and use some palm leaves for a roof so we have some shade. This should make it look nice enough that I can leave it in the harbor for 1 month without getting into too much trouble.
Also, this model with 40 foot legs should be as similar as possible to the final 100 foot leg design so that it is an accurate model. The wave forces on a smooth round buoy are different than a group of barrels tied together. My current plan is for the full scale one to have something shaped like an inflatable buoy but filled with foam. So this buoy makes for an accurate model.
>I’m just trying to think of problems before the money is spent.
Yes. That is the best way. Part of why I posted before I bought some poles.
— VinceNovember 7, 2008 at 3:10 am #4189
We have empty land to build this model on. With a platform and thatched roof it would be like a tree fort for my boys to play in. So even if we did not launch it the $240 for the poles would not be wasted. I have a backhoe and think that I can lift the model up into shape. I will lift the center, brace that. Then put rocks behind two legs and lift/push in the 3rd leg with the backhoe. We say my backhoe “Faith” can move mountains, so this should not be too much for it.
Then if I get the big buoys, or some other flotation, a crane can just pick it up, lay it on the truck and go to the pier. There we attach the buoys and it lowers it into the water.
If they have some poles that will work for me I think I will get them tomorrow.November 7, 2008 at 3:20 pm #4191
There were 9 used utility poles. Of these 8 are “class 3″ and 40 feet long. So they are kind of heavy. Might make it work with 30 feet though. There are thinner poles on the island just not as many and no used ones at the moment.
I went by the hardware store and they have some 3″ galvanized pipe that is 20 feet long. This is far lighter and 2/3rds the length. It has these threaded pieces for joining two pipes together that would be nice and strong for attaching ropes or wire to the ends. I may even be able to load it on top of my explorer. No need for a crane truck, maybe a pickup. This would be a 1:5 scale model, which always seemed like a good next step. For sure my boat could pull it. The pipes are $161 each, but I could save some by getting smaller buoys. The A-6 buoy with about 800 lbs buoyancy at $285 each is probably good. So main costs are 3*(161+285)=$1,338.
There is also 3” square tubing at 20 feet long. It does not have threads and a nice strong thing to put on the ends, so I am not sure how I would attach to it. But it is cheaper at $53 each.
Anyway, maybe 1:5 scale is the right size to try next. Could still hold 2 people and be plenty stable enough for the ocean near me.
— VinceNovember 7, 2008 at 4:58 pm #4192
Actually making a working, scale-prototype seastead. Vince… you so totally rock.November 7, 2008 at 7:40 pm #4193
You can probably drill holes in the square tubes for attachment purposes.
The stresses on these pipes and tubes are going to be enormous. What may seem completely rigid to you may bend like a wet noodle under the stress involved.
If you have any animal feed stores on the island, you might be able to find a reasonable sized plastic drum for buoyancy instead of the A-6 buoys. 3 × 800 lbs of buoyancy is 2400 lbs, which is probably overkill. So checking around might make some sense. Some exercise balls are about the same size as they A-6 and should be significantly cheaper.
I’m just throwing out ideas to try and help get the price down.November 7, 2008 at 8:49 pm #4194
The concrete plant close to me gets their retarder (slows the drying process) in 54 gallon plastic drums. They have 150 available and more coming in. They sell for $20 each. I was able to fit 3 in my Explorer and now have them in my yard.
I think if I put a 3″ by 3″ section of wood into the ends of the square tubing and have several bolts through this I can make something strong enough to attach the ropes to. I really worried that the thin metal would tare or cut the rope.
That I can fit the floats inside and the beams on top of my Explorer makes transportation very easy. I can drive to an upwind location and get picked up at a downwind location.
So the main cost for 3 floats of about 430 lbs buoyancy each and 3 beams of 20 foot each is $219. I can still take one other person on with me. No need for pledges or sponsors. I will need some ropes and a few other things but this is a very affordable project all the sudden. Cool.
— VinceNovember 7, 2008 at 8:57 pm #4195
Agree with Thorizan, you rock big time!November 7, 2008 at 9:26 pm #4196
Good idea checking out the cement factory! I knew there had to be plastic drums collecting somewhere on the island.
Have you thought about how to join the three tubes at the apex of the tetrahedron? With the square tubbing, it should be possible to easily get all three tubes so that they are 90 degrees orthogonal to one another. With enough bolts going through the wood ends it should be strong enough.
Have you thought about how are you going to attach the drums to the beam ends yet?November 7, 2008 at 10:31 pm #4197
>Have you thought about how to join the three tubes at the apex of the tetrahedron? With the
> square tubbing, it should be possible to easily get all three tubes so that they are 90 degrees orthogonal
> to one another. With enough bolts going through the wood ends it should be strong enough.
I think that if the joint can not flex then I have a good chance of breaking something. Thinking of some foam between the wood pieces and then ropes between the wood and the platform attached to those ropes. Not sure yet and could easily change plans,
>Have you thought about how are you going to attach the drums to the beam ends yet?
The float will be tied to the wood in the end of the square tubing. Question is just how to tie to the float/drum.
There is a lip around the edge that might be strong enough to attach to. If not then a net or set of ropes over it.
Can test it by filling the drum with water and lifting with the backhoe.
— VinceNovember 8, 2008 at 3:05 pm #4201
LOL I just posted about Assurance contracts as a way to fund public goods or even a seastead, and Vince’s funding model: pledge now and pay only if I actually complete, is very much an Assurance contract:
BTW, compressed air as energy storage is being used by electric energy utilities for load levelling or time shifting of renewable energy:
I assume they’re using concrete-lined old mines. So the concept seems to have some precedent and practical expression. Energy efficiency is about 50%.November 8, 2008 at 5:21 pm #4202
Took a couple pictures of the parts, weighed them, and started a wiki page:November 8, 2008 at 7:54 pm #4205
Did some tests with weight on the middle of the beams with the ends supported. They are very strong. Since the WaterWalker design is a tensegrity design it will never put forces on like this. So I think they are plenty strong enough. There are 20 foot 4x4s on the island that could work as well. They are heavier though so I may stick with the steel even though it is a bit more trouble and money.
–VinceNovember 9, 2008 at 10:58 pm #4213
Would not a circular tube be more efficient for a pure compression part?
Also, have you looked at aluminium instead of steel? It could perhaps be more optimized due to the fact that it´s light and metals are prized by weight. Sure you will need more of it (thicker walls or larger diameter), but it could still be cheaper for the same load capacity. And with compression loads, thicker walls are a good thing (makes it harder to buckle).
Also you don´t have to paint aluminium. This saves a boat load of work. Rust proofing the inside of a pipe is difficult, for obvious reasons. I realize this is experimental stuff so longevity might not be needed, but it still might be good to start getting experience with the most suited materials for the job.
Welding is usually harder with aluminium so this might be a downside.
The forum ‘Structure Designs’ is closed to new topics and replies.
Posted on at