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Ferrocement sphere

Home Forums Research Engineering Ferrocement sphere

This topic contains 16 replies, has 6 voices, and was last updated by Profile photo of Elwar Elwar 3 years, 2 months ago.

Viewing 2 posts - 16 through 17 (of 17 total)
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  • #16611
    Profile photo of Elwar

    OCEANOPOLIS wrote:

    If your goal is to built a 10’x10′ small floating island, fill it up with sand and tow it to the sandbar, then using ferro spheres will be expensive compared to other methods of achiveing your goal. You will have to built 25 sphere of 2′ in diameter. Then, you will have to raft them up somehow. Then, you will have to build and secure the sandbox on top of it. Then you will have to buy a small boat to tow it to the chosen location. So far, you are looking at a good $5k+ and the labor, since you need at least a 20′-22′ LOA boat with a 100 HP outboard to tow your 10’x10′ island behind. (being of ferro, will be heavy)

    The easiest way out, is to buy a small used houseboat with a running engine for that money, and use it for your purpose. You will save on all that labor, plus you will have living amenities onboard (fresh water, a small galley with fridge, stove, a head, a small stateroom with a couch to get out of the elements when needed, a VHF radio, lifevests, flares in case of emergency, etc). The “sand beach” can be easily built on top of the cabin.

    Also, keep in mind that towing “anything” its a bitch, no matter what. Also, keep in mind that you will be required to register that island with the Florida State. Since it’s a “new boat construction”, the Coast Guard will have to inspect it DURING construction to give you a safe flotation ok. Now you opened a can of worms, my friend, since this guys are picky, picky, picky…I dealt with them for years,…

    Another way to save money and labor would be to built your island as one hull, on a 10’x10′ float, your choice of shape, out of marine plywood, and then just ferrocement the bottom and the topsides. Then do the towing thing. IMHO.

    A 10′ x 10′ small floating island is not the ultimate goal, it is an incremental goal. First goal is a single sphere floating, then three spheres linked together floating, then the small 10′ x 10′ island. From there I can expand incrementally. The 10′ x 10′ allows me to do testing of seaworthyness, ease of expansion, durability, cost, etc.

    The next step would be a small island large enough to have a small living quarter. Then get to the point where I can sell them and expand to the point where I can manufacture the spheres on the island.

    As for just buying a houseboat instead. I have already had boats. I had a deck boat that was fine for what my initial goal would be, having a place to hang out and swim or fish and sleep on at night. But there is no way to expand it. I could buy a bigger boat and just keep buying bigger boats, but what would be the point? Instead of seasteading we could just call it boating.

    Initially it would not be a boat, it would be something towed. Similar to those huge round rafts that kids ride on behind speed boats all day long. Once it gets big enough to the point where it will not fit in my canal, then I would need to go through the beaurocracy. Around my area just about anything that floats is fine. I have a buddy that has a floating dock with a motor with a picnic table and umbrella on it that he rides out to the sand bar. He has the proper life jackets, whistle, flares and radio. Good enough for this area. And my sea wall has enough room for a 10′ x 10′ dock, I think I calculated that I could have a 30′ wide dock being at the end of the canal.

    Profile photo of Elwar

    Ok, I have for the foreseeable future given up on this project, started breaking down the unfinished balls in my back yard and do not plan on moving forward with this. I will provide a lessons learned for this idea.


    The ultimate goal was to have an easy to make small component which would allow for incremental growth of an island which would allow you to actually make the island grow from the actual island. I chose spheres because of the strength that it would be able to hold against waves and for surface area.


    I will cut to the chase and describe how far I got. I was able to build 7 ferrocement spheres which could all float. I used nautical rope to connect three at a time, connecting each three to each other. The result was a hexagon with a single ball in the middle and six around the center ball. I had a Walmart pool that I was able to do a few wave tests on, it did appear that the front balls took the brunt of the wave and dissipated the wave by the time it got to the back balls. I was even able to sit (rather awkwardly) on the balls and they held my (~200lb) weight.


    My plan was to ramp it up with 30 more balls. I bought the materials and spent one hot Florida afternoon trying to build them all in an assembly line fashion. Unfortunately I believe that my technique was not the best and the cement was too thin and I ended up with a bunch of balls that were very brittle and not able to take more coats of cement before breaking apart.


    While I could have probably had 37 balls put together in a large hexagon form and had it floating in the Gulf of Mexico, life ended up getting in the way and an angry wife was not too pleased with a bunch of crumbling cement balls in the nice back yard.


    My technique for creating each ball was to buy a $2.50 Walmart bouncy ball, wrap it in mesh drywall tape and cover it in ferrocement. The last part is the most difficult. The first time I did it, I had fairly thick cement and I spread it on by hand with much cement clumping and falling off but after about an hour of work I had what was shown in my original picture. This ball was the heaviest but the strongest of all of the bunch, the thickness was probably close to an inch.


    My assembly line approach I used on the next 6 balls fairly successfully. Instead of a thick ferrocement mix, I watered it down a bit to where I could put the balls in the cement and roll it around until all of the tape was coated. I then allowed it to dry and continued to roll it in the cement later for several more coats. Ideally this would be done throughout one day but I took a few weeks doing coats here and there. The thickness was decent enough and the outer coating was a lot smoother. For these I used the mesh tape all over the ball, it is difficult because the tape does not stick and you have to keep globbing cemented tape around the ball.


    So I tried to do the same with the 30 balls. I did not have as much tape so I thought that if I did a criss-cross pattern on the ball it may hold the cement in between tape spots to hold and I had planned on doing several coats in one day so I figured that the cement would hold. This was not the case. It only held where the tape was and crumbled off everywhere else. Plus, after working through 30 balls in the hot sun, I was in no shape to continue putting on more coats and it was crumbling anyway so I was very frustrated.


    I did get pictures of the balls in the pool and some video but unfortunately the SD card in my phone died.


    This would be a good project for someone who wants to try to do something on the cheap but has some time on their hands. You can even pile all of the balls in your truck and drive to the water to test them.


    For the 37 ball hexagon I was looking at a cost of about $160 shooting for a price of close to $5 per ball.


    The beauty of it is that you can use the balls as a way of breaking the waves and the force would be distributed. A 10 foot wave would only need about 10 feet of balls to break up the wave with everything beyond that having very little motion. You could add balls underneath to add bouyancy but the balls each can hold around 50-100lbs.


    I would have loved to just set one of these up out in the Gulf near where I live and put some solar lights on it or reflectors so boaters could go out there and use it as a meeting spot and hang out. It would have been great for camping out on the water as well.


    I had ideas for an even sturdier ball with much more buoyancy and even a way of generating electricity by the movement between the balls but that would require a significant capital investment and I was only planning on pursuing such funding once my proof of concept had been finished.


    Hopefully someone else can take on this project and go with it.

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