The semi-submersible coin rig

thingiverse

I'm currently away and not able to print anything before I get home. If you print this and find some faults, please tell me and I will try to fix it. ## **Stl. drawing of the rig is for 3d viewing and is not printable!** **About** The semi-submersible coin rig is inspired by the Kristin platform. Kristin is a semi-submersible oil rig in the Norwegian sea. **The science** I created this model to show how the semi-submersible rig main principles work. A semi-submersible rig is often preferred over a vessel because of its stability. It all lies in the pontoons, where the rig gets most of its buoyancy from, is submerged. And there are only four feet sticking up out of the water. This will decrease the area affected by waves drastically compared to a vessel. And makes the rig more stable in rough weather. It's essential for the rig to lie level in the water. Because of different equipment on various places, the rig will have a weight imbalance. The rig has big tanks in the hull. These are filled or drained with sea water to compensate for the weight imbalance. To make the rig stable, the center of gravity (CG) needs to be in the middle, as low as possible. **Use** After printing out the rig assembly and trying it on the water, you'll probably find that the CG is way off. You need to ballast the rig by putting coins into or taking them out of the tanks in the hull to make it lie level on the water. You must lift off the main and lower deck to access the ballast tanks. It's also possible to put coins in the lower deck. Unfortunately, the coin containers make the rig too top-heavy, and they can't be used. I've left them in the files in case someone wants to try it anyway. Experiment on how you can make the coin rig as stable as you can get. How much can you put in, and where should you place it? The crane, upper torch, lifeboats, and helideck are not necessary. To save print time, you can exclude them. I made them just for fun. **Note** I've added several informative pictures. **UPDATE 07.07.15** I've added a plain version of the main and lower deck without the purpose of attaching the helideck, torch, cranes, or lifeboats. **UPDATE 08.07.15** I've added coin slots to make it easier to access the ballast tanks. You only need to lift off the lower and main deck to get coins out. **UPDATE 16.07.15** I'm not happy with how much buoyancy the pontoon gives, and I'm working on a new version. The lifeboats are too small for being useful. I won't remove them in case someone wants to use it for show. **UPDATE 17.07.15** I've added a new pontoon with more buoyancy. Made a video of the coin rig (https://youtu.be/MLpwNVyeALc). **Source**: Picture of Kristin platform - http://www.tu.no/migration_catalog/2006/04/25/kristin-plattformen0604251333.jpg/alternates/h1080/Kristin%20plattformen0604251333.jpg