Im 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 made this model to show how the semi-submersible rig main principles works.

A semi-submersible rig is often preferred over a vessel (boat) because of its stability. It all lies in the pontoons, where the rig gets most of its bouyancy from, is submerged. And there is only four feets sticking up of the water. This will decrease the area affected by waves drastically compared to a vessel. And makes the rig more stabile in rough weather.

It is important for the rig to lie level in the water. Because of different equipment on different places, the rig will have an weight imbalance. The rig has big tanks in the hull. These are filled or draind 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 it and try it on the water.
The CG will probably be way of. You need to ballast the rig. Put in, or take out coins from the tanks in the hull to make it lie level on the water. You need to lift off the main and lower deck to acces the ballast tanks.
It is also possible to put coins in the lowerdeck.
*Unfortunately the cointainers makes the rig to top heavy and can not be used. I will leave them in the files in case some one want to try it anyway

Experiment on how you can make the coin rig as stabile as you can get. How much can you put in, and where should you place it?

The crane, upper tourch, lifeboats and helideck is not neccesary. 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 main and lower deck. Without the purpose of attaching helideck, the tourch, cranes or lifeboats.

UPDATE 08.07.15
I`ve added a coinslots to easier accsess the ballast tanks. You only need to lift of lower and main deck to get coins out.

UPDATE 16.07.15
I am not happy with how much bouyancy the pontoon gives, and are working on a new version.

The life boats are too small for being usefull. I will not remove them, incase someone wants use it for show.

UPDATE 17.07.15
I`ve added a new pontoon with more bouancy.

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