The buoy, where I put the support?

Excuse me, I want to plead for help again.

I have already finished the geometry shape of the buoys on Staad Pro. Buoy is an object made of plates and serve like a buoy, buoy used as a mediator between the ship was about to stop in the middle of the ocean with the anchor.

Dimension diameter buoy is 3meter, 2 meters long, and has a cross inside. By the time you put a buoy on the ocean, the buoy will float with long 1.75meter buoy will sink.

I am confused about "where I have to put support?". and "I have to wear support what? pin support or fixed support or support but combinations (pin and fixed but)"
Support should be put in a position, in order to remain stable despite buoy buffeted by the waves of the sea.

In mechanical science technique, buoy got:
> Force of the anchor (assumed: Force in the -X direction of the resultant XY on Staad Pro)
> Force of ocean waves (we assume: Force in the X direction on Staad Pro).
> Tension Force of the ship (note: the buoy is also connected to the vessel through a chain; assumed: Force on the X direction on Staad Pro).

I want to thank you for your attention.

Best Regards.

Cathalyst