New FC4 owner, rigging question

[coreyva]

I just dropped for a FC4. I've had a 9' outcast tube that works well, but wanted something for lakes and slower waters. I've been looking over the rigging pics, but am wondering if the homemade PVC creations are being attached to the bottom somehow as well. I see the two D-rings on the side, and I know there are a few on the bottom, but haven't seen anything attaching them to the bottom. Is this needed, do the racks flop around if not tied down? Just looking for some guidance before I head off to home depot.
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