I don't have a great picture right now, but I'll try and describe how we do it:
- ensure the aft end of the tube closest to your vessel's stern is positioned inside the davit support (in your picture you have it on the outside); this is very important to stop any side to side movement of the dinghy.
- using adjustable tie-down straps, we bring the dingy as close in to structure of the davit system as possible, with the inside tube snug up against the back of the seat structure; the hooks of the tie straps are hooked into the dinghy's lifting eyes (inside at the stern; outside at the bow), with the strap wrapped around the davit system's lower horizontal bar (i.e. the one that supports the front of the seat).
- we use one ten foot strap on the stern, and two six foot straps at the bow.
- if we are anticipating particularly rough conditions we will add two more tie straps cross-wise, one from the dinghy's inside stern eye to the port (opposite) side of the davit structure, and one from the inside bow eye to the starboard side of the structure.
With the straps securely fastened we have no concerns about the security of the dingy or davit system. This arrangement has served us well and without incident over thousands of miles and in all sea conditions.
If you would like I can take a couple of pictures when I'm next at the boat and send them to you.