Bracket for Stern Anchor

Dear SVB Team. Can you please tell me the diameter of the two cross bolts on this stern anchor support? Before I return to the boat, I need to procure or make a folding nose bolt.
I installed the two existing cross bolts so that the position of the support at the bottom and top matches my transom. The bottom position is approximately horizontal. The top position is such that the bracket with the anchor does not fall back down before the lines are secured.

Problem: When retrieving the anchor at a relatively steep angle upwards into the cockpit of the hawser chain, the support accidentally folds upwards before the anchor is in the roller. The support should be secured at the bottom with an additional, quick-locking cross bolt to prevent it from accidentally folding up. If the 150mm folding nose bolt isn't available, I'll fabricate stainless steel round stock of the appropriate diameter, with a threaded end face and a V4A countersunk washer on one side using a fillister head screw, and a removable cotter pin on the other side. Thank you for the information about the diameter of the cross bolts.

Further information on installation:
Used on an International 806 sailing yacht. Length: 8m. Rocna anchor used: 6kg. A larger 10mm teak plywood plate is screwed to the inside of the transom to distribute the greater load on the laminate of the transom structure. A layer of thickened epoxy was applied to both the inside of the load distribution plate and the outside of the transom anchor support to ensure the flat components can be screwed to the curved surface of the transom with a tight, friction-locking connection. Release wax was applied to the ship's side beforehand so that the two epoxy pedestals can be removed from the ship and are not permanently glued.

Did not use the advice .... The mount was too short for my anchor ..... will now solve it differently. \ R \ nand return the mount. \ R \ nBruss \ r \ nD. Menke

You need to push it down with something while hoisting an anchor. Also only bruce-type anchor (10kg) fits into this. I had to purchase also stainless anchor, swivel-joint, chain, chain box, roller-line. Would be nice to collect a complete packet (for others) for a sailing boat.