No some of us do have permanent moorings, just didnít see your post.
From the top of the mooring buoy swivel I have 10mm chain going up to the bow ĎDí ring which is also 10mm dia rod in a 50mm radius.
I use two hooks or karabiners on the ĎDí ring one in each direction, this should stop them coming undone by mistake
From the mooring buoy swivel I also run a 30mm dia rope that goes loosely over the tubes to the forward deck cleat, by keeping this loose it doesnít mark the tubes but if the ĎDí ring should fail this is back up
As too the sinker and sub sea bits and bobs, I have a large lorry (truck) tyre I filled with steel and concrete ( 500kgs) and dug into the mud at very low tide. Digging it in effectively doubles its weight but it is not a job for the fainthearted
Mouse any shackles with a cable tie because they do come undone, replace the rope every other year and check the chain annually, you will be amazed how quickly it rots
Donít use stainless underwater it's cr**
Divide everything by 25.4 to get imperial measurements or whatever you call your inches