Far more important than the
mooring size is the mooring attachments.
I was in
Hawaii when we were forced onto moorings by the state and I was on the Embarcadaro moorings in
San Diego. In both cases, the mooring blocks were 2-ton and I never heard of them being drug.
However, in both cases the State was responsible for maintaining the fastenings to the mooring blocks and in both cases there were several incidents of failure in either the chain or the fasteners.
In most cases, the failure was in the shackle that fastened the chain to the mooring block. In some cases it was the poor splicing of the thimble in the nylon
rode. The thimble would turn in the line and chafe through it. It was supposedly inspected by divers or actual lifting of the block (by barge and crane) every year.
When I first took my mooring in
San Diego, I dove on it myself. I found the shackle bolt completely unscrewed and ready to fall out. I went out and purchased my own shackle, installed it and wired it. I also replaced their
cheap, junk chain with 1/2" ships chain for the 1st 15', shackled to 20' of 3/8" BBB then I replaced the Nylon mooring line with 3/4" high quality line that I slpiced myself. I wouldn't trust them to do anything.