djmarchand is on the right track.After a block sized to suit the boat and conditions anticipated comes heavy ground chain, attached to a U-bolt or eye moulded into the block.The ground chain is only lifted by boat movement in stronger conditions, it in turn is shackled to lighter chain, which in turn attaches to the floating poly rope you eventually see at the surface,with a float buoy attached, plus line to attach to the mooring cleat. In our case that line branches into 2 forming a bridle to exert pull either side of the bow holding the boat better head to the wind, reducing side windage and loadings.Where lines coming onboard through hawse holes they are protected by plastic hose. Some people add a vertical rod on a float which can be easily grabbed by hand from the deck without a boathook.
Because constant boat movement causes considerable underwater movement, causing wear at the block eye,and shackles and generally,the whole system needs lifting,checking and servicing annually by a mooring contractor; that`s if you don`t want your pride and joy breaking free, colliding with other boats, until it goes ashore,with your insurance voided. BruceK