swing mooring chain length in 5 meters of H2O

[aquaslav]

I have a 37ft Catamaran on a swing mooring in sheltered water. Depth under keels close to zero @ low water and max 5 meters @ high. The present chain was set up about 10 years ago and needs to be replaced. What is the suggested length of chain? I have some galvanized 10x60mm chain and a meter of 20x80mm chain. I plan to run the 10mm chain up from the mooring block, then a 1 meter section of the heavy 20mm chain, and a further section of 10mm chain to the rope bridle. I am figuring the heavy meter of 20mm chain will act as a spring. Any thoughts? Any idea of total length?

[Captsteve53]

Here's the recommended normal way to install a permanent mooring,

1) Heavy chain = 2.5 x depth of water
2) Heavy chain joined to light chain via swivel shackle
3) Length of small chain = Maximum Depth of water
4) Buoy carries light chain
5) Length of pennant from buoy to chock = 2.5 x height of free board


Cheers Steve

[Captsteve53]

Below diagrams for the two different mooring ball to vessel attachments,

Cheers Steve

[aquaslav]

Thank you Steve! Looking for the definition of "Chock" in my Chapman's I found corroboration of your post Mooring a cat is somewhat different to mooring a monohull. The mooring buoy is attached to the rope bridle while the boat is away. Usually it also has a pennant with a small buoy on the end to facilitate recovery with the boat hook. On return the buoy is hauled out, the bridle is attached to the port and starboard ends of the forward beam, and the mooring buoy is hung on the seagull striker displaying the mooring number. Hope I'm not teaching you to suck eggs!

[aquaslav]

How long have you been @ Subic? I transited through Clark in the early 80's after abandoning a boat off Laog. We were headed for Subic! Japanese freighter picked us up and we came through Clark from Sumatra.redface.

[Captsteve53]

Yeah. was concentrating on the below water design,

Sailed here after 1 1/2 times Circumnavigation's in 1984, Had a boat building company in Mariveles Bataan (Entrance to Manila Bay) building GRP Yachts S&S and cruisers (Fjord and Shark Cat) until approx mid 1990's , all in all been here 33 years!!

Cheers Steve