This is an average between different suppliers on 30 grade proof hot dip galvanized chain.

Chain Size	Proof Load Test	Breaking Load
3/8"	5,300 lbs	10,600 lbs
1/2"	9,000 lbs	18,000 lbs
5/8"	13,800 lbs	27,600 lbs
3/4"	21,200 lbs	42,400 lbs

Do not forget to match your shackles and the turnbuckle / swivel to the strength of your chain, not the size of the chain.

Many of these components are weaker than the chain strength.

“Breaking load” is the amount of weight that will break the chain, proof load test is the weight that was used to test / certify the strength of the chain when tested.

So when deciding on what chain you need, consult the manufacturer of your boat. The amount of force that your boat will exert on the chain during a hurricane will largely depend on your boats design. The wider the bow area at and below the waterline the more force and the larger the front profile of the boat above the waterline the more force it will exert on the chain based on the 150 mile per hour winds pushing against the boat. This will have a greater effect on the forces than the weight or length of the boat.

So once you know this you can select a chain size that will be adequate with a margin for safety. You will then also know how heavy a mooring you will need.

There are also several online calculators and forums that will help guide you.

This is your responsibility – it’s your boat, your investment. I will build any size mooring you want, install it and connect the chain you specify.