Understanding Shackles

  • Generally Shackles Come two grades:

    • Industrial Grade (Type IV A)
    • Specialty Alloy Shackles (Type IV B)
  • Generally if you are trying to match the strength of your chain you can use these rules:

    • If sizing for BBB or Proof coil chain use Industrial Grade (Type IV A) shackle, one size bigger than your chain
    • If sizing for HT (G4) chain use Specialty Alloy Shackles (Type IV B), one size bigger than your chain
    • If sizing for stainless steel chain use a forged SS shackle that is one size bigger than your chain.
    • If sizing for duplex chain use a duplex shackle one size bigger than you chain
Boat Size Boat Size 0- 14 feet
< 1,000 lbs
14-20 feet
< 5000 lbs
20-30 feet
< 11,000 lbs
30-35 feet
< 15,000 lbs
35-40 feet
< 20,000 lbs
40-45 feet
< 40,000 lbs
45-50 feet
< 50,000 lbs
50-60 feet
< 60,000 lbs
60-70 feet
< 70,000 lbs
70-90 feet
< 110,000 lbs
Shackle
Specialty Alloy Grade
(type 4 B)
5/16 5/16 5/16 3/8 3/8 7/16 7/16 1/2 1/2 5/8
Chain Grade 30
BBB, Proofcoil
1/4 1/4 5/16 5/16 3/8 3/8 7/16 7/16 1/2 5/8
Chain Grade 40
HT
1/4 1/4 1/4 5/16 5/16 3/8 3/8 7/16 7/16 1/2
***Shackles are sized by their body dimension; the pin is usually one size bigger than the size of the shackle***
Understanding Shackles