Understanding

shackles

Generally shackles come in 2 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 Size0-14 ft 14-20 ft 20-30 ft 30-35 ft 35-40 ft 40-45 ft 45-50 ft 50-60 ft60-70 ft 70-90 ft 
 < 1,000 lbs< 5000 lbs< 11,000 lbs< 15,000 lbs< 20,000 lbs< 40,000 lbs< 50,000 lbs< 60,000 lbs< 70,000 lbs< 110,000 lbs
Shackle Specialty Alloy Grade (type 4 B)5/165/165/163/83/87/167/161/21/25/8
Chain Grade 30 BBB, Proofcoil1/41/45/165/163/83/87/167/161/25/8
Chain Grade 40 HT1/41/41/45/165/163/83/87/167/161/2

***Shackles are sized by their body dimension; the pin is usually one size bigger than the size of the shackle***