Anchor and Chain Sizing Guide
Use this table to match anchor mass, chain diameter and chain length. The figures are taken from the IACS equipment number tables — the same standard your classification society applies — so a chain and anchor selected from one row will be consistent with each other.
How To Use This Table
Find your chain diameter in the first column. That row gives the bower anchor mass your vessel should carry, the chain breaking load, and the chain length normally specified.
Don't know your chain size? Measure one link. Link length is approximately 6 × the chain diameter and link width approximately 3.6 × the diameter — so an 80mm long link is 80 ÷ 6 = 13.3mm chain, or 1/2". Send us measurements and photographs and we will identify it.
Chain Size, Anchor Mass and Chain Length
| Chain dia. | Imperial | Grade 3 breaking load | Stockless anchor | HHP anchor | Chain per anchor | Chain weight per shot |
|---|---|---|---|---|---|---|
| 20.5mm | 13/16" | 349 kN / 36 t | 660 kg | 495 kg | 5.5 shots (495 ft) | 265 kg |
| 22mm | 7/8" | 401 kN / 41 t | 780 kg | 585 kg | 6.0 shots (540 ft) | 300 kg |
| 24mm | 15/16" | 475 kN / 48 t | 900–1,020 kg | 675–765 kg | 6.5 shots (585 ft) | 360 kg |
| 26mm | 1" | 556 kN / 57 t | 1,140 kg | 855 kg | 7.0 shots (630 ft) | 420 kg |
| 28mm | 1-1/8" | 642 kN / 65 t | 1,290 kg | 970 kg | 7.0 shots (630 ft) | 490 kg |
| 30mm | 1-3/16" | 734 kN / 75 t | 1,440–1,590 kg | 1,080–1,193 kg | 7.5 shots (675 ft) | 565 kg |
| 32mm | 1-1/4" | 832 kN / 85 t | 1,740 kg | 1,305 kg | 8.0 shots (720 ft) | 635 kg |
| 34mm | 1-3/8" | 936 kN / 95 t | 1,920 kg | 1,440 kg | 8.0 shots (720 ft) | 720 kg |
| 36mm | 1-7/16" | 1,045 kN / 107 t | 2,100–2,280 kg | 1,575–1,710 kg | 8.5 shots (765 ft) | 800 kg |
| 38mm | 1-1/2" | 1,160 kN / 118 t | 2,460 kg | 1,845 kg | 8.5 shots (765 ft) | 895 kg |
| 40mm | 1-9/16" | 1,280 kN / 131 t | 2,640 kg | 1,980 kg | 8.5 shots (765 ft) | 1,000 kg |
| 42mm | 1-5/8" | 1,406 kN / 143 t | 2,850 kg | 2,140 kg | 9.0 shots (810 ft) | 1,100 kg |
| 44mm | 1-3/4" | 1,537 kN / 157 t | 3,060 kg | 2,295 kg | 9.0 shots (810 ft) | 1,200 kg |
| 46mm | 1-13/16" | 1,673 kN / 171 t | 3,300 kg | 2,475 kg | 9.0 shots (810 ft) | 1,300 kg |
| 48mm | 1-7/8" | 1,815 kN / 185 t | 3,780 kg | 2,835 kg | 9.5 shots (855 ft) | 1,440 kg |
Notes On The Figures
- A shot is a standard length of anchor chain: 27.5 m (90 ft). Chain is supplied in shots and joined with Kenter shackles.
- Chain per anchor is half the total chain length specified, since a vessel carries two bower anchors.
- Stockless vs HHP. A high holding power anchor achieves the same holding at roughly 75% of the mass of a stockless anchor, so it is lighter to handle and cheaper to ship.
- Breaking loads are Grade 3, the working standard for anchor and mooring chain. Joining shackles must always match the grade of the chain.
- Chain under 20.5mm is not normally supplied in Grade 3 — smaller sizes run Grade 1 or Grade 2.
What You Need For A Chain Replacement
A complete chain outfit for one anchor needs more than the chain itself:
- Chain — the number of shots from the table above
- Kenter joining shackles — one per shot
- Lead plugs — one per Kenter, mandatory, single use
- Drive pin punch — sized to the chain, for future disassembly
- End shackle — chain to anchor
We supply all of these, and Kenter shackles are held in stock in Montreal for immediate despatch.
Matching Anchors
We supply stockless and high holding power bower anchors to the masses shown above, certified to ABS or Lloyd's Register. Anchors are quoted to order — tell us your chain size or equipment number and we will quote the matching anchor.
Need Help Sizing?
Send us your chain measurements, your vessel's equipment number, or photographs of the existing chain and anchor, and we will tell you what you need. We answer technical questions whether or not you order from us.
Figures derived from IACS equipment number tables and IACS UR A1. Supplied for guidance — confirm requirements with your classification society or surveyor.
Dibblee Industries Ltd. / Les Industries Dibblee Ltée, Montreal, Quebec.