Mantus Marine


Mantus Anchor Swivel


The strongest link – the Mantus anchor swivel is stronger than its corresponding grade 40 chain. (WLL is 1/5 UBS)

Integrated swivel shackle design completely eliminates side loading, making this the safest anchor swivel on the market.

The pin on the chain side of the swivel is the strength-limiting part since the geometry of the chain determines the pin size.

The Mantus anchor swivel and shackle is the first to feature an oblong pin to maximize the pin strength. With the aid of computer modeling and physical testing, we truly created a swivel that is the strongest link.

Note the innovative shackle bolt design – no shackle dog! This slim hex head design (with holes for safety wire) offers a slimmer profile making it easier for translating through your bow roller.

  • 316L stainless steel, precision cast and electro-polished body
  • Pin made from duplex stainless steel and is mechanically polished and electro-polished.
swivel with wire and anchor

Swivel Sizing Guide

Imperial Chain1/4 – 5/165/16 -3/83/8 -1/2
Metric Chain6mm – 8mm8mm – 10 mm11 mm – 13 mm
UBS (Ulitmate Breaking Strength)15,000 lb/ 6.8 T21,700 lb/ 9.8 T35,000 lb/ 16 T
WLL (Working load limit) (Safety Factor 5)3000 lb/ 1.5 T4,340 lb / 2 T7,000 lb / 3.2 T

These numbers are used to generate the recommendations for the Swivel Sizing

Swivel Specifications 

Grade 30 ChainS1S1S2S2S3

Chain Size (in)1/4 (6 – 7mm)5/16 (8mm)3/8 (10mm)7/16 (11mm)1/2 (13mm)
Recommended swivel model for a given chain type and size     
Grade 40 Chain(G4 HT)S1S1S2S3S3
Grade 70 ChainS1S2S3S3NA

Recommended swivel model for a given chain type and size

Understanding Your Chain


Imperial Chain TypeG30 (Proofcoil/BBB) (lb) UBS / WLL / WLL inflated*G40 HT (lb) UBS / WLL / WLL inflated*G70 HT (lb) UBS / WLL / WLL inflated*
1/45,000 / 1,2507750 / 1,938 / 2,6009,450 / 2,350 / 3,150
5/167,600 / 1,90011,600 / 2,900 /3,90014100 / 3,500 / 4,700
3/810,600 / 2,65016,200 / 4,100 / 5,40019800 / 4,950 / 6,600
7/16NA21,600 / 5,400 / 7,20026,250 / 6,560 / 8,750
1/218, 000/ 4,50027,600 / 6,900 / 9,20033,900 / 8,475 / 11,300

UBS -Ultimate Breaking Strength (lb) WLL – Working Load Limit (lb) WLL Inflated* – Working Load Limit inflated using a a different safety factor than is standard. See note below.
*Grade 40/70 chain types claim inflated working load limit values. Typically, chains working load limit is calculated as 1/4th of the ultimate breaking strength.

Published WLL for Grade 70 /Grade 40 chain are calculated using the safety factor of 3, or UBS/3 = WLL. (G4 HT) is only 50% stronger than G30 chain and Grade 70 chain is only 20% stronger than G40 chain and 85% stronger than G30 chain. Thus, WLL values we use to size you with the correct swivel are WLL = UBS/4 regardless of the chain type.

For Mantus Swivels, we use a safety factor of 5 when determining the WLL recommendations.


Swivel Dimensions

Scroll down for all swivel dimensions

Assembly Instructions