The Fortress FX-37 21LB Anchor is a trusted marine anchor for boats in the 46' to 51' range, delivering strong holding power without the bulk of traditional steel anchors. Trusted by boaters and experts worldwide, it combines advanced materials with practical design for performance, durability, and ease of use on every voyage.
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Precision-machined aluminum alloy: as strong as steel but about half the weight, making it easier to handle and store on deck.
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Disassemblable design: easy to disassemble for simple storage, transport, and use as a spare or storm anchor.
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Lifetime Parts Replacement Warranty: free replacement of any damaged anchor part, forever.
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Adjustable 32°–45° fluke angle: exclusive feature that dramatically increases holding power in soft mud bottoms.
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Tough anodized finish: corrosion resistant with a handsome and durable appearance.
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Sharper profile: sets faster and penetrates deeper into common sea bottoms for incredible holding power.
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Balanced 21 lb (9.5 kg) weight: optimized for 46'–51' boats, balancing performance and manageability.
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Bottom versatility: designed to hold across different bottoms, including hard sand and soft mud.
The FX-37 brings together strong performance with practical durability: a lighter, sharper, and more versatile anchor that’s easy to handle on deck, simple to store, and built to endure tough marine conditions. Its superior hold in a range of bottoms—from hard sand to soft mud—means you can anchor with confidence in diverse shores and seasons, while the lifetime warranty ensures continued reliability on every voyage.
| Feature | Benefit |
Precision-machined from an aluminum alloy that is as strong as steel, but only half the weight. | - Easy to manage weight
- Rustproof
- Sharper than heavy, dull-edged steel anchors
- Will set faster and penetrate deeper into common sea bottoms for incredible holding power
|
| Can be disassembled | - Excellent as a spare or storm anchor
- Easy to store
|
| Lifetime Parts Replacement Warranty | - Free replacement of any damaged anchor part...Forever!*
|
| Adjustable 32 to 45 fluke angle | - Exclusive and patented feature which dramatically increases holding power in problem soft mud bottoms
|
| Tough anodized finish | - Handsome and durable appearance
- Corrision resistant
|
| FORTRESS SELECTION GUIDE
|
| Model | FX-7
| FX-11
| FX-16
| FX-23
| FX-37
| FX-55
| FX-85
| FX-125
|
| Boat Length |
| ft
| 16'-27'
| 28'-32'
| 33'-38'
| 39'-45'
| 46'-51'
| 52'-58'
| 59'-68'
| 69'-150'
|
| m
| 5-8
| 8-10
| 10-12
| 12-14
| 14-15
| 16-18
| 18-21
| 21-46
|
| Weight | lb
| 4
| 7
| 10
| 15
| 21
| 32
| 47
| 69
|
| kg
| 1.8
| 3.2
| 4.5
| 6.8
| 9.5
| 14.4
| 21.2
| 31.1
|
| Replaces Steel Anchors | lb
| 6-9
| 10-13
| 14-18
| 19-28
| 33-50
| 50-65
| 70-90
| 100-170
|
| kg
| 3-4
| 5-6
| 6-8
| 9-13
| 15-23
| 23-29
| 32-41
| 45-77
|
| HOLDING POWER |
| Model
| FX-7
| FX-11
| FX-16
| FX-23
| FX-37
| FX-55
| FX-85
| FX-125
|
| Working Load
| | | | | | | | | |
| lb
| 700
| 900
| 1.250
| 2,000
| 3,000
| 4,000
| 5,250
| 6,750
|
| kg
| 318
| 408
| 567
| 907
| 1,351
| 1,814
| 2,381
| 3,062
|
| 32 Degree Hard Sand Holding Power
| lb
| 2,800
| 3,600
| 5,000
| 8,000
| 12,000
| 16,000
| 21,000
| 27,000
|
| kg
| 1,270
| 1,633
| 2,268
| 3,629
| 5,443
| 7,258
| 9,536
| 12,247
|
| 45 Degree Soft Mud Holding Power
| lb
| 840
| 1,080
| 1,500
| 2,400
| 3,600
| 4,800
| 6,300
| 8,100
|
| kg
| 381
| 490
| 680
| 1,089
| 1,633
| 2,177
| 2,858
| 3,674
|
| 32 Degree Soft Mud Holding Power
| lb
| 420
| 540
| 750
| 1,200
| 1,800
| 2,400
| 3,150
| 4,050
|
| kg
| 191
| 245
| 340
| 544
| 816
| 1,089
| 1,429
| 1,837
|
| DIMENSIONS |
| Model | FX-7
| FX-11
| FX-16
| FX-23
| FX-37
| FX-55
| FX-85
| FX-125
|
| "A" Shank Length |
| in
| 24"
| 27"
| 31"
| 36"
| 40"
| 46"
| 51"
| 56"
|
| mm | 610
| 685
| 787
| 914
| 1,016
| 1,168
| 1,295
| 1,422
|
| "B" Fluke Length | in | 14"
| 16"
| 18"
| 21"
| 24"
| 27"
| 30"
| 33"
|
| mm | 356
| 406
| 457
| 533
| 610
| 686
| 762
| 838
|
| "C" Stock Length | in | 19"
| 22"
| 25"
| 29"
| 32"
| 37"
| 41"
| 45"
|
| mm | 483
| 559
| 635
| 737
| 813
| 940
| 1,041
| 1,143
|
| SUPPORT HARDWARE
|
| Model | FX-7
| FX-11
| FX-16
| FX-23
| FX-37
| FX-55
| FX-85
| FX-125
|
| Proof Coil Chain
|
| in
| 3/16"
| 1/4"
| 5/16"
| 3/8"
| 3/8"
| 1/2"
| 1/2"
| 1/2"
|
| mm
| 5
| 6
| 8
| 9
| 9
| 13
| 13
| 13
|
| Nylon Rope** | in
| 3/8"
| 3/8"
| 1/2"
| 5/8"
| 3/4"
| 7/8"
| 1"
| 1 1/4"
|
| mm
| 9
| 9
| 13
| 16
| 19
| 22
| 25
| 32
|
| Shackle Size
| in
| 1/4"
| 1/4"
| 5/16"
| 3/8"
| 7/16"
| 1/2"
| 5/8"
| 5/8"
|
| mm
| 6
| 6
| 8
| 10
| 12
| 12
| 16
| 16
|
| NOTE: Hard sand holding power figures above represent loads actually achieved on production FORTRESS and Guardian anchors under controlled horizontal pull conditions without dragging or resulting in disabling structural deformation. ** Rope recommendations are based on 25% of breaking strength. Rope must be in good condition. |
