Page 2 - Section 1 Anchors

Recommended Applications 1
Stockless
Snug- Stowing®
Lightweight
LWT® Danforth
Stato®
Moorfast®
Boss
Offshore Rig Mooring
X
X
X
X
X
Supply/Support Vessels
X
X
Pipelay Barges
X
X
Fixed Mooring
X
X
X
X
X
Commercial Ships
X
X
Tugboats
X
X
X
Supertankers
X
Minimum Performance Characteristics
Holding Power Ratio2
3:1
5:1
9:1
9:1
9:1
9:1
32:1
Depth of Penetration (ft)
9-10
17-20
17-20
17-20
17-20
17-20
35-40
Breakout Force Ratio
2:1
3:1
5:1
5:1
5:1
5:1
6:1
Fluke-to-Shank Angle (degrees)
45°
43°
30°
30°
23°
34°
34°
Holding Power Ratio2
7:1
14:1
20:1
20:1
20:1
20:1
25:1
Depth of Penetration (ft)
3
6-8
6-8
6-8
6-8
6-8
10-15
Breakout Force Ratio
2:5:1
6:1
8:1
8:1
8:1
8:1
12:1
Fluke-to-Shank Angle (degrees)
45°
43°
30°
30°
34°
34°
34°
Optional Swivel Shackle3
X
X
X
X
Padeye for Pendant Buoy Line
X
X
X
X
X
ANCHORS
Because the anchor is the key to effective mooring or anchoring it is essential to know what to expect from various types. Any anchor’s performance is dependent rst upon its ability to bite into the bottom through the ploughing effect of its ukes and secondly upon its ability to maintain a continuous resistance to drag once it is implanted in the bottom.
Therefore, the optimum design of an anchor is in uenced primarily by the speci c composition of the ocean oor, which is generally categorized into three groups: mud, sand, and rock or marl. Mud varies the most in consistency and offers little resistance to dragging forces. Sand is almost ideally consistent and anchors speci cally designed for sand bottoms reach excellent holding ef ciency. On the other hand rock or marl is very poor holding ground, where an anchor’s dead weight is its only asset.
An anchor’s ef ciency is expressed in holding-power ratio, that is the holding force per anchor weight. The proof test involves applying a static load to the assembled anchor to
test its structural design and material properties as related to the holding force.
The holding power of an anchor is affected greatly by the angle of its ukes. In order for the ukes to enter the bottom of an angle that will allow the crown or head to penetrate to a depth producing maximum ef ciency, the angle of the uke to the shaft should approximate 50 degrees in the mud bottoms and 30 degrees in sand.
Fluke-to-Shank-Angle
Anchor holding-power is also dependent upon other bottom conditions, the duration of drag and the ratio between the length of the mooring line and the water depth.
SELECTION
1 These recommendations are based upon usage practice. Deviations are acceptable.
2 These are minimum values only; actual bottom conditions could increase holding power considerably. 3 Swivel shackles can be used to replace anchor shackle, anchor connecting link, and swivel.
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COAST AND EAST COAST TO EXPEDITE DELIVERIES. GIVE US A CALL AT (800) 233-8014. WWW.ANCHORMARINEHOUSTON.COM
14
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SAND MUD
ANCHORS