(10 and 15 m) of^1 / 2 - inch (13.48 mm wire
dia.) BBB chain leader.
Checking Rode
Specifications Against
ABYC Standards
We can check the anchor rode specifica-
tions against ABYC standard H-40, Anchor-
ing, Mooring, and Strong Points.First we
determine the design load for a working an-
chor from ABYC H-40 Table 1 (Table 24-1).
This is based on LOA or beam, whichever
is larger. Hold Fastis a powerboat 32 feet
LOA with a 12-foot beam (9.7 m LOA and
3 .65 m beam). Referring to Table 24-1, we
find a working anchor design load of
900 pounds or 4.0 kN (kilonewtons), or
408 kg. (ABYC tables give forces in kilonew-
tons. Multiply kN by 101.97 to get kgf—
kilograms of force.)
Then referring to ABYC H40 Table AP-1
(Table 24-2), we see that for this design load,
the recommend rode is
-^1 / 4 - inch (6 mm) BBB or proof-coil chain
-^1 / 4 - inch (6 mm) shackles
-^9 / 16 - inch nylon warp
In general, you will find that ABYC recom-
mendations for working-anchor-rode chain
and shackles are about a size smaller than
from the formulas and recommendations in
this chapter. The larger chain size makes
sense, as you also want the anchor rode to
work in storm conditions. The^5 / 16 - inch
(8.73 mm wire dia.) BBB chain specced
meets ABYC storm-anchor design loads.
A difficulty occurs with ABYC’s rope
anchor warp size recommendation. Nine-
sixteenth-inch (14 mm) is nearly^5 / 8 inch
(16 mm)—that is huge! Indeed,^9 / 16 - inch
(14 mm) nylon can be hard to locate, so you
may be forced to go up to^5 / 8 inch (16 mm),
in any case. One of the reasons for using
nylon anchor warp is to take advantage of its
elasticity. If the warp is too large, that elas-
ticity will not come into play except at
extreme loads, which is not what we’re after.
ABYC’s nylon anchor warp recommenda-
tions are much larger than those in Chap-
man’sPiloting, Seamanship, and Small
Boat Handling, which gives the same^3 / 8 - inch
(9.5 mm) nylon warp size recommendation
for a working anchor, and^1 / 2 - inch (12.7 mm)
nylon warp for a storm anchor for a boat of
Hold Fast’s dimensions. Nigel Calder, in
Nigel Calder’s Cruising Handbook, also
explains why ABYC nylon warp sizes appear
to be impractically large.
My recommendation is to use the nylon
anchor warp size from Formula 24-3 (or the
next size up when using a rope-to-chain
splice) and not the ABYC-based size, but you
should be aware of ABYC’s recommenda-
tions under ABYC H-40 and give them due
consideration.Chapter 24: Sizing the Anchor and Rode and Selecting Anchor-Handling Gear
TABLE 24-1. ABYC H40 TABLE 1—DESIGN LOADS FOR SIZING DECK HARDWARE
BeamLOA Sail Power Permanent Mooring Storm Anchor Working Anchor
ft. mft. mft. mlb. kN lb. kN lb. kN
10 3.0 4 1.2 5 1.5 480 2.1 320 1.4 160 0.7
15 4.5 5 1.5 6 1.8 750 3.3 500 2.2 250 1.1
20 6.1 7 2.1 8 2.4 1,080 4.8 720 3.2 360 1.6
25 7.6 8 2.4 9 2.7 1,470 6.5 980 4.4 490 2.2
30 9.1 9 2.7 11 3.4 2,100 9.3 1,400 6.2 700 3.1
35 10.7 10 3.0 13 4.0 2,700 12.0 1,800 8.0 900 4.0
40 12.2 11 3.4 14 4.3 3,600 16.0 2,400 10.7 1,200 5.3
50 15.2 13 4.0 16 4.9 4,800 21.4 3,200 14.2 1,600 7.1
60 18.3 15 4.6 18 5.5 6,000 26.7 4,000 17.8 2,000 8.9NOTE: Use the greatest of LOA or beam (Courtesy American Boat & Yacht Council, http://www.abycinc.org))