APRIL 2016 http://www.yachtingmonthly.com 27A QUESTION OF
SEAMANSHIPSEAMANSHIPBill’s answer from P24
There’s no obvious reason for the skipper’s
unwillingness to explain why he wants
to veer the warp in addition to the chain,
which is already well in excess of the
guidelines for depth of water to length of
chain ratio. However, the rule of thumb
ratios for chain are based on achieving a
good catenary in the chain and a horizontal
pull on the anchor. The catenary needs to
be there to cushion any shock loads, which
might otherwise cause the anchor to breakout. In very shallow water there simply
is not enough depth for a catenary to
form, hence very little reduction in shock
loads as the boat responds to the yaw and
snatches which are imposed by the gusts.
In shallow water, a better way to cushion
these loads Is to use a fl exible cable,
typically a stretchy nylon warp, which will
use its elasticity rather that its weight to
smooth out the load of sudden snatches.
That is the theory behind ‘Warp is better
than chain for shallow water anchorages’
and the proponents of that theory usually
advocate plenty of warp because the more
you use the more cushioning stretch you
have. I’m not totally convinced because
in really gusty winds boats with all chain
cables tend to veer around much less than
those anchored with long warps.‘A windy night – how much
cable should you veer?’
How safe are
your guardrails?
Berthon are safety experts. To watch
a video on this important aspect,
go to: http://www.Berthon.co.uk/safetyCheck them with these handy tips from
the UK’s leading yacht refi t expertsImagine a pitching foredeck at night
with nothing to prevent you sliding off
the deck. Guardrails and stanchions can
save your life, so it’s essential to make
sure they are in good condition.
Ian Nicholson’s industry reference,
The Boat Data Book, gives good advice:
for a yacht up to 12m LOA, use wires
of at least 4mm diameter in 316 grade
stainless steel, 1x19 construction and a
maximum stanchion spacing of 2.2m.
Industry standard stanchion height (for
boats up to 15m LOA) is 610mm, but
some serious cruisers have stanchions of
800 to 900 mm. In addition:1
Guardwires should not be PVC-coated.
The wires should be visible and need
end fi ttings and tensioning methods at
least as strong as the breaking load of
the wire. Adjustment arrangements can
include simple lashings, turnbuckles or
integrated, adjustable forks.2
Lashings must be replaced regularly.
UV degradation weakens them over
time. Turnbuckles and other adjusters
should be regularly checked. Guardwires
should be tight enough so they do not
sag between stanchions, but not so tight
to cause wear spots as they pass through
the stanchions.3
Terminals should be secured fore
and aft with clevis pins and split pins,
which should be fully opened and either
taped over or covered with a bead of
silicone sealant to prevent them catching
on sheets and sails. Split rings should
not be used as they open too easily.4
Wires should be regularly checked.
If damaged, they must be replaced.
Stanchions should be securely fastened
to the deck and if bent or damaged, they
should be repaired or replaced.Why is my chain rusting?
Q
After 15 years my anchor chain rusted
badly at the boat end, partly because
the chain locker did not fully drain.
I have now fi tted a false fl oor and replaced
the chain. Should I leave the anchor locker
open to allow rainwater to wash away residual
seawater or keep it closed? I rinse the chain
after each cruise. The boat is kept in Croatia.
Vernon SherriffA
Metallurgy expert Vyv Cox replies:
Fifteen years is a good life for modern
galvanised chain. Whatever it is that
you are doing is pretty optimum, particularly
now that you have overcome the problem of
water lying in the locker. Although zinc is a
relatively reactive metal, it provides excellent
protection for steel chain in the form of
galvanising, provided that stable oxide fi lms
have been formed upon exposure to the
atmosphere. Where water remains between
chain links, these stable fi lms are broken down
and zinc hydroxide (white rust) is formed. Zinc
is consumed by this reaction, which ultimately
leaves the steel chain exposed to corrosion.
The best way to store chain for longer
periods is off the boat, exposed to thei air
and where rain water may dry as quickly as
possible. When the boat is afl oat, keep the
chain as dry as possible after rinsing.Is she safe to dry out?
Q
Due to a minor stroke a number of
years ago, I stopped sailing and sold
the boat in which I had sailed 12,000
miles around Europe. I am now making a
slow comeback, starting with an IP 24 that
I renovated. Having read Alastair Buchan’s
book Sailing an Atlantic Circuit (Bloomsbury,
£18) I am thinking of buying a Dockrell 27 like
his. She has a fl ared ‘scheel’ keel, but is she
stable enough to dry out on this? Would she
tolerate someone aboard without falling over?
Jonathan PearmanA
Alastair Buchan replies: I wish
Jonathan a speedy recovery. Narrow
sidedecks mean climbing over the
guardrail, creeping forward and then climbing
back over the guardrail when the foredeck is
reached. Removing the guardrails and their
stanchions between the cockpit and the pulpit
provides more shuffl ing space and allows me
to step directly onto the foredeck. A rollbar
over the front of the cockpit and a grabrail
around the coachroof means I can easily brace
myself against any unexpected motion and is
handy for clambering on and off the boat.
I would never dry out Margo without legs.
It would be unwise to assume a level and
even bottom anywhere. A strong gust or an
awkward wave could make her fall over. If I
was careful I could climb aboard if dried out
without legs, but I would prefer to use a rope
ladder over the stern rather than over the side.
PHOTO: ALASTAIR BUCHANA Dockrell 27 is a
solid boat, but may
be unstable if dried
out without legsPHOTO: VYV COX
This chain was only three years old. It was
stored wet and developed extensive white
rust. It was subsequently re-galvanised, (see
YM February 2011).