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From: Mike Brasler (no email)
Date: Mon May 30 2005 - 16:30:52 EDT
Wow that really was an invitation to flame wars, so get out your
lite-sabres.
ANCHORING ACCORDING TO US
OK what I am about to say is beyond speculation, it is our experience and it
works for us.
Disagree if you must, debate is healthy.
We originally joined the list in 1998 when we had just started cruising.
The information we got fromthis forum had proved invaluable, and we made
several purchasing decisions based upon other people's experience. We still
have the Trojan batteries, and the Aero6gen wind generator, that were
recommended here. Now its payback time.
Let me answer your final question first. You
asked "Why do most live-aboard permanent cruisiers go with all-chain?" Well
the answer is simple, its because we need our sleep. I would love to have
less
weight in the forepeak, but we are only underway a small percentage of the
time, the rest of the time we are at anchor, and then we want chain, lots of
it, and heavy.
Like an old timer once told me "IF there was any better breakfast than
Oatmeal,
racehorses would be getting it"
So let me pose a rhetorical question.
If there was anything better that chain, why are the CG the Navy and all
merchant
ships required to carry chain? Ok large ships have automatic capstans, were
not big enough for that.
Forget about High test chain, its false security, yes its strong but you
actually need the weight. Take it to an extreme, would you anchor with
spectran? weighs nothing, stronger than steel? No way. get low test
calibrated chain,
and have it hot dip galvanised four times! it will be even heavier. We have
half inch chain, and its now even thicker.
The thing that absorbs the shock is the catenary, that is the increased
effort required to raise and straighten the curve. To me its ridiculous to
buy high test chain , and then buy sentinels to increase the catenary
action, if youre going to throw your money away, choose a charity please.
Snubbers, we do not use snubbers, and will not, after one nearly lost us our
boat. We were achored in a lagoon (Baitiquiri in Cuba) and there was a
catabatic pulsating wind. It gusted, stretched the snubber, and then abated
for moments, before gusting again, the recoil of the elasticity in the
nylon snubber made us go forward each time, and of course at the end of the
forward
motion like most boats we headed-off and the next gust got us beam on (9x
more windage) we plucked the anchor out of its holding and dragged.(65lb
CQR) We went
back and reanchored without the snubber and had no problem. Here is the
reason: A catenary is a progressive force whereas stretched nylon behaving
according to Hookes' law within its limits of elasticiy, will "pull" hard
more of the way back until it has returned to its unstrained form. The chain
stops pulling when it "lands" on the bottom. These pulsating winds are not
rare occurrances.
As for snatching the anchor off the bottom because the chain is not elastic
etc...We have NEVER straigtened out our chain, its practically impossible,
the forces required increase logarithmically. So from dead calm, our 66000
pound boat would lie to her chain, in 40 knots sustained, the angle of the
chain at the bow is about 35 degrees declination from horizontal. At 90
knots (yes I was on the forepeak checking it) the same angle is about 20
degrees, what I would call "Bar taut" but there was still catenary to be had
in the gusts of 115 knots plus. This is rare, but after experiencing this
awsome, limb numbing (trouser filling) fear, and our anchor still held, its
very reassuring. That was with 30 metres (97') out in 6m (20') of water. We
had 80m out when waiting for hurricanes.
Theres a good old saying about chain, "It don't do you any good in the
locker"
We never use less that 20m of chain. We normally like a to have a 5 or 6 to
one scope, but have to modify this according to social reasons, in crowded
anchorages.
Get a big windlass and a cheaper chain, we can and have lifted our 350 feet
of all chain 1/2" with a 65Lb CQR on the end.
On Windlasses, We prefer a vertical capstan to horizontal because with a
vertical capstan the wrap angle of chain around the wildcat or gypsy is 270
degrees. On a horizontal the wrap angle is about 100 degrees, we have often
seen runaway chains on horizontal ones. An added advantage is that the motor
is usually inside the boat and less prone to damage.
We caulk our chain into the hole where it goes below deck with polyurethane
foam when we are going to be at sea for more than a day. Keeps the water out
and breaks away easily when we re-anchor. I was going to call it a
hawse-pipe but for the life of me I cannot remember the correct term, a
hawse pipe goes from the capstan thru the deck and out the topsides, not
into the ship.
DO NOT GET A SWIVEL thanks to one of those smart shiny stainless steel
swivels, we are now the proud owners of a new (brand new) 30Kg Genuine Bruce
anchor. The guy who lost it broke his swivel. (EEEEK I hear you all say, but
theyre tested to x thousand pounds) Let me tell you how this swivel failed.
Most modern anchors have the hole where the chain attaches, made as a slot,
right, now this is to allow the "ear" of a shackle to pass through it. Now
try a little experiment, take your new shiny swivel and rotate it 90 degrees
to the "normal" pull, ok now slide it "backwards" to the far end of the
slot, ok now pull in the normal direction. If youre about to lose your
anchor you will find that the swivel got stuck, if you measure the distance
from the fulcrum to the pin, and from the fulcrum to the chain, you will
find a 3 or 4 to 1 ratio, in engineering this is known as "Mechanical
Advantage" or MA, if your chain is tested to 1000 pounds, and so is your
swivel, your jammed swivel could only be a 250 pound swivel, not to mention
that when they test them they put them in a tensile test machine, they apply
a pure linear force, when it is stuck like that, the pin is in shear, a
different story totally. OK so you have one, put a nut and bolt through the
back of the slot to prevent the swivel sliding there, it will help but its
not perfect.
More on swivels....we have never needed one, not in about 2520 days on the
anchor! If you are going to be in a tidal anchorage, like near an inlet of
the ICW, and face four turns a day, then use a swivel, but buy it in a
rigging shop, one that deals with cranes, not a stainless steel one.
Stainless steel. Another big subject, If you live on a dock, and only
occasionally anchor then stainless is OK, but if youre living on that chain,
and your life depends on it, get mild steel, DO NOT USE A STAINLESS SHACKLE,
stainless steel requires oxygen to remain stainless, it will die in the mud,
and guess what, it will look great until the microsecond before it FAILS.
Crevasse corrosion will allow the surface to remain bright and polished,
while the interior goes to shortbread.
DO use a bullpin and open your last link to allow passage of one size up
shackle pin. We have 1/2" chain and a 3/4" shackle. Using the bullpin (a
tapered
chisel that you hammer carefully in to make the last link rounder) to make
the shackle pin touch the chain link 180 degrees, not in a point load. No it
does not weaken the link unless you overdo it.
DO have ONE shackle if possible joining your chain to your anchor.
Do put lanolin or tallow on the threads of the shackle.
Do seize the shackle with wire, twice!
Never end for end your chain, rather cut 30 ft off, leave the cleanest chain
in the bottom of the locker! otherwise it will come out as one solid lump
one day.
Do dump an old anode in the bottom of your anchor locker.
Never shackle the bitter end of the chain to the inside of the boat! Use a
strong line that will support the entire weight of the chain, tie it to the
inside of the locker, and make sure that it is long enough to appear ON DECK
when you let everything out. This way you will be able to cut it away in an
emergency like a large ship dragging down on you, you cant go
forward, and recover your chain, coz he is there coming down on you, chuck
it! and come and get it tomorrow.
Anchor alarm, this is what we do, we have a diving weight on the end of a
long lanyard, 100 ft or so, once we are settled I toss the diving weight
overboard right below my cabin, I add another 20 ft of line, and then let
the wooden "X" frame that the line is wound around lie on the floor in my
cabin. If we drag or swing, clunk-clunk-clunk on the cabin floor wakes me
up. If youre a heavy sleeper, tie the thing around your toe.
If you have the time and inclination try to snorkel while the anchor of your
boat or another is being set. It is very informative to watch how they work
underwater, especially when backing down on it.
For the record we were going to buy a "Bugel" anchor in Turkey last year,
but after the tornado hit us in Sta. Ponca in the Balearics on 10 Sept 2003,
a neighbouring boat lying to a Bugel anchor dragged right past us in 90
knots of wind, and all chain. Our Bruce moved ONE FOOT going in deeper and
the blow came from the opposite direction that we set it.
We love our 30Kg Bruce and our 1/2" all chain, would not change it ever.
Lots more on anchoring, its always a hot subject, and for us its a way of
life.
Regards
Laura, Mike and Liz
http://www.seakin.com/gilana/default.htm
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