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From: David Straton (no email)
Date: Tue May 09 2006 - 17:39:38 EDT
Hi list
I am very interested in the catamaran discussion, and should like to
change the subject line to something more relevant than
'Circumnavigating in a power-boat'.
Here's an article.
Cheers
Dave Straton
------------------------------------------------------------------------
Heavy weather sailing in multihulls
http://www.southwindssailing.com/articles/multihulls/HeavyAir.shtml
By Kevin Jeffrey and Charles E. Kanter
(Excerpted with permission from Sailor's Multihull Guide, authored by
Jeffrey and Kanter)
First, let us make the distinction between heavy weather sailing and
survival sailing. Heavy weather sailing is done in full control of your
circumstances and ability to manage your vessel. Survival is when you
pass that point and must take action to preserve life and property...a
subject for another time.
Historically, many situations that would have been survival situations
in other craft were just heavy weather sailing for catamarans. There is
a classic story by Robin Knox Johnson published in Cruising World. It is
his account of sailing his catamaran through Force 12 winds. There are
other similar experiences that support the notion that keeping the
vessel under way is perhaps the best survival tactic.
Little has been written specifically for survival situations in
multihulls. The basic reason for this lack of literature is the
astonishing safety record compiled by ordinary sailors in "off the
shelf" catamarans. For instance, at the time of the famous Fastnet
disaster, of which volumes have been written, there were two Prout
catamarans in the vicinity. They were shadowing the fleet as unofficial
entries. The racing fleet sailed into a serious storm. The carnage
caused by the storm was so great that a Committee On Safety From
Capsizing was formed. It consisted of the Society of Naval Architects
and Marine Engineers (SNAME), the United States Yacht Racing Union
(USYRU), and the United States Naval Academy (USNA), and others. The
purpose of this committee was to design a minimum stability formula for
ocean racing monohull yachts. The weather that was disaster to the
Fastnet fleet was considered merely "beastly weather for sailing" by the
two adjacent catamarans.
Heaving weather sailing--basic tactics
Knowing when to reef is the most important skill to develop for heavy
weather sailing. Then comes sail shape and sheeting angle. There are a
few generalities that will help you get started learning about heavy
weather sailing tactics:
* As the wind increases, move the sheeting point to leeward. This is
one of the best features of multihull sailing. Multihulls have a wide
sheeting base, which allows a greater angular choice for sail trim than
narrow boats. Ease off the traveller to move the main to leeward and use
an outside rail attachment point, stanchion base or toe track and car to
move the jib to leeward.
* Allow more twist in the sails as the wind strengthens and reduce
camber (flatten the sails). This is achieved in the main by slacking the
mainsheet and in the jib by moving the sheeting point aft.
* Reduce sail. You will find most multihulls just as happy with
reduced sail, and you will be surprised how little speed you really lose.
* Learn to use a barber-hauler to control your jib. A barber-hauler
does not need to be a fancy multipart tackle, but can be made from
almost anything, including just a length of line from the clew of your
jib to an appropriate turning point and to a winch.
* Slow down to a more moderate speed...like slowing down your car
when you come to a rough road.
* Choose sail combination according to direction. Downwind-reduce
main area first, then the jib. Upwind-reduce jib first, then the main.
This is just a rule-of-thumb. It must be tailored to the individual vessel.
* Expect to hand-steer downwind in big waves. Your autopilot will
not be able to react fast enough, nor can it anticipate waves. The trick
is never to allow yourself to be perpendicular to the wave, but always
to be at angle to it. That way you are always sailing downhill, and you
eliminate the chance of pooping or pitch-poling. Pooping is unheard of
in cruising catamarans, and pitch-poling comes from excessive speed
perpendicular to the waves.
Getting to windward
If you seriously feel the need to maximize your heavy-weather windward
ability under sail, then you must be prepared to change headsails for
the purpose. Roller reefing sails are good to a certain point. It must
be remembered that a sail is sewn to pull against the head, tack, and
clew with the luff supported by a stay. When a sail is partially rolled,
it is no longer pulling against the designed strong points but is
pulling against the luff and the foot where they roll around the stay.
While it is possible to do reasonably well with a partially rolled jib,
it is without doubt much better to have a sail specifically cut for that
purpose, such as a good storm jib.
On the other hand, if you do what most cruisers do and simply run your
engine about one third your normal cruising speed, you will go to
windward just fine.
This motor-sailing concept is almost the universal choice of cruisers
for going to windward in heavy weather. In a catamaran with twin
engines, it is usually only necessary to run one of the engines to gain
the desired effect.
How do I know when to reef?
This is the most often asked question concerning multihull safety. The
answer is deceptively simple: "It is time to reef when you first think
about it." This is not meant to in any way belittle the importance of
knowing that "time." As you get more experience with your particular
boat, the more feel you will get for the process. Let us compare
learning how to "feel" your boat, with how you learned to "feel" your
car. When you first learned to drive, how did you know when to start
slowing for a stop? If you started slowing too soon, you created a
traffic hazard. If you started too late, you wound up with a panic stop
or a rear end collision. How did you learn this subjective judgmental
skill? How did this judgmental process become habituated? The feel just
developed with experience.
Subjective and objective sailing
From the subjective point of view, when you begin to feel uneasy,
apprehensive, concerned, it is time to reef. When the boat no longer has
its feather light touch at the helm, it is time to reef. When the boat's
motion changes from its normal light, resilient feeling to one of
petulant obedience, it is time to reef. When the lee bow seems to want
to plunge and bury, it is time to reef. From the objective point of
view, when the apparent wind speed goes over 15 knots, it is time to
reef on most boats. When you are heeled two degrees more than normal, it
is time to reef. When you are no longer strong enough to crank in the
sails, it's time to reef. Reefing, as referred to in this section,
includes both headsail and mainsail. As a rule for masthead boats,
upwind reef the jib first, downwind reef the main first. It is hard to
generalize about fractional rigs. Sailing under main alone is typically
far more controllable. The fully-battened mainsail has the most sail
controls, is held on two sides by spars, and can be given optimum size
and shape.
Experience counts
There is no substitute for experience, and I suggest taking your
catamaran out in a controlled environment in strong winds, with some
capable crew. Sail it as hard as you can and try to lift a hull. You may
or may not be able to do it. You surely will learn a lot about how your
cat feels when you begin to reach the realistic usable limits. Never
sail your boat that hard again if you can help it!
Trimarans
A trimaran is far easier to judge when over-pressed than a catamaran as
the extreme initial stability of the cat muddies both sensory and visual
clues. A trimaran heels almost like a monohull, and you can visually see
the lee float being depressed. Since there is more heel, there is more
familiarity for those used to monohulls. As with any multihull, however,
the wide beam of a trimaran allows you trimming angles not available to
monohulls; thus you can have far more control and keep your power up
longer. A good multihull requires less power to move at speed because it
is lighter and does not have the hull speed limitation factor of a monohull.
From the editor: The Sailor's Multihull Guide, Avalon House Publishing,
1998, is a perfect starting point for anyone considering a multihull.
With hundreds of line drawing and specs on the current and older
multihulls, along with an encyclopedia of multihull information, it is
invaluable.
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Copyright © 1998, 1999 Southwinds Media. All rights reserved.
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