Subject: [harryproa] Re: survival in heavy seas |
From: Mike Crawford |
Date: 1/20/2014, 2:26 PM |
To: harryproa@yahoogroups.com.au |
Reply-to: harryproa@yahoogroups.com.au |
Luc,
QUICK ANSWER
Beam-mounted Speer section bidirectional kick-up retractable
rudders, preferably using tillers with long extensions as shown in
the solitarry and woodenboat designs, either a round or flat bottom,
schooner rig, non-rotating round masts, with one of the following
sail designs: Wharram soft wingsail, swing-wing junk-rigged
wingsail, junk sail.
MEDIUM ANSWER
There is no medium answer. Any complete answer explains the
reasoning behind each choice, starting with a specific
risk-mitigation philosophy, and then applying it to the selection.
Otherwise it's just one guy saying "daggerboards are fine" and
another guy saying "tell that to my friend who had to have his
catamaran towed when the crash box failed".
---
LONG ANSWER - BACKGROUND
You've definitely opened up a can of worms there. Safety is
definitely a subjective issue, largely depending upon your view of
risk.
Most of the sailing community is happy to accept risks that are
built into most designs, even if those risks are no longer
necessary. Take heavier-than-water monohulls rigged with diamond
stays and shrouds, fin keels with spade rudders.
Dismasting is quite ugly in the best case scenario and
catastrophic in the worst case. Why accept 50+ different points of
failure, many of which either can't be inspected, or if they can,
could have stress fractures and crevice corrosion that won't be
seen?
Losing your keel, either due to the failure of keel bolts, or to
hitting a submerged object or grounding, probably means either
sinking, living in a life raft, or living sideways in a boat that
hasn't sunk for some reason, with no good way to make landfall under
your own power.
Losing that spade rudder due to a manufacturing defect in the
stock, stresses that weren't anticipated, or a submerged log, could
sink the boat or render it unsteerable.
And it's always a really bad day when you sink a very heavy boat
simply because of a leak.
Why accept any of those risks?
Because they don't happen often? Because they're "normal"? Those
might be responses, but they aren't logical answers.
For a long time it was normal not to wear a seat belt, and yet
I've always worn one. Not because I'm a good boy, or because I'm
scared, but because I can do simple math. Reducing the risk of
death by 80% is worth having a strap of cloth across my body. No
matter how tough you are, you're not tougher than steel, glass,
asphalt, and telephone poles.
To me, here's the general logic for safety: If a risk is
potentially catastrophic (lose a life, limb, entire boat, life
savings, whatever), and you can eliminate it through good design,
and that choice carries a low penalty in terms of cost,
performance, and/or aesthetics, you do it.
I don't care that less than x% of cruising boats with in-mast
furling ever get stuck in a storm with a jammed furler -- I will
simply not spend huge sums of money to buy a boat with in-mast
furling and then take my family to sea on it. Not when mast track
with lazy jacks looks better, provides better performance, is much
less likely to fail, and if it does fail, is much more likely to
allow me to get the sail down. A wharram soft wing sail, or a junk
rig, would be even safer.
So: if we can substantially reduce the risk through good design,
we go for it.
Part of that is eliminating a risk, such as making sure bearings
can't fail by getting rid of them entirely. Part of that is
maximizing your ability to recover from failures that do happen,
such as resetting the fuse in a kick-up rudder instead of trying to
figure out how to fix a spade rudder that has broken its crash box
and jammed diagonally while water comes in the boat.
---
LONG ANSWER -- HARRYPROA
The first big step is to go with a boat that won't sink, which
basically means either a well-designed multihull with plenty of
floatation or an Etap monohull.
The next is to go with a harryproa for the many reasons explained
on the web site and in magazine articles.
Highlights:
- As Rob points out, a boat that is easier and simpler to sail
results in a more well-rested crew making better decisions, skips
the emergency-inducing laziness and fear involved with tending to a
foresail in a massive storm, and also allows less experienced crew
to man the boat if the skipper is lost or incapacitated.
- Shunting is infinitely easier than either tacking or gybing in
huge winds, and just as important, far less likely to result in a
dismasting or capsize.
- Beginners can learn and perform a shunt, even if they are weak
and the weather is heavy.
- The entire boat depowers, on any point of sail, when you
release the mainsheet, allowing you to handle an emergency.
- The bidirectional boat lets you claw off a lee shore, with
obstacles, without blowing a tack or losing ground to a shunt.
- Fewer strings to pull mean less confusion, fewer chances of
bad choices that lead to a disaster.
- Fewer strings to pull mean fewer chances of equipment failures
that lead to disaster.
- The unstayed rig lacks dozens of points of failure.
- There's a large, safe working area, to leeward, on which to
handle problems with sails.
- The harryproa has onger waterline for the money/weight
invested.
- Etc.
---
LONG ANSWER - SPECIFICS
Beam mounted kick-up rudders.
The beam-mounted rudders can kick up in both directions. That
doesn't matter 99.9% of the time, but the other 0.1% it's a big
deal.
As the saying goes, the only sailors who claim they've never run
around are either liars or those who have never gone to sea. There
are forces at sea that break rudders, even well-designed ones.
Perhaps there's a flaw in the material, perhaps you hit a log,
whale, or container that you can't see because it's stormy and
dark.
With a kickup rudder, the best failure case is that you reset your
fuse and get on with your day. The worst case is that you can't use
the rudder any more, but at least it's out of the water and there's
no damage to the boat.
Sure, you can make spade rudders strong, but everything can fail.
In the event of that failure, the likely result is that you can't
steer properly because either all or part of your rudder is stuck at
an uncontrollable angle, and given the location of the rudder, you
may not b able to fix it at sea. A worse case is that there's
also now water flowing into the boat.
There's a slight performance penalty for having surface-piercing
foils, which may end up requiring a few inches more depth and a
touch more wetted surface area.
So if you want to set an ocean crossing record, have infinite
funding, can access rescue services at will, and don't mind the boat
blowing apart, this matters. It also matters if you do coastal
racing and you don't care about the cost or boat damage penalties of
running a spade rudder into something hard.
However, if you don't have an unlimited budget, and/or are
concerned about being able get the boat back to land, the
performance penalty is negligible.
Since the beams are the strongest part of the boat, that's the
best place to mount them -- there's just about zero danger of
breaking the structure or introducing a leak. Any force that
damages the boat at that point is so great that all bets are off for
risk-mitigation.
Retractable rudders.
Being able to adjust depth is great for getting into really
shallow water (particularly if you can help steer with a schooner
rig), and being able raise the foils entirely is great for beaching.
Granted, you can make a strong spade rudder, But strong enough to
survive bouncing on the beach when that one rogue breaker sweeps
in? Maybe. But that's several tons of boat that gets jammed down
and forward, perhaps on a single rudder, when the boat lands, and
yet still needs to have working bearings that allow for smooth
steering afterwards. And if the rudder is actually strong enough to
take that, it may be so strong that it won't fail before causing
hull damage.
Plus, why introduce another point of failure?
Also, with the rudders fully retraxted, you can't trip over the
rudder on a steep wave.
You could argue that an untended spade rudder should feather as
needed, but will it feather in time? What if it jams? Small risks,
perhaps, but regardless, it's even safer to have no foils in the
water.
Bidirectional Speer sections.
Since you don't have to rotate them 270 degrees to shunt, you get
the following advantages:
- Quicker shunt off a rapidly-approaching lee shore
(particularly if you're hemmed in by either islands or boat
traffic).
- No one, such as inexperienced crew filling in for an
incapacitated captain, can forget to rotate them during an important
shunt.
Tillers instead of wheels.
Feel free to say I'm full of BS on this one, particularly since I
vastly prefer tillers to wheels. I always feel like I'm driving a
bus when I'm at a wheel, not sailing a finely-tuned instrument
that's in harmony with the sea and wind. It's possible that I
rationalize this choice because it's my preference.
In any case, there's just about nothing to fail with a tiller an a
hard extension, and not much more to fail if you have a hard linkage
to a second tiller.
But with wheel steering, there are a number of points of failure
with the quadrants and drive cable. I've had a cable-based steering
system fail more than once on a power boat, and I know others who
have suffered similar fates.
The tiller, on the other hand, is about as simple and reliable as
it gets.
Round or flat bottom.
Either round or flat should be fine. Both will let you slide a
bit on waves, and neither has a keel to trip over.
Round might provide a touch less lateral resistance, but in the
end, it may not matter. Since at least one Wharram catamaran, with
its sharper V-shaped bottoms, has survived a hurricane/cyclone
beam--on to the wind, the argument between round and flat could be
moot.
However, I'd probably skip the V and go with something more
slippery anyway.
Schooner rig.
Massive sail area for light wind, lower center-of-effort for
bigger winds, lower center-of-effort when under bare poles.
A telescoping unarig would be even better in terms of windage
during a storm, and in catching light air up high in calms, but
there's the chance, however small, that it could jam in the up
position. Ruh-roh. That would not be good in a survival situation.
The ability to steer with the sails is another plus for a schooner
rig in the event that both beam-mounted kickup rudders have failed
(which in itself is hard to imagine), or if only one rudder is lost
and you want to balance the sailing/steering forces.
In fact, if you had a schooner-rigged harryproa you could
potentially sail up to a remote tropical beach, beach the boat,
perform repairs, and then sail it off the beach, all without the use
of any rudders.
Finally, with sealed masts, a schooner rig may have enough
flotation to stop a capsize, at least on flat water.
Round non-rotating masts.
A fixed round pole represents the best failsafe average windage in
a gusty situation where the wind direction changes. Plus, there are
no bearings to build, jam, or fail, so the mast is never at the
wrong angle. You also don't have to worry about damaging the
bearings when inserting and removing the mast, nor about maintaining
them to ensure there's no salt or grit that could introduce
additional friction.
A rotating wing mast do better than the round pole due to its much
lower windage when properly aligned, but there are too problems with
that: a) it may not feather in time to prevent capsize or
structural damage if one of those weird powerful gusts comes out of
left field, and b) if the bearings fail, or slow down due to salt
deposits, the system doesn't work as intended. That's the key to
the phase "failsafe average windage". If the wing mast fails
perpendicular to the wind, or doesn't feather in time, it's a lot
worse than the round pole.
There are also no worries about a fixed mast getting stuck when
actually sailing, preventing you from feathering the sail or moving
to the opposite shunt. That could make for a very ugly day.
Sails.
The reasons for either Wharram-type soft wing sail, the swing-wing
junk rig, or the traditional junk rig, are:
- All three can be used with round non-rotating masts.
- All three skip the use of sail track and bolt ropes, skipping
a point of failure/jamming.
- All three can be patched or rebuilt from just about any type
of soft cloth imaginable, even in a remote village.
Water ballast (not mentioned above).
I'm not sure I'd go with water ballast because of the sheer amount
of wind required to capsize a low-windage 48' x 32' proa under bare
poles. Long before the wind gets that high, it's time to put out
one or more long series drogues to keep the poles in line with the
wind, keep the windward bows in the water during gusts, and keep the
boat from surfing down waves. Once the drogues are out, the water
should be unnecessary.
The reason I'd be on the fence is risks in the system failing.
While it would be nice to add a a thousand pounds to the boat's
weight, what can go wrong with the ballast system? If one of those
tanks breaks free, it would be a bad day for anyone inside the
boat. If the system were to dump it's water, you wouldn't sink, but
you'd risk having all the water run downhill on a steep wave,
reducing the boat's stability instead of increasing it.
I suppose if you kept the water in a number of well-secured
independent tanks mounted under the floorboards...
Not being able to decide on this one by the merits alone, I'd
probably skip it in order to make the boat simpler.
---
CONCLUSION
The boat described above is not only about as safe as you could
make it, but would also still be very fast, reliable, and
inexpensive to build. All of those are good things.
The telescoping rotating rig with in-hull rudders would probably
beat this boat if raced on-on-one, but that's of little consequence
to me.
If I'm racing, there aren't many boats under half a million
dollars that will beat a 48' ultrasafe harryproa in elapsed time, so
no worries there. And if I care about corrected time, the
performance gained by a slightly faster proa would be meaningless.
Remember, I'll be the first to admit that most of this could seem
like overkill. Case in point: every ocean passage made to date has
been done without the full combination of features involved, and yet
the vast majority of people have no problems.
But if you can make a wicked-fast boat even safer through good
design choices, why not?
- Mike
A newly built Alpha 42 catamaran was abandoned a couple of days ago in heavy seas. It had broken both rudders and was leaking apparently. The truth or the details are not important for this thread. It serves here as a reminder for cruisers to take such conditions very seriously.What is the safest HP design in these conditions? I would venture this design would feature round bottom hulls and retractable rudders & boards. Would water balast be a factor in general? Clearance of the beam? What would be musts and what just nice to have?Thank you.Luc