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Old 07-08-2018, 15:48   #211
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Re: Multihull storm tactics?

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Have you ever finished snorkeling at the beach, removed your fins, and then casually pointed them into the direction of the incoming waves? They won't point that way for long before they are ripped to the opposite (stable) direction... in the direction of water flow.
That test indicates that the rudder angle is unstable in reverse flow without steering system involved. It does not indicate about the level of structural safety of rudder system in survival conditions, when steering system is present and operated by person steering, autopilot, friction system, or a locking device (for example with a rope tied in to steering wheel) and possibly some level of jamming due to rudder shaft more or less elastically bending.
Neither does it indicate the amount of torque involved in that test. Any non zero torque will make the fins flip around.
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Old 07-08-2018, 16:01   #212
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Re: Multihull storm tactics?

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There is nothing difficult about that at all. I don't know what gave you that idea. A rudder in reverse can be stronger than the rudder going forward at the same speed, provided there is no slamming against a stop, simply because there is no stop in every boat. The maximum coefficient of lift is higher for forward flow than in reverse, thus the forces experienced caused by the flow are also higher. It really is that simple as long as there is no impact load against a mechanical stop.
If the rudder system of your boat is so badly designed by having a hard stop causing such hard impacts, it of course changes everything. But it's not impossible to fix to be far less dangerous.
NOW we are getting somewhere.
Your concept of good boat design is quite foreign to me.
I showed you a pic of the the very common, relatively hard rudder stops on a Lagoon 400.
Please show me a multihull WITHOUT any such rudder stops, on which your mythical backwards rudder can happily slice through the water with less forces than it endures going forward. (and no sudden stops to cause a failure)
This might be VERY helpful, given the thread title.
Oh and gudgeons and pintles provide the very worst abrupt stops, so maybe you wanna stay on spades?
Thanks in advance!
(if your answer is "haha just kidding all along- I wasted your time" then I say simply "well-played")
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Old 07-08-2018, 20:04   #213
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Re: Multihull storm tactics?

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A rudder in reverse can be stronger than the rudder going forward at the same speed, provided there is no slamming against a stop, simply because there is no stop in every boat.
Okay, let me help.
Let me tell you WHY you are having trouble finding an example of your make-believe no-rudder-stop boat among those on the high seas.
IT IS TOO DANGEROUS!

Your incorrect beliefs are quite dangerous, and I hope that everyone here understands that you are dead wrong on this. Please stop with your lift and drag comedy as this is a matter of life and death. Someone reading this thread may need to make a critical decision one day, and if they choose reverse rudder at speed they may lose the battle.

Don't take the word of a design engineer like me. Do yourself a favor and learn a little from storm sailing experts such as... oh I dunno... maybe the experts Lin and Larry Pardey themselves...

Make Your Boat Unstoppable - Avoiding Steering Problems by Lin and Larry Pardey | YachtPals.com
in a storm situation, steering failure can be the first link in the chain of events that build up until the crew members feel their lives are in jeopardy.
By limiting the travel of the rudder, these lines protect the gudgeons and pintles against shear and shock loading. This loading happens when a boat is suddenly shoved astern by missing stays during a tack in heavy weather, or when the force of a wave crest carries the boat bodily astern if it is lying head-on to a sea anchor.
Rudder stops are just as important for boats with wheel steering and for those with spade rudder configurations where the rudder shaft comes through the hull. Here they absorb shocks that could otherwise damage the steering quadrant, or any of the components that make up the steering system. Also, should any component of the steering system break down, the rudder stops will keep the rudder from jamming hard over and stressing the rudderpost.


Okay, here is a little lighter reading from Sail Magazine
https://www.sailmagazine.com/diy/know-your-rudder
Confirm strong stops: Rudder movement beyond around 35 degrees either side of center is undesirable. The absence of strong stops that prevent the rudder from exceeding these angles exposes it to the risk of being slammed over by a following sea or when powering in reverse. This risks jamming the rudder as the broadside position of the blade subjects the stock to a violent bending force.


Or maybe just google a respected boat designer such as Will Keene who will tell you what the stop angle should be and how stops should be placed to STAY ALIVE.

(rant over)
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Old 07-08-2018, 21:47   #214
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Re: Multihull storm tactics?

If you quizzed 1000 multihull sailors about deploying a drogue off the bow in storm conditions, 999 would say hell no. It's possible, but not probable, that one person out of a thousand would think this could be done. It would be like putting 5 bullets in a six shooter and playing russian roulette but having to constantly pull the trigger. It won't take long to die.

It's always funny to me when someone posts something that is obviously wrong, then instead of saying "Om, that really isn't a good idea" continues to defend the post.
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Old 07-08-2018, 22:22   #215
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Re: Multihull storm tactics?

The best way to see what catamarans do in storms,
Is look on youtube at cats in huge seas,
Not one that I have come across is using drogues or parachutes,
They are just sailing across the waves, Very comfortably as well,

Catamarans in huge waves,
Catamarans in bad weather,
Catamarans in storms,
Plus you never go up or down waves, You go across them, It keeps the speed down,
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Old 07-08-2018, 22:28   #216
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Re: Multihull storm tactics?

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Originally Posted by Palarran View Post
If you quizzed 1000 multihull sailors about deploying a drogue off the bow in storm conditions, 999 would say hell no. It's possible, but not probable, that one person out of a thousand would think this could be done. It would be like putting 5 bullets in a six shooter and playing russian roulette but having to constantly pull the trigger. It won't take long to die.

It's always funny to me when someone posts something that is obviously wrong, then instead of saying "Om, that really isn't a good idea" continues to defend the post.
One mixes feelings and logic when saying something is obviously wrong. Also this kind of ideas are necessary to invention.

So let me add next step !

Unscrew and loosen rudder posts and reverse them to 'look' backwards' and then deploy drogue from bow.

What is wrong with that ?
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Old 08-08-2018, 05:55   #217
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Re: Multihull storm tactics?

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Originally Posted by arsenelupiga View Post
One mixes feelings and logic when saying something is obviously wrong. Also this kind of ideas are necessary to invention.

So let me add next step !

Unscrew and loosen rudder posts and reverse them to 'look' backwards' and then deploy drogue from bow.

What is wrong with that ?
What's right with it? I personally wouldn't want to risk my life trying to invent a new storm tactic during a storm but have at it if that's something you think should be done.

Going backwards at any speed over a knot or two in heavy seas and strong winds in a catamaran is not right, regardless of the rudders, but especially because of them. The best thread on this forum for storm techniques in a storm was started by Yeloya about 8 years ago.

IMO, running downwind at 180 - 150 degrees towing a drogue is the best method until you run out of sea room. Then turning into the seas and motoring bare poled with both motors engaged maintaining 3 knots is second.
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Old 08-08-2018, 06:00   #218
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Re: Multihull storm tactics?

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The best way to see what catamarans do in storms,
Is look on youtube at cats in huge seas,
Not one that I have come across is using drogues or parachutes,
They are just sailing across the waves, Very comfortably as well,

Catamarans in huge waves,
Catamarans in bad weather,
Catamarans in storms,
Plus you never go up or down waves, You go across them, It keeps the speed down,
This video is by far the best I've ever seen of a cat in serious seas and high winds.



They are trailing a drogue and still hauling ass - forward. Imagine them sitting in the water trying to cope with this in reverse.
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Old 08-08-2018, 07:23   #219
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Re: Multihull storm tactics?

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Originally Posted by Palarran View Post
This video is by far the best I've ever seen of a cat in serious seas and high winds.



They are trailing a drogue and still hauling ass - forward. Imagine them sitting in the water trying to cope with this in reverse.
I wouldnt even think about it,
I have plenty of ocean to run in, So I just sail about 30 degrees off the wave top line, Or less, Depending how steep the waves are,
Almost beam on to the wave line,
Maximum boat speed I got was about 12 knots,
If it works, Its how I sail across the waves
It wont let me upload a video.
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Old 08-08-2018, 07:31   #220
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Re: Multihull storm tactics?

Tasman Sea crossing, Day 7 from Bundaberg,
Its on youtube,
Im motoring as Im not a good sailor and the wind was in the wrong direction,
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Old 08-08-2018, 07:45   #221
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Re: Multihull storm tactics?

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The best thread on this forum for storm techniques in a storm was started by Yeloya about 8 years ago.

.
Any idea what the name of the thread is? I would really like to read it.
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Old 08-08-2018, 08:22   #222
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Re: Multihull storm tactics?

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Tasman Sea crossing, Day 7 from Bundaberg,
Its on youtube,
Im motoring as Im not a good sailor and the wind was in the wrong direction,
All you have to do is copy the address and paste it here:


But it's obvious from your example that you don't know what storm force conditions are. Almost any boat can survive gale force conditions doing almost nothing.


Saleen, try searching "yeloya catamaran storm passive". If you can't find it I'll look later today.
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Old 08-08-2018, 08:41   #223
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Re: Multihull storm tactics?

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All you have to do is copy the address and paste it here:


But it's obvious from your example that you don't know what storm force conditions are. Almost any boat can survive gale force conditions doing almost nothing.


Saleen, try searching "yeloya catamaran storm passive". If you can't find it I'll look later today.
That was a chop, A bit more than a millpond, I dont know where you got storm tactics from in that video,
It was to show how I sail along the sides of waves, Nothing more,
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Old 08-08-2018, 09:03   #224
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Re: Multihull storm tactics?

Well, I don't want to argue with you but I got it from your post #219 where you were commenting on what you would do in relation to the video I posted on a thread titled "Multihull Storm Tactic's". If the thread title was "motoring on a mill pond" then your video would fit much better.

Maybe a better example of actually sailing along the sides of waves would be this one:
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Old 08-08-2018, 09:34   #225
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Re: Multihull storm tactics?

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Saleen, try searching "yeloya catamaran storm passive". If you can't find it I'll look later today.
Got it! Thank you.

http://www.cruisersforum.com/forums/...ing-60057.html
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