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08-03-2017, 04:31
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#46
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Registered User
Join Date: Nov 2007
Boat: TRT 1200
Posts: 7,268
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Re: Multihull in distress.
Wonder how long it would have taken them to make the 8 miles to shore in that RIB hanging of the stern.
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08-03-2017, 04:50
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#47
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Registered User
Join Date: Dec 2015
Posts: 3
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Re: Multihull in distress.
Any news on the vessel? Did she sink or has she been salvaged?
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08-03-2017, 05:07
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#48
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always in motion is the future
Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 18,862
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Re: Multihull in distress.
Quote:
Originally Posted by tp12
There's a few of us really. Plus the manufacturers that I spoke to and the rigger that I spoke to. But then Jedi's comment wasn't about whether they're engineered to fall over before capsizing; it was about the loads being incalculable.
Are you seriously suggesting you can't calculate loads on a multi for the purposes of rig design?!
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Exactly, ask any rigger: cat rigging is oversized until it stops failing too frequently. I'm really not joking or trying to slam cats... and it is not the static wind load which is easy to calculate; it is the dynamic loading on the rigging with both wind gusts and waves. The heeling of a monohull is a dampener that the cat doesn't have. Most advantages come with side effects and this is an example. Cats must renew their rigging in a much more strict regime than mono's because of this: not getting away with 20-30 years like some mono's can.
It isn't that bad: some production mono's that had their keels fall off or loose rigs overboard, were fixed in the same way (make stronger until it holds) but the engineers didn't have the excuse of not being able to calculate... they just made it too cheap.
__________________
“It’s a trap!” - Admiral Ackbar.
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08-03-2017, 05:20
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#49
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Registered User
Join Date: Apr 2013
Posts: 11,002
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Re: Multihull in distress.
Quote:
Originally Posted by s/v Jedi
Exactly, ask any rigger: cat rigging is oversized until it stops failing too frequently. I'm really not joking or trying to slam cats... and it is not the static wind load which is easy to calculate; it is the dynamic loading on the rigging with both wind gusts and waves. The heeling of a monohull is a dampener that the cat doesn't have. Most advantages come with side effects and this is an example. Cats must renew their rigging in a much more strict regime than mono's because of this: not getting away with 20-30 years like some mono's can.
It isn't that bad: some production mono's that had their keels fall off or loose rigs overboard, were fixed in the same way (make stronger until it holds) but the engineers didn't have the excuse of not being able to calculate... they just made it too cheap.
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A rigger is not the same as a structural engineer. Yes, you can design for shock loads.
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08-03-2017, 05:29
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#50
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Registered User
Join Date: Oct 2010
Location: Australia
Boat: TBA
Posts: 338
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Re: Multihull in distress.
Quote:
Originally Posted by smj
Wonder how long it would have taken them to make the 8 miles to shore in that RIB hanging of the stern.
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I agree that the rib could have been used, where had the wind gone??? even the seas were relatively calm, i suspect the damage came from a storm that had been and gone, this cat appeared to still be floating well wonder why they couldn't motor the thing to shore, seems a bit odd this whole rescue.
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08-03-2017, 06:29
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#51
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Moderator
Join Date: Jul 2009
Location: Sxm , Spain
Boat: CSY 44 Tall rig Sold!
Posts: 4,367
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Re: Multihull in distress.
Quote:
Originally Posted by LarsKessel
Any news on the vessel? Did she sink or has she been salvaged?
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Its docked in Aguilas Harbour, Spanish coast close to Almeria....The Privilege have as far i know 4 real watertight bulkheads, 2 in the bows and 2 aft....
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08-03-2017, 06:29
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#52
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always in motion is the future
Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 18,862
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Re: Multihull in distress.
Quote:
Originally Posted by valhalla360
A rigger is not the same as a structural engineer. Yes, you can design for shock loads.
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Really?! What kind of education does a rigger need before designing rigs for sailboats? Also, please point us to citations about designing for shock loads on a catamaran
Why post when you don't really know? Just whacking the Jedi huh
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08-03-2017, 06:44
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#53
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Moderator
Join Date: Jul 2009
Location: Sxm , Spain
Boat: CSY 44 Tall rig Sold!
Posts: 4,367
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Re: Multihull in distress.
Quote:
Originally Posted by valhalla360
A rigger is not the same as a structural engineer. Yes, you can design for shock loads.
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Not true..
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08-03-2017, 06:49
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#54
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Registered User
Join Date: Nov 2007
Boat: TRT 1200
Posts: 7,268
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Re: Multihull in distress.
Quote:
Originally Posted by neilpride
Not true..
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So all riggers are also structural engineers?
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08-03-2017, 06:52
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#55
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Registered User
Join Date: Apr 2013
Posts: 11,002
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Re: Multihull in distress.
Quote:
Originally Posted by s/v Jedi
Really?! What kind of education does a rigger need before designing rigs for sailboats? Also, please point us to citations about designing for shock loads on a catamaran
Why post when you don't really know? Just whacking the Jedi huh
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Riggers aren't the ones designing the rig. They are installing it. Most replace in kind or by rule of thumb.
Any structural engineer worth their salt can design for shock loads.
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08-03-2017, 06:59
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#56
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Moderator
Join Date: Jul 2009
Location: Sxm , Spain
Boat: CSY 44 Tall rig Sold!
Posts: 4,367
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Re: Multihull in distress.
Quote:
Originally Posted by smj
So all riggers are also structural engineers?
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At some point yes, look if you come to me with clean deck , without any OEM back support to redesign a new rig , nil, 0 ... no pictures or whatever info to help me to figúrate how looks like your previous rig, i have a tedious job in advance to redesign a new rig for you, from Wall thicknes to spreaders placement, angle from the chainplates to the tangs, lenght of the spar related to your draft, wire size, tangs and chainplates thicknes, pin sizes, etc,etc,,
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08-03-2017, 07:01
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#57
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Moderator
Join Date: Jul 2009
Location: Sxm , Spain
Boat: CSY 44 Tall rig Sold!
Posts: 4,367
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Re: Multihull in distress.
Quote:
Originally Posted by valhalla360
Riggers aren't the ones designing the rig. They are installing it. Most replace in kind or by rule of thumb.
Any structural engineer worth their salt can design for shock loads.
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Again, Riggers can redesign a new rig or replace a existing rig...
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08-03-2017, 07:39
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#58
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Registered User
Join Date: Dec 2014
Location: Summer Europe Winter Florida
Boat: Dufour Nautitech435/FP Venezia42/Baltec Visiona 40/Catalac 10m used as a river cruiser
Posts: 182
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Re: Multihull in distress.
I think it is a problem with the flyingbridge designed multihulls. In a sudden hard blow let go the mainsheet. But how to do that when in shelter one storey lower?
For me, as most of the time single hander the flybridge design was a no go. Not to forget the height of the boom above deck. You need to be valiant to climb to the boom to reef the main if something happend to the endless reefing lines.
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08-03-2017, 07:56
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#59
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Moderator
Join Date: Jul 2009
Location: Sxm , Spain
Boat: CSY 44 Tall rig Sold!
Posts: 4,367
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Re: Multihull in distress.
And oh well, i just found it that the Multi is a Privilege serie 7, as far i see they use a Carbon fiber mast without spreaders, not my cup of tea, i remember a old generation of Catanas with those CF sticks without spreaders, imposible to tune... Later the Spar maker quit doing bussines..
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08-03-2017, 09:23
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#60
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always in motion is the future
Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 18,862
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Re: Multihull in distress.
Quote:
Originally Posted by valhalla360
Riggers aren't the ones designing the rig. They are installing it. Most replace in kind or by rule of thumb.
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You're joking, right? A rigger may have apprentices that are at the bottom of the ladder and who do the grunt work but they can't call themselves rigger. A rigger can design a rig for any monohull, from chainplates, spars, spreaders to standing rigging. For cats they use rule of thumb like I explained before...
Quote:
Any structural engineer worth their salt can design for shock loads
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They tried for cats and failed every time. Again, when you make such bold statements but you can't come up with citations then it's nothing more than ignorance or at best opinion. I'm pretty sure I can come up with citations to support my position while you seem to sidestep and avoid it altogether which demonstrates that you can't back it up.
There's a rigger in this thread supporting my position so how long have you been in the naval architecture or rigging business to know it better?
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