Cruisers Forum
 


Join CruisersForum Today

Closed Thread
 
Thread Tools Rate Thread Display Modes
Old 11-12-2014, 12:26   #856
Registered User
 
neilpride's Avatar

Join Date: Jul 2009
Location: in the world
Boat: csy 44 tall rig.
Posts: 3,099
Re: The Yard Guys

Thats quite simple Smack, maybe that Passport got a keel stub and proper glassed masive beams and stringers to spread loads, those flat hulls holding thousands of iron pounds without a real good structure are not grounding friendly,, is not the first Jeaneau with a hull cracked after a grounding....
__________________

__________________
neilpride is offline  
Old 11-12-2014, 12:29   #857
Registered User
 
Exile's Avatar

Join Date: Sep 2010
Location: Land of Disenchantment
Boat: Bristol 47.7
Posts: 2,961
Re: The Yard Guys

Why do you assume that groundings & hitting stuff aren't a reasonably foreseeable part of bluewater cruising, even for accomplished & experienced sailors? Collision bulkheads and watertight compartments are not limited to aluminum, high latitude "expedition" boats. Boats like Amel's & Calibers have them too. Maybe it's overkill for most, but you can argue that airbags in your car are too. Maybe it's an image thing -- you know, not "cool" to contemplate the downside of going "fast."

Quote:
Originally Posted by smackdaddy View Post
This boat "survived it" too apparently. As I pointed out above, we're really talking about the extent of the damage.

Yes, we are, and the repair costs that go along with that. You mean that the fact that the Jeanneau didn't just sink makes the build "good enough" for bluewater cruising? Maybe I'm not understanding the point you're trying to make.

But two questions here:

1. In terms of the type of force that will be applied in a grounding, how is your Passport 47 different than these boats...or even this Oyster 72...




Passport 47:



2. Are you absolutely certain there was literally NO damage or "fatigue" to the glass in the hull, the keel/keel-structure, the stiffeners, the tabbing, etc.? If so, how?

A good, thorough survey I suppose. So are you saying that you're better off with more damage because it can be more readily seen??
__________________

__________________
Exile is offline  
Old 11-12-2014, 12:46   #858
Registered User
 
Polux's Avatar

Join Date: Nov 2011
Location: Portugal/Med
Boat: Comet 41s
Posts: 5,765
Re: The Yard Guys

Quote:
Originally Posted by smj View Post
Wouldn't the heavier stronger boat have more inertia when hitting the rock than the lighter boat? May cause similar damage.


Sent from my iPad using Tapatalk
yes, the heavier the boat, the bigger the energy on the impact. If it was a rock, it would certainly have damaged the lead, as it damaged on the Dockhead's Moody. The results of an hard growding on the boat structure are not necessarily visible and those are the worse ones. I remember some years back a beautiful, very expensive and well built Sweden yacht that lost the keel on an Atlantic crossing. It was know after that the boat had suffered a very hard growding but as the damage was superficial and apparently there was no structural damage they repaired only what they could see. Big mistake.

Today there are sophisticated tools. I have a friend, a sophisticated yard guy that is on the process of patenting a new more evolved system based on medical devices. He use it on my boat when I suffered a lateral blow from a 55T motorboat going fast astern, to see if there was internal delamination on both sides of the core and the images were pretty amazing, you could saw like if you were looking at a photo of a cut on the hull. That one does not understand why someone wants to cross an Ocean on an old Amel
Polux is offline  
Old 11-12-2014, 14:56   #859
smj
Registered User

Join Date: Nov 2007
Boat: Searunner 38 catamaran
Posts: 3,654
Re: The Yard Guys

Quote:
Originally Posted by Polux View Post
yes, the heavier the boat, the bigger the energy on the impact. If it was a rock, it would certainly have damaged the lead, as it damaged on the Dockhead's Moody. The results of an hard growding on the boat structure are not necessarily visible and those are the worse ones. I remember some years back a beautiful, very expensive and well built Sweden yacht that lost the keel on an Atlantic crossing. It was know after that the boat had suffered a very hard growding but as the damage was superficial and apparently there was no structural damage they repaired only what they could see. Big mistake.



Today there are sophisticated tools. I have a friend, a sophisticated yard guy that is on the process of patenting a new more evolved system based on medical devices. He use it on my boat when I suffered a lateral blow from a 55T motorboat going fast astern, to see if there was internal delamination on both sides of the core and the images were pretty amazing, you could saw like if you were looking at a photo of a cut on the hull. That one does not understand why someone wants to cross an Ocean on an old Amel

Would that be thermal imaging?


Sent from my iPad using Tapatalk
__________________
smj is online now  
Old 11-12-2014, 15:48   #860
Registered User
 
Polux's Avatar

Join Date: Nov 2011
Location: Portugal/Med
Boat: Comet 41s
Posts: 5,765
Re: The Yard Guys

Quote:
Originally Posted by smj View Post
Would that be thermal imaging?
I believe it has more to do with ecography.
Polux is offline  
Old 11-12-2014, 15:51   #861
Registered User

Join Date: Jan 2006
Location: North Carolina
Boat: 44 footer
Posts: 923
Re: The Yard Guys

Alright yard guys, show of hands how many externally ballasted fiberglass boats you've seen with a loose keel...

Edit: Traditional full keel or cutatway forefoot...

I've only seen one, and that was courtesy of a hurricane and a rock jetty... Not a grounding.

Zach
__________________
Zach is offline  
Old 11-12-2014, 16:00   #862
Registered User
 
neilpride's Avatar

Join Date: Jul 2009
Location: in the world
Boat: csy 44 tall rig.
Posts: 3,099
Re: The Yard Guys

Quote:
Originally Posted by Zach View Post
Alright yard guys, show of hands how many externally ballasted fiberglass boats you've seen with a loose keel...

I've only seen one, and that was courtesy of a hurricane and a rock jetty... Not a grounding.

Zach

I never see one....
__________________
neilpride is offline  
Old 11-12-2014, 16:08   #863
Registered User
 
neilpride's Avatar

Join Date: Jul 2009
Location: in the world
Boat: csy 44 tall rig.
Posts: 3,099
Re: The Yard Guys

This is very very interesting...

http://www.boatdesign.net/forums/att...tion-study.pdf
__________________
neilpride is offline  
Old 11-12-2014, 16:24   #864
Registered User
 
avb3's Avatar

Cruisers Forum Supporter

Join Date: Jul 2010
Location: Florida/Alberta
Boat: Lippincott 30
Posts: 9,913
Images: 1
Re: The Yard Guys

Quote:
Originally Posted by neilpride View Post
I scrolled through it, but to be honest, I could not draw an conclusion out of it that would be useful to me.

What did you see in it that was important?
__________________
If your attitude resembles the south end of a bull heading north, it's time to turn around.
avb3 is offline  
Old 11-12-2014, 16:31   #865
cruiser

Join Date: Jun 2008
Posts: 1,132
Re: The Yard Guys

Quote:
Originally Posted by Exile View Post
Why do you assume that groundings & hitting stuff aren't a reasonably foreseeable part of bluewater cruising, even for accomplished & experienced sailors? Collision bulkheads and watertight compartments are not limited to aluminum, high latitude "expedition" boats. Boats like Amel's & Calibers have them too. Maybe it's overkill for most, but you can argue that airbags in your car are too. Maybe it's an image thing -- you know, not "cool" to contemplate the downside of going "fast."
I fully assume groundings and even hitting stuff is a foreseeable part of bluewater cruising. After all, aren't several production boats doing things like kevlar reinforcement in hulls (e.g. - Hunter)?

I'm just saying being "surprised" at damage from striking a rock at hull speed - or, worse, assuming there "should be none in a 'real boat'" - is a little strange. And trying to say that this represents poor construction in any way is a serious stretch.
__________________
smackdaddy is offline  
Old 11-12-2014, 16:36   #866
Registered User
 
neilpride's Avatar

Join Date: Jul 2009
Location: in the world
Boat: csy 44 tall rig.
Posts: 3,099
Re: The Yard Guys

Quote:
Originally Posted by avb3 View Post
I scrolled through it, but to be honest, I could not draw an conclusion out of it that would be useful to me.

What did you see in it that was important?

Page 9, cant copy paste from the report.
__________________
neilpride is offline  
Old 11-12-2014, 16:36   #867
cruiser

Join Date: Jun 2008
Posts: 1,132
Re: The Yard Guys

Quote:
Originally Posted by Zach View Post
Alright yard guys, show of hands how many externally ballasted fiberglass boats you've seen with a loose keel...

Edit: Traditional full keel or cutatway forefoot...

I've only seen one, and that was courtesy of a hurricane and a rock jetty... Not a grounding.

Zach
How many builders are still doing those these days?
__________________
smackdaddy is offline  
Old 11-12-2014, 16:39   #868
Senior Cruiser
 
Cheechako's Avatar

Cruisers Forum Supporter

Join Date: Aug 2006
Location: Skagit City, WA
Posts: 19,363
Re: The Yard Guys

Quote:
Originally Posted by smackdaddy View Post
I fully assume groundings and even hitting stuff is a foreseeable part of bluewater cruising. After all, aren't several production boats doing things like kevlar reinforcement in hulls (e.g. - Hunter)?

I'm just saying being "surprised" at damage from striking a rock at hull speed - or, worse, assuming there "should be none in a 'real boat'" - is a little strange. And trying to say that this represents poor construction in any way is a serious stretch.
That's really the heart of it isn't it? two camps......
The one I'm in fully expects to be able to hit a rock with the hull or keel and have little if any damage and also believes a boat that typically wont DOES represent poor construction.
After all... even today's cars are suppose to survive 5 mph without damage as I remember..... water absorbs a lot of energy
__________________
"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard











Cheechako is offline  
Old 11-12-2014, 16:58   #869
Registered User
 
avb3's Avatar

Cruisers Forum Supporter

Join Date: Jul 2010
Location: Florida/Alberta
Boat: Lippincott 30
Posts: 9,913
Images: 1
Re: The Yard Guys

Quote:
Originally Posted by neilpride View Post
Page 9, cant copy paste from the report.
You mean this:

It is not possible to relate the speed directly to grounding force and in any case this would be meaningless as a low speed impact on rock may be more damaging than a high speed impact on mud. The mechanics of impact of yachts with containers, berg-bits or whales defies simple analysis. Solid mechanics would need to be factored in - quite inappropriate for a simple standard. This is a crude deterministic approach to a probabilistic load case and should be treated with caution.

Notwithstanding this, to give a feel only for the effective decelerating force (applied at the centre of gravity) implied by 0,8g (10m boat) or 1.1g (20m boat), assuming a constant impulse approach, a boat travelling at the hull speed would stop in about 0.5 second (translation only).

The load applied at the keel would cause a bow down attitude of (very roughly) 0.5m at the bow. This all seems to constitute a pretty severe load case. Please note again – very rough figures.

It emerged from the validation that some boats, particularly those with no girders had little hope of complying with this load case, without substantial local reinforcement.

It is important to recognise differences between the risk/consequences of impact loads on ocean racing boats with those of typical recreational craft. Hence, it was felt sensible to have a dual grounding load case approach; NORMAL and ENHANCED. Designers/builders could opt for either.

A category A or B yacht need not necessarily be designed to impact Type II. It is for the designer or builder to decide. Type II may be applicable to ocean-going racing yachts in collision with floating objects, ice flows or marine creatures. For other category A or B craft (while designed to the appropriate requirements in all other respects) such a load case may not be appropriate. Whatever type is selected, the following note shall be included in the owner’s manual to the effect: ‘This boat has been designed to a Impact Type [I] [II] (delete as necessary) grounding scenario as defined in ISO-12215-9, where the craft is expected to be operating at [low] [high] speed prior to the impact (delete as necessary). While compliance does not guarantee that the boat will suffer no damage in such a grounding, the resistance of a boat designed to Type II is normally expected to be substantially greater than that designed to Type I’.
__________________
If your attitude resembles the south end of a bull heading north, it's time to turn around.
avb3 is offline  
Old 11-12-2014, 16:58   #870
cruiser

Join Date: Jun 2008
Posts: 1,132
Re: The Yard Guys

Quote:
Originally Posted by Cheechako View Post
That's really the heart of it isn't it? two camps......
The one I'm in fully expects to be able to hit a rock with the hull or keel and have little if any damage and also believes a boat that typically wont DOES represent poor construction.
After all... even today's cars are suppose to survive 5 mph without damage as I remember..... water absorbs a lot of energy
Again, all boats we've been discussing take these things into account. From there much of it depends on speed and force of the collision. Did you look through the report Neil linked to? Your assumptions could very well be a little off.

Regardless, the danger is in assuming that no damage occurred...even if you don't see it.
__________________

__________________
smackdaddy is offline  
Closed Thread

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hey, Diesel Guys ! ssullivan General Sailing Forum 20 26-08-2010 06:38
Do you guys really have insurance??? starfish62 Liveaboard's Forum 48 05-07-2007 08:17
OK Florida guys and gals, Who and where is this yard? MNDWGZ Multihull Sailboats 12 20-12-2006 09:25



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 15:43.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.