Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 08-11-2015, 06:54   #166
Registered User

Join Date: Mar 2011
Location: Caribbean
Boat: Oyster 66
Posts: 1,366
Re: Most boats have liners; which ones do it best?

Quote:
Originally Posted by poiu View Post
I think you are wrong in your assumption. A new Jeanneau is the same price as a used Oyster. I did the comparison when I bought mine.
Sorry Abgreenbank. I need to correct my post, I didn't read your post closely. A new Oyster is indeed more expensive than a new Jeanneau.
poiu is offline   Reply With Quote
Old 08-11-2015, 08:33   #167
Registered User

Join Date: Mar 2014
Posts: 81
Re: Most boats have liners; which ones do it best?

Not wanting engage in a slanging match, a quick search reveals this, I was however referring to structural failures and my comment about keels was tongue in cheek.
Maybe failures were due to collision/grounding, but these issues should be addressed in design but I am not suggesting totally mitigated.

One area of failure that seems to be rarely discussed is fatigue failure. My earlier career was flying fighter aircraft, lots of G and consequently fatigue, and just about every type I flew had fatigue issues, and had planned midlife updates to strengthen or replace structural components. Fatigue monitoring was carefully followed and each aircraft had a finite fatigue life and if too much G was pulled fairly major inspection could be required, some individual aircraft even had restrictions on max G to preserve life. All this in pre digital FBW day, modern systems can limit G and incidence.

My point being sailing a yacht hard into a big sea is intimately more stressful than a nice broad reach with a gentle breeze, I guess this seasons transatlantic races have proved that.
In Lanzarote I saw many mini transats with rudder or mast damage after a gentle run down the North African Coast


http://www.oysteryachts.com/breaking...-July-24-2015/

Regards
Ab


Sent from my iPad using Cruisers Sailing Forum
Abgreenbank is offline   Reply With Quote
Old 08-11-2015, 09:19   #168
Registered User

Join Date: Aug 2009
Location: between the devil and the deep blue sea
Boat: a sailing boat
Posts: 20,971
Re: Most boats have liners; which ones do it best?

Quote:
Originally Posted by Abgreenbank View Post

My point being sailing a yacht hard into a big sea is intimately more stressful than a nice broad reach with a gentle breeze, I guess this seasons transatlantic races have proved that.

In Lanzarote I saw many mini transats with rudder or mast damage after a gentle run down the North African Coast
Yes. But sailing a huge downwind SA uldb boat in light conditions can create amazing amt of damage. At times the boat will roll with all its weight while the kite gets a sudden grip on whatever faint breeze there is. At this point the boat gets pulled by the top of its (very fine in Minis) mast with thousands of kilo-meters of force.

Imagine tying the top of the mast to a bollard then waiting for a tug to pass. Can you sense the damage coming?

So I think my point is to a racing boat both heavy going and light conditions can be actually similarly destructive.

b.
barnakiel is offline   Reply With Quote
Old 08-11-2015, 09:25   #169
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 35,024
Re: Most boats have liners; which ones do it best?

Quote:
Originally Posted by Sandero View Post
Your statement about cross section of steel (beams) is not entirely accurate not telling the whole story. Beam action is increased by moving the "mass" of steel... for tension and compression away from the neutral axis but a strong web is required to connect the two making them act as a composite. I believe axial strength for non slender columns is driven by cross section area. Buckling is very much related to the end condition of a column.

. . . .
What you write is entirely correct, but I think that what I wrote was quite enough for purposes of this discussion, and an accurate explanation of the fundamental principle for why cored construction is stronger than solid. It's geometry -- you separate the parts of the structure which are working in compression from those which are working in tension and gain leverage to resist the load. It's a matter of the geometrical translation of the load to be resisted to the compression and tension loads on the structure.

Beam theory formulae for the strength of cored structures does of course assume that the bond between the core and the skins is as strong as the material, and that the core has enough shear and compression strength to resist failure from those modes prior to failure of the skins. If the core is so weak as to allow buckling before the skins reach their failure points, then the formulae don't work.

And the bond is extremely important -- if it fails, the whole structure fails. Which is why until recently balsa works better than foam -- it is much easier to strongly bond to the skins. Newer foams are better and epoxy resin makes as stronger bond, so foam cored structures are getting closer to balsa in strength.


Someone in another post mentioned fatigue failure -- here is yet another advantage of cored boat hulls. The improvement in stiffness of cored structures is even greater than the improvement in strength, and this results in reduced flexing. Hence less fatigue. I think this is important. We know boats which have come apart due to fatigue of the hull (for example, that guy who circumnavigated North and South America single handed via the NW Passage and the Horn). You don't want the hull flexing in a seaway; this can lead to fatigue failure, failure of bulkhead tabbing, etc. That's why quality solid hulls are extremely massive (Oyster) compared to inexpensive solid hulls (Beneteaus -- "Bendy Toys"). I'm not slagging Beneteaus, which I admire and like, but many of them are not designed structurally for long passages in rough seaways.
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
Dockhead is offline   Reply With Quote
Old 08-11-2015, 09:38   #170
Registered User
 
avb3's Avatar

Cruisers Forum Supporter

Join Date: Jul 2010
Location: Florida/Alberta
Boat: Lippincott 30
Posts: 9,901
Images: 1
Re: Most boats have liners; which ones do it best?

Quote:
Originally Posted by Dockhead View Post
....
Someone in another post mentioned fatigue failure -- here is yet another advantage of cored boat hulls. The improvement in stiffness of cored structures is even greater than the improvement in strength, and this results in reduced flexing. Hence less fatigue. I think this is important. We know boats which have come apart due to fatigue of the hull (for example, that guy who circumnavigated North and South America single handed via the NW Passage and the Horn). You don't want the hull flexing in a seaway; this can lead to fatigue failure, failure of bulkhead tabbing, etc. That's why quality solid hulls are extremely massive (Oyster) compared to inexpensive solid hulls (Beneteaus -- "Bendy Toys"). I'm not slagging Beneteaus, which I admire and like, but many of them are not designed structurally for long passages in rough seaways.
You're referring to Matt Rutherford I believe.

http://www.solotheamericas.org

I followed his journey picking him up when he had entered the Bering Sea, and followed around until he got back home. I don't recall any mention of any fatigue damage to his Albin Vega. In fact, he subsequently sold that boat, and as far as I'm aware, it is still happily sailing along.

In my opinion, his journey ranks right up there with Slocum.

Sent from my SM-T230NU using Cruisers Sailing Forum mobile app
__________________
If your attitude resembles the south end of a bull heading north, it's time to turn around.
avb3 is offline   Reply With Quote
Old 08-11-2015, 09:50   #171
Moderator Emeritus
 
Paul Elliott's Avatar

Cruisers Forum Supporter

Join Date: Sep 2006
Posts: 4,663
Images: 4
Re: Most boats have liners; which ones do it best?

Quote:
Originally Posted by barnakiel View Post
[...] So I think my point is to a racing boat both heavy going and light conditions can be actually similarly destructive.
Yes. The worst carnage in the Pacific Cup races I've participated in has taken place during light airs and sloppy seas (we've not seen extremely heavy conditions, but plenty of brisk ones). But this has been failures of rigging -- shrouds, booms, goosenecks, masts, etc. We've seen more than a few rudder failures in moderate to brisk conditions, or whale-strikes.

(To clarify, most of this damage was to other boats, not mine. On VALIS we've had the occasional lightweight block explode in slatting conditions, or gooseneck bolt start to work loose -- nothing catastrophic.)


But isn't this discussion about hull failures, liners, and (now) cored hulls? In most cases the sailing conditions aren't really an issue here.
__________________
Paul Elliott, S/V VALIS - Pacific Seacraft 44 #16 - Friday Harbor, WA
www.sailvalis.com
Paul Elliott is offline   Reply With Quote
Old 08-11-2015, 10:02   #172
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 35,024
Re: Most boats have liners; which ones do it best?

Quote:
Originally Posted by avb3 View Post
You're referring to Matt Rutherford I believe.

Solo Around the America's Under Sail | An audacious attempt at sailing the Northwest Passage and circumnavigating entirety of both continents, to benefit Chesapeake Region Accessible Boating

I followed his journey picking him up when he had entered the Bering Sea, and followed around until he got back home. I don't recall any mention of any fatigue damage to his Albin Vega. In fact, he subsequently sold that boat, and as far as I'm aware, it is still happily sailing along.

In my opinion, his journey ranks right up there with Slocum.
That's the guy! What an amazing voyage!

As far as I can recall, he had a lot of trouble with the hull -- bulkhead broken loose, mast pushing through the deck, things like that.
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
Dockhead is offline   Reply With Quote
Old 08-11-2015, 12:03   #173
Registered User
 
avb3's Avatar

Cruisers Forum Supporter

Join Date: Jul 2010
Location: Florida/Alberta
Boat: Lippincott 30
Posts: 9,901
Images: 1
Re: Most boats have liners; which ones do it best?

Quote:
Originally Posted by Dockhead View Post
That's the guy! What an amazing voyage!

As far as I can recall, he had a lot of trouble with the hull -- bulkhead broken loose, mast pushing through the deck, things like that.
Come to think of it, I now do recall he had an issue with the bulkhead under the mast that kept shifting and groaning. The mast I think he repaired and bolstered before the journey... can't recall now.

Regardless, your right, what a voyage and adventure. And goes to show what a tough little boat a 40 year old Albin Vega is. I'm pretty sure they had no liners.
__________________
If your attitude resembles the south end of a bull heading north, it's time to turn around.
avb3 is offline   Reply With Quote
Old 08-11-2015, 15:25   #174
Registered User

Join Date: Oct 2015
Location: Newfoundland
Boat: Beneteau
Posts: 671
Re: Most boats have liners; which ones do it best?

Got me a 20 year old Beneteau and love it. Liner or no liner what I hear is that many people want total assurance on the ocean and that doesn't exist. Many boats sink but because the ones that are out there in the greatest numbers are statistically most likely to report more issues...Toyota to Rolls. It doesn't mean the Rolls is more reliable or better. More posh is obvious but looking simply at numbers is a fool's game. I recall a very expensive and relatively new Swan coming apart in a mere 3 or 4 metre seas within the last year.
A friend just ran his production boat with liner aground at 5.5 knots and then steamed it 4 hours to my lift without as much as a drop of water coming in. 32 years old and beautifully tough.
nortonscove is offline   Reply With Quote
Old 09-11-2015, 06:39   #175
Registered User

Join Date: Apr 2006
Posts: 4,413
Re: Most boats have liners; which ones do it best?

Core hulls will resist "oil canning" which will cause shear stress in the material and ultimate failure perhaps from excessive flexing. A good way to make a hull stiffer without making it heavier is making it thick. To to this the composite should have a light weight core well bonded to the interior and exterior membranes making them composite. Being composite with the membranes is key to stiffness. I suppose it's possible to use even honey comb cores if they can be properly bonded to the two membranes.

There are other possible benefits in "insulation" when the core has a high r factor than the membranes. This acts somewhat as a thermal break.
Sandero is offline   Reply With Quote
Old 09-11-2015, 06:47   #176
Registered User
 
Muckle Flugga's Avatar

Join Date: Apr 2008
Location: Aboard the Ocean wave
Boat: 55' sloop.
Posts: 1,426
Re: Most boats have liners; which ones do it best?

Quote:
Originally Posted by avb3 View Post
Come to think of it, I now do recall he had an issue with the bulkhead under the mast that kept shifting and groaning. The mast I think he repaired and bolstered before the journey... can't recall now.

Regardless, your right, what a voyage and adventure. And goes to show what a tough little boat a 40 year old Albin Vega is. I'm pretty sure they had no liners.
Having owned and sailed an Albin Vega in higher latitudes for more than a decade (some misty time ago now) and many thousands of miles I can attest that a classic weakness with them was an insufficiently strong deck at the mast step. The original bulkhead did not adequately compensate for the compression loads. My example had a solid triple beam fix for this problem and was no issue at all. It was a necessary addition to any Vega, and likely had not een done in this case. As to being tough? They are fabulous, dry, safe, easy to handle little pocket cruisers and I weathered many a storm and some furious seas in my wee gem.
__________________
‘Structural engineering is the art of modeling materials we do not wholly understand into shapes we cannot precisely analyse as to withstand forces we cannot properly assess in such a way that the public at large has no reason to suspect the extent of our ignorance.’
Muckle Flugga is offline   Reply With Quote
Old 09-11-2015, 06:56   #177
Registered User
 
Muckle Flugga's Avatar

Join Date: Apr 2008
Location: Aboard the Ocean wave
Boat: 55' sloop.
Posts: 1,426
Re: Most boats have liners; which ones do it best?

Quote:
Originally Posted by Sandero View Post
Core hulls will resist "oil canning" which will cause shear stress in the material and ultimate failure perhaps from excessive flexing. A good way to make a hull stiffer without making it heavier is making it thick. To to this the composite should have a light weight core well bonded to the interior and exterior membranes making them composite. Being composite with the membranes is key to stiffness. I suppose it's possible to use even honey comb cores if they can be properly bonded to the two membranes.

There are other possible benefits in "insulation" when the core has a high r factor than the membranes. This acts somewhat as a thermal break.
Here's a picture of me in the bows of a cored hull vessel I found in Dominica a few years back.
Attached Thumbnails
Click image for larger version

Name:	Dominica cored hull.jpg
Views:	133
Size:	77.9 KB
ID:	112602  
__________________
‘Structural engineering is the art of modeling materials we do not wholly understand into shapes we cannot precisely analyse as to withstand forces we cannot properly assess in such a way that the public at large has no reason to suspect the extent of our ignorance.’
Muckle Flugga is offline   Reply With Quote
Old 09-11-2015, 07:03   #178
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Denmark (Winter), Cruising North Sea and Baltic (Summer)
Boat: Cutter-Rigged Moody 54
Posts: 35,024
Re: Most boats have liners; which ones do it best?

Quote:
Originally Posted by Muckle Flugga View Post
Here's a picture of me in the bows of a cored hull vessel I found in Dominica a few years back.
Looks like a Bene! Bet it's not cored below the waterline.

Sent from my D6633 using Cruisers Sailing Forum mobile app
__________________
"You sea! I resign myself to you also . . . . I guess what you mean,
I behold from the beach your crooked inviting fingers,
I believe you refuse to go back without feeling of me;
We must have a turn together . . . . I undress . . . . hurry me out of sight of the land,
Cushion me soft . . . . rock me in billowy drowse,
Dash me with amorous wet . . . . I can repay you."
Walt Whitman
Dockhead is offline   Reply With Quote
Old 09-11-2015, 07:12   #179
Moderator
 
neilpride's Avatar

Join Date: Jul 2009
Location: Sxm , Spain
Boat: CSY 44 Tall rig Sold!
Posts: 4,367
Re: Most boats have liners; which ones do it best?

Quote:
Originally Posted by Muckle Flugga View Post
Here's a picture of me in the bows of a cored hull vessel I found in Dominica a few years back.
Hunter??
neilpride is offline   Reply With Quote
Old 09-11-2015, 07:20   #180
Registered User
 
Muckle Flugga's Avatar

Join Date: Apr 2008
Location: Aboard the Ocean wave
Boat: 55' sloop.
Posts: 1,426
Re: Most boats have liners; which ones do it best?

Quote:
Originally Posted by neilpride View Post
Hunter??
In the words of the immortal Hong Kong Fooey: "Could be!"
__________________
‘Structural engineering is the art of modeling materials we do not wholly understand into shapes we cannot precisely analyse as to withstand forces we cannot properly assess in such a way that the public at large has no reason to suspect the extent of our ignorance.’
Muckle Flugga is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
What Do You Miss the Most? What Do You Like the Most? sww914 Liveaboard's Forum 41 08-12-2023 12:31
What Boats Have the Most Headroom? adell50 Monohull Sailboats 23 11-02-2015 12:01
What was the most important or most interesting ... Rakuflames General Sailing Forum 25 24-09-2012 20:52
Eliminating Boats with Liners - Advice avb3 Monohull Sailboats 57 11-02-2012 13:55
Windvanes: Which Ones and Where !? bdurham Auxiliary Equipment & Dinghy 8 25-04-2011 07:21

Advertise Here


All times are GMT -7. The time now is 10:12.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.